layui_back/back/assets/EZUIKit/js/talk/adapeter.js

(function (f) {
    if (typeof exports === "object" && typeof module !== "undefined") {
        module.exports = f()
    } else if (typeof define === "function" && define.amd) {
        define([], f)
    } else {
        var g;
        if (typeof window !== "undefined") {
            g = window
        } else if (typeof global !== "undefined") {
            g = global
        } else if (typeof self !== "undefined") {
            g = self
        } else {
            g = this
        }
        g.adapter = f()
    }
})(function () {
    var define, module, exports;
    return (function () {
        function r(e, n, t) {
            function o(i, f) {
                if (!n[i]) {
                    if (!e[i]) {
                        var c = "function" == typeof require && require;
                        if (!f && c) return c(i, !0);
                        if (u) return u(i, !0);
                        var a = new Error("Cannot find module '" + i + "'");
                        throw a.code = "MODULE_NOT_FOUND", a
                    }
                    var p = n[i] = {exports: {}};
                    e[i][0].call(p.exports, function (r) {
                        var n = e[i][1][r];
                        return o(n || r)
                    }, p, p.exports, r, e, n, t)
                }
                return n[i].exports
            }

            for (var u = "function" == typeof require && require, i = 0; i < t.length; i++) o(t[i]);
            return o
        }

        return r
    })()({
        1: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */

            'use strict';

            var _adapter_factory = require('./adapter_factory.js');

            var adapter = (0, _adapter_factory.adapterFactory)({window: window});
            module.exports = adapter; // this is the difference from adapter_core.

        }, {"./adapter_factory.js": 2}], 2: [function (require, module, exports) {
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.adapterFactory = adapterFactory;

            var _utils = require('./utils');

            var utils = _interopRequireWildcard(_utils);

            var _chrome_shim = require('./chrome/chrome_shim');

            var chromeShim = _interopRequireWildcard(_chrome_shim);

            var _edge_shim = require('./edge/edge_shim');

            var edgeShim = _interopRequireWildcard(_edge_shim);

            var _firefox_shim = require('./firefox/firefox_shim');

            var firefoxShim = _interopRequireWildcard(_firefox_shim);

            var _safari_shim = require('./safari/safari_shim');

            var safariShim = _interopRequireWildcard(_safari_shim);

            var _common_shim = require('./common_shim');

            var commonShim = _interopRequireWildcard(_common_shim);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            // Shimming starts here.
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            function adapterFactory() {
                var _ref = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {},
                    window = _ref.window;

                var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {
                    shimChrome: true,
                    shimFirefox: true,
                    shimEdge: true,
                    shimSafari: true
                };

                // Utils.
                var logging = utils.log;
                var browserDetails = utils.detectBrowser(window);

                var adapter = {
                    browserDetails: browserDetails,
                    commonShim: commonShim,
                    extractVersion: utils.extractVersion,
                    disableLog: utils.disableLog,
                    disableWarnings: utils.disableWarnings
                };

                // Shim browser if found.
                switch (browserDetails.browser) {
                    case 'chrome':
                        if (!chromeShim || !chromeShim.shimPeerConnection || !options.shimChrome) {
                            logging('Chrome shim is not included in this adapter release.');
                            return adapter;
                        }
                        logging('adapter.js shimming chrome.');
                        // Export to the adapter global object visible in the browser.
                        adapter.browserShim = chromeShim;

                        chromeShim.shimGetUserMedia(window);
                        chromeShim.shimMediaStream(window);
                        chromeShim.shimPeerConnection(window);
                        chromeShim.shimOnTrack(window);
                        chromeShim.shimAddTrackRemoveTrack(window);
                        chromeShim.shimGetSendersWithDtmf(window);
                        chromeShim.shimGetStats(window);
                        chromeShim.shimSenderReceiverGetStats(window);
                        chromeShim.fixNegotiationNeeded(window);

                        commonShim.shimRTCIceCandidate(window);
                        commonShim.shimConnectionState(window);
                        commonShim.shimMaxMessageSize(window);
                        commonShim.shimSendThrowTypeError(window);
                        commonShim.removeAllowExtmapMixed(window);
                        break;
                    case 'firefox':
                        if (!firefoxShim || !firefoxShim.shimPeerConnection || !options.shimFirefox) {
                            logging('Firefox shim is not included in this adapter release.');
                            return adapter;
                        }
                        logging('adapter.js shimming firefox.');
                        // Export to the adapter global object visible in the browser.
                        adapter.browserShim = firefoxShim;

                        firefoxShim.shimGetUserMedia(window);
                        firefoxShim.shimPeerConnection(window);
                        firefoxShim.shimOnTrack(window);
                        firefoxShim.shimRemoveStream(window);
                        firefoxShim.shimSenderGetStats(window);
                        firefoxShim.shimReceiverGetStats(window);
                        firefoxShim.shimRTCDataChannel(window);
                        firefoxShim.shimAddTransceiver(window);
                        firefoxShim.shimCreateOffer(window);
                        firefoxShim.shimCreateAnswer(window);

                        commonShim.shimRTCIceCandidate(window);
                        commonShim.shimConnectionState(window);
                        commonShim.shimMaxMessageSize(window);
                        commonShim.shimSendThrowTypeError(window);
                        break;
                    case 'edge':
                        if (!edgeShim || !edgeShim.shimPeerConnection || !options.shimEdge) {
                            logging('MS edge shim is not included in this adapter release.');
                            return adapter;
                        }
                        logging('adapter.js shimming edge.');
                        // Export to the adapter global object visible in the browser.
                        adapter.browserShim = edgeShim;

                        edgeShim.shimGetUserMedia(window);
                        edgeShim.shimGetDisplayMedia(window);
                        edgeShim.shimPeerConnection(window);
                        edgeShim.shimReplaceTrack(window);

                        // the edge shim implements the full RTCIceCandidate object.

                        commonShim.shimMaxMessageSize(window);
                        commonShim.shimSendThrowTypeError(window);
                        break;
                    case 'safari':
                        if (!safariShim || !options.shimSafari) {
                            logging('Safari shim is not included in this adapter release.');
                            return adapter;
                        }
                        logging('adapter.js shimming safari.');
                        // Export to the adapter global object visible in the browser.
                        adapter.browserShim = safariShim;

                        safariShim.shimRTCIceServerUrls(window);
                        safariShim.shimCreateOfferLegacy(window);
                        safariShim.shimCallbacksAPI(window);
                        safariShim.shimLocalStreamsAPI(window);
                        safariShim.shimRemoteStreamsAPI(window);
                        safariShim.shimTrackEventTransceiver(window);
                        safariShim.shimGetUserMedia(window);

                        commonShim.shimRTCIceCandidate(window);
                        commonShim.shimMaxMessageSize(window);
                        commonShim.shimSendThrowTypeError(window);
                        commonShim.removeAllowExtmapMixed(window);
                        break;
                    default:
                        logging('Unsupported browser!');
                        break;
                }

                return adapter;
            }

            // Browser shims.

        }, {
            "./chrome/chrome_shim": 3,
            "./common_shim": 6,
            "./edge/edge_shim": 7,
            "./firefox/firefox_shim": 11,
            "./safari/safari_shim": 14,
            "./utils": 15
        }], 3: [function (require, module, exports) {

            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.shimGetDisplayMedia = exports.shimGetUserMedia = undefined;

            var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
                return typeof obj;
            } : function (obj) {
                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
            };

            var _getusermedia = require('./getusermedia');

            Object.defineProperty(exports, 'shimGetUserMedia', {
                enumerable: true,
                get: function get() {
                    return _getusermedia.shimGetUserMedia;
                }
            });

            var _getdisplaymedia = require('./getdisplaymedia');

            Object.defineProperty(exports, 'shimGetDisplayMedia', {
                enumerable: true,
                get: function get() {
                    return _getdisplaymedia.shimGetDisplayMedia;
                }
            });
            exports.shimMediaStream = shimMediaStream;
            exports.shimOnTrack = shimOnTrack;
            exports.shimGetSendersWithDtmf = shimGetSendersWithDtmf;
            exports.shimGetStats = shimGetStats;
            exports.shimSenderReceiverGetStats = shimSenderReceiverGetStats;
            exports.shimAddTrackRemoveTrackWithNative = shimAddTrackRemoveTrackWithNative;
            exports.shimAddTrackRemoveTrack = shimAddTrackRemoveTrack;
            exports.shimPeerConnection = shimPeerConnection;
            exports.fixNegotiationNeeded = fixNegotiationNeeded;

            var _utils = require('../utils.js');

            var utils = _interopRequireWildcard(_utils);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            function _defineProperty(obj, key, value) {
                if (key in obj) {
                    Object.defineProperty(obj, key, {
                        value: value,
                        enumerable: true,
                        configurable: true,
                        writable: true
                    });
                } else {
                    obj[key] = value;
                }
                return obj;
            }

            function shimMediaStream(window) {
                window.MediaStream = window.MediaStream || window.webkitMediaStream;
            }

            function shimOnTrack(window) {
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection && !('ontrack' in window.RTCPeerConnection.prototype)) {
                    Object.defineProperty(window.RTCPeerConnection.prototype, 'ontrack', {
                        get: function get() {
                            return this._ontrack;
                        },
                        set: function set(f) {
                            if (this._ontrack) {
                                this.removeEventListener('track', this._ontrack);
                            }
                            this.addEventListener('track', this._ontrack = f);
                        },

                        enumerable: true,
                        configurable: true
                    });
                    var origSetRemoteDescription = window.RTCPeerConnection.prototype.setRemoteDescription;
                    window.RTCPeerConnection.prototype.setRemoteDescription = function setRemoteDescription() {
                        var _this = this;

                        if (!this._ontrackpoly) {
                            this._ontrackpoly = function (e) {
                                // onaddstream does not fire when a track is added to an existing
                                // stream. But stream.onaddtrack is implemented so we use that.
                                e.stream.addEventListener('addtrack', function (te) {
                                    var receiver = void 0;
                                    if (window.RTCPeerConnection.prototype.getReceivers) {
                                        receiver = _this.getReceivers().find(function (r) {
                                            return r.track && r.track.id === te.track.id;
                                        });
                                    } else {
                                        receiver = {track: te.track};
                                    }

                                    var event = new Event('track');
                                    event.track = te.track;
                                    event.receiver = receiver;
                                    event.transceiver = {receiver: receiver};
                                    event.streams = [e.stream];
                                    _this.dispatchEvent(event);
                                });
                                e.stream.getTracks().forEach(function (track) {
                                    var receiver = void 0;
                                    if (window.RTCPeerConnection.prototype.getReceivers) {
                                        receiver = _this.getReceivers().find(function (r) {
                                            return r.track && r.track.id === track.id;
                                        });
                                    } else {
                                        receiver = {track: track};
                                    }
                                    var event = new Event('track');
                                    event.track = track;
                                    event.receiver = receiver;
                                    event.transceiver = {receiver: receiver};
                                    event.streams = [e.stream];
                                    _this.dispatchEvent(event);
                                });
                            };
                            this.addEventListener('addstream', this._ontrackpoly);
                        }
                        return origSetRemoteDescription.apply(this, arguments);
                    };
                } else {
                    // even if RTCRtpTransceiver is in window, it is only used and
                    // emitted in unified-plan. Unfortunately this means we need
                    // to unconditionally wrap the event.
                    utils.wrapPeerConnectionEvent(window, 'track', function (e) {
                        if (!e.transceiver) {
                            Object.defineProperty(e, 'transceiver', {value: {receiver: e.receiver}});
                        }
                        return e;
                    });
                }
            }

            function shimGetSendersWithDtmf(window) {
                // Overrides addTrack/removeTrack, depends on shimAddTrackRemoveTrack.
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection && !('getSenders' in window.RTCPeerConnection.prototype) && 'createDTMFSender' in window.RTCPeerConnection.prototype) {
                    var shimSenderWithDtmf = function shimSenderWithDtmf(pc, track) {
                        return {
                            track: track,
                            get dtmf() {
                                if (this._dtmf === undefined) {
                                    if (track.kind === 'audio') {
                                        this._dtmf = pc.createDTMFSender(track);
                                    } else {
                                        this._dtmf = null;
                                    }
                                }
                                return this._dtmf;
                            },
                            _pc: pc
                        };
                    };

                    // augment addTrack when getSenders is not available.
                    if (!window.RTCPeerConnection.prototype.getSenders) {
                        window.RTCPeerConnection.prototype.getSenders = function getSenders() {
                            this._senders = this._senders || [];
                            return this._senders.slice(); // return a copy of the internal state.
                        };
                        var origAddTrack = window.RTCPeerConnection.prototype.addTrack;
                        window.RTCPeerConnection.prototype.addTrack = function addTrack(track, stream) {
                            var sender = origAddTrack.apply(this, arguments);
                            if (!sender) {
                                sender = shimSenderWithDtmf(this, track);
                                this._senders.push(sender);
                            }
                            return sender;
                        };

                        var origRemoveTrack = window.RTCPeerConnection.prototype.removeTrack;
                        window.RTCPeerConnection.prototype.removeTrack = function removeTrack(sender) {
                            origRemoveTrack.apply(this, arguments);
                            var idx = this._senders.indexOf(sender);
                            if (idx !== -1) {
                                this._senders.splice(idx, 1);
                            }
                        };
                    }
                    var origAddStream = window.RTCPeerConnection.prototype.addStream;
                    window.RTCPeerConnection.prototype.addStream = function addStream(stream) {
                        var _this2 = this;

                        this._senders = this._senders || [];
                        origAddStream.apply(this, [stream]);
                        stream.getTracks().forEach(function (track) {
                            _this2._senders.push(shimSenderWithDtmf(_this2, track));
                        });
                    };

                    var origRemoveStream = window.RTCPeerConnection.prototype.removeStream;
                    window.RTCPeerConnection.prototype.removeStream = function removeStream(stream) {
                        var _this3 = this;

                        this._senders = this._senders || [];
                        origRemoveStream.apply(this, [stream]);

                        stream.getTracks().forEach(function (track) {
                            var sender = _this3._senders.find(function (s) {
                                return s.track === track;
                            });
                            if (sender) {
                                // remove sender
                                _this3._senders.splice(_this3._senders.indexOf(sender), 1);
                            }
                        });
                    };
                } else if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection && 'getSenders' in window.RTCPeerConnection.prototype && 'createDTMFSender' in window.RTCPeerConnection.prototype && window.RTCRtpSender && !('dtmf' in window.RTCRtpSender.prototype)) {
                    var origGetSenders = window.RTCPeerConnection.prototype.getSenders;
                    window.RTCPeerConnection.prototype.getSenders = function getSenders() {
                        var _this4 = this;

                        var senders = origGetSenders.apply(this, []);
                        senders.forEach(function (sender) {
                            return sender._pc = _this4;
                        });
                        return senders;
                    };

                    Object.defineProperty(window.RTCRtpSender.prototype, 'dtmf', {
                        get: function get() {
                            if (this._dtmf === undefined) {
                                if (this.track.kind === 'audio') {
                                    this._dtmf = this._pc.createDTMFSender(this.track);
                                } else {
                                    this._dtmf = null;
                                }
                            }
                            return this._dtmf;
                        }
                    });
                }
            }

            function shimGetStats(window) {
                if (!window.RTCPeerConnection) {
                    return;
                }

                var origGetStats = window.RTCPeerConnection.prototype.getStats;
                window.RTCPeerConnection.prototype.getStats = function getStats() {
                    var _this5 = this;

                    var _arguments = Array.prototype.slice.call(arguments),
                        selector = _arguments[0],
                        onSucc = _arguments[1],
                        onErr = _arguments[2];

                    // If selector is a function then we are in the old style stats so just
                    // pass back the original getStats format to avoid breaking old users.


                    if (arguments.length > 0 && typeof selector === 'function') {
                        return origGetStats.apply(this, arguments);
                    }

                    // When spec-style getStats is supported, return those when called with
                    // either no arguments or the selector argument is null.
                    if (origGetStats.length === 0 && (arguments.length === 0 || typeof selector !== 'function')) {
                        return origGetStats.apply(this, []);
                    }

                    var fixChromeStats_ = function fixChromeStats_(response) {
                        var standardReport = {};
                        var reports = response.result();
                        reports.forEach(function (report) {
                            var standardStats = {
                                id: report.id,
                                timestamp: report.timestamp,
                                type: {
                                    localcandidate: 'local-candidate',
                                    remotecandidate: 'remote-candidate'
                                }[report.type] || report.type
                            };
                            report.names().forEach(function (name) {
                                standardStats[name] = report.stat(name);
                            });
                            standardReport[standardStats.id] = standardStats;
                        });

                        return standardReport;
                    };

                    // shim getStats with maplike support
                    var makeMapStats = function makeMapStats(stats) {
                        return new Map(Object.keys(stats).map(function (key) {
                            return [key, stats[key]];
                        }));
                    };

                    if (arguments.length >= 2) {
                        var successCallbackWrapper_ = function successCallbackWrapper_(response) {
                            onSucc(makeMapStats(fixChromeStats_(response)));
                        };

                        return origGetStats.apply(this, [successCallbackWrapper_, selector]);
                    }

                    // promise-support
                    return new Promise(function (resolve, reject) {
                        origGetStats.apply(_this5, [function (response) {
                            resolve(makeMapStats(fixChromeStats_(response)));
                        }, reject]);
                    }).then(onSucc, onErr);
                };
            }

            function shimSenderReceiverGetStats(window) {
                if (!((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection && window.RTCRtpSender && window.RTCRtpReceiver)) {
                    return;
                }

                // shim sender stats.
                if (!('getStats' in window.RTCRtpSender.prototype)) {
                    var origGetSenders = window.RTCPeerConnection.prototype.getSenders;
                    if (origGetSenders) {
                        window.RTCPeerConnection.prototype.getSenders = function getSenders() {
                            var _this6 = this;

                            var senders = origGetSenders.apply(this, []);
                            senders.forEach(function (sender) {
                                return sender._pc = _this6;
                            });
                            return senders;
                        };
                    }

                    var origAddTrack = window.RTCPeerConnection.prototype.addTrack;
                    if (origAddTrack) {
                        window.RTCPeerConnection.prototype.addTrack = function addTrack() {
                            var sender = origAddTrack.apply(this, arguments);
                            sender._pc = this;
                            return sender;
                        };
                    }
                    window.RTCRtpSender.prototype.getStats = function getStats() {
                        var sender = this;
                        return this._pc.getStats().then(function (result) {
                            return (
                                /* Note: this will include stats of all senders that
             *   send a track with the same id as sender.track as
             *   it is not possible to identify the RTCRtpSender.
             */
                                utils.filterStats(result, sender.track, true)
                            );
                        });
                    };
                }

                // shim receiver stats.
                if (!('getStats' in window.RTCRtpReceiver.prototype)) {
                    var origGetReceivers = window.RTCPeerConnection.prototype.getReceivers;
                    if (origGetReceivers) {
                        window.RTCPeerConnection.prototype.getReceivers = function getReceivers() {
                            var _this7 = this;

                            var receivers = origGetReceivers.apply(this, []);
                            receivers.forEach(function (receiver) {
                                return receiver._pc = _this7;
                            });
                            return receivers;
                        };
                    }
                    utils.wrapPeerConnectionEvent(window, 'track', function (e) {
                        e.receiver._pc = e.srcElement;
                        return e;
                    });
                    window.RTCRtpReceiver.prototype.getStats = function getStats() {
                        var receiver = this;
                        return this._pc.getStats().then(function (result) {
                            return utils.filterStats(result, receiver.track, false);
                        });
                    };
                }

                if (!('getStats' in window.RTCRtpSender.prototype && 'getStats' in window.RTCRtpReceiver.prototype)) {
                    return;
                }

                // shim RTCPeerConnection.getStats(track).
                var origGetStats = window.RTCPeerConnection.prototype.getStats;
                window.RTCPeerConnection.prototype.getStats = function getStats() {
                    if (arguments.length > 0 && arguments[0] instanceof window.MediaStreamTrack) {
                        var track = arguments[0];
                        var sender = void 0;
                        var receiver = void 0;
                        var err = void 0;
                        this.getSenders().forEach(function (s) {
                            if (s.track === track) {
                                if (sender) {
                                    err = true;
                                } else {
                                    sender = s;
                                }
                            }
                        });
                        this.getReceivers().forEach(function (r) {
                            if (r.track === track) {
                                if (receiver) {
                                    err = true;
                                } else {
                                    receiver = r;
                                }
                            }
                            return r.track === track;
                        });
                        if (err || sender && receiver) {
                            return Promise.reject(new DOMException('There are more than one sender or receiver for the track.', 'InvalidAccessError'));
                        } else if (sender) {
                            return sender.getStats();
                        } else if (receiver) {
                            return receiver.getStats();
                        }
                        return Promise.reject(new DOMException('There is no sender or receiver for the track.', 'InvalidAccessError'));
                    }
                    return origGetStats.apply(this, arguments);
                };
            }

            function shimAddTrackRemoveTrackWithNative(window) {
                // shim addTrack/removeTrack with native variants in order to make
                // the interactions with legacy getLocalStreams behave as in other browsers.
                // Keeps a mapping stream.id => [stream, rtpsenders...]
                window.RTCPeerConnection.prototype.getLocalStreams = function getLocalStreams() {
                    var _this8 = this;

                    this._shimmedLocalStreams = this._shimmedLocalStreams || {};
                    return Object.keys(this._shimmedLocalStreams).map(function (streamId) {
                        return _this8._shimmedLocalStreams[streamId][0];
                    });
                };

                var origAddTrack = window.RTCPeerConnection.prototype.addTrack;
                window.RTCPeerConnection.prototype.addTrack = function addTrack(track, stream) {
                    if (!stream) {
                        return origAddTrack.apply(this, arguments);
                    }
                    this._shimmedLocalStreams = this._shimmedLocalStreams || {};

                    var sender = origAddTrack.apply(this, arguments);
                    if (!this._shimmedLocalStreams[stream.id]) {
                        this._shimmedLocalStreams[stream.id] = [stream, sender];
                    } else if (this._shimmedLocalStreams[stream.id].indexOf(sender) === -1) {
                        this._shimmedLocalStreams[stream.id].push(sender);
                    }
                    return sender;
                };

                var origAddStream = window.RTCPeerConnection.prototype.addStream;
                window.RTCPeerConnection.prototype.addStream = function addStream(stream) {
                    var _this9 = this;

                    this._shimmedLocalStreams = this._shimmedLocalStreams || {};

                    stream.getTracks().forEach(function (track) {
                        var alreadyExists = _this9.getSenders().find(function (s) {
                            return s.track === track;
                        });
                        if (alreadyExists) {
                            throw new DOMException('Track already exists.', 'InvalidAccessError');
                        }
                    });
                    var existingSenders = this.getSenders();
                    origAddStream.apply(this, arguments);
                    var newSenders = this.getSenders().filter(function (newSender) {
                        return existingSenders.indexOf(newSender) === -1;
                    });
                    this._shimmedLocalStreams[stream.id] = [stream].concat(newSenders);
                };

                var origRemoveStream = window.RTCPeerConnection.prototype.removeStream;
                window.RTCPeerConnection.prototype.removeStream = function removeStream(stream) {
                    this._shimmedLocalStreams = this._shimmedLocalStreams || {};
                    delete this._shimmedLocalStreams[stream.id];
                    return origRemoveStream.apply(this, arguments);
                };

                var origRemoveTrack = window.RTCPeerConnection.prototype.removeTrack;
                window.RTCPeerConnection.prototype.removeTrack = function removeTrack(sender) {
                    var _this10 = this;

                    this._shimmedLocalStreams = this._shimmedLocalStreams || {};
                    if (sender) {
                        Object.keys(this._shimmedLocalStreams).forEach(function (streamId) {
                            var idx = _this10._shimmedLocalStreams[streamId].indexOf(sender);
                            if (idx !== -1) {
                                _this10._shimmedLocalStreams[streamId].splice(idx, 1);
                            }
                            if (_this10._shimmedLocalStreams[streamId].length === 1) {
                                delete _this10._shimmedLocalStreams[streamId];
                            }
                        });
                    }
                    return origRemoveTrack.apply(this, arguments);
                };
            }

            function shimAddTrackRemoveTrack(window) {
                if (!window.RTCPeerConnection) {
                    return;
                }
                var browserDetails = utils.detectBrowser(window);
                // shim addTrack and removeTrack.
                if (window.RTCPeerConnection.prototype.addTrack && browserDetails.version >= 65) {
                    return shimAddTrackRemoveTrackWithNative(window);
                }

                // also shim pc.getLocalStreams when addTrack is shimmed
                // to return the original streams.
                var origGetLocalStreams = window.RTCPeerConnection.prototype.getLocalStreams;
                window.RTCPeerConnection.prototype.getLocalStreams = function getLocalStreams() {
                    var _this11 = this;

                    var nativeStreams = origGetLocalStreams.apply(this);
                    this._reverseStreams = this._reverseStreams || {};
                    return nativeStreams.map(function (stream) {
                        return _this11._reverseStreams[stream.id];
                    });
                };

                var origAddStream = window.RTCPeerConnection.prototype.addStream;
                window.RTCPeerConnection.prototype.addStream = function addStream(stream) {
                    var _this12 = this;

                    this._streams = this._streams || {};
                    this._reverseStreams = this._reverseStreams || {};

                    stream.getTracks().forEach(function (track) {
                        var alreadyExists = _this12.getSenders().find(function (s) {
                            return s.track === track;
                        });
                        if (alreadyExists) {
                            throw new DOMException('Track already exists.', 'InvalidAccessError');
                        }
                    });
                    // Add identity mapping for consistency with addTrack.
                    // Unless this is being used with a stream from addTrack.
                    if (!this._reverseStreams[stream.id]) {
                        var newStream = new window.MediaStream(stream.getTracks());
                        this._streams[stream.id] = newStream;
                        this._reverseStreams[newStream.id] = stream;
                        stream = newStream;
                    }
                    origAddStream.apply(this, [stream]);
                };

                var origRemoveStream = window.RTCPeerConnection.prototype.removeStream;
                window.RTCPeerConnection.prototype.removeStream = function removeStream(stream) {
                    this._streams = this._streams || {};
                    this._reverseStreams = this._reverseStreams || {};

                    origRemoveStream.apply(this, [this._streams[stream.id] || stream]);
                    delete this._reverseStreams[this._streams[stream.id] ? this._streams[stream.id].id : stream.id];
                    delete this._streams[stream.id];
                };

                window.RTCPeerConnection.prototype.addTrack = function addTrack(track, stream) {
                    var _this13 = this;

                    if (this.signalingState === 'closed') {
                        throw new DOMException('The RTCPeerConnection\'s signalingState is \'closed\'.', 'InvalidStateError');
                    }
                    var streams = [].slice.call(arguments, 1);
                    if (streams.length !== 1 || !streams[0].getTracks().find(function (t) {
                        return t === track;
                    })) {
                        // this is not fully correct but all we can manage without
                        // [[associated MediaStreams]] internal slot.
                        throw new DOMException('The adapter.js addTrack polyfill only supports a single ' + ' stream which is associated with the specified track.', 'NotSupportedError');
                    }

                    var alreadyExists = this.getSenders().find(function (s) {
                        return s.track === track;
                    });
                    if (alreadyExists) {
                        throw new DOMException('Track already exists.', 'InvalidAccessError');
                    }

                    this._streams = this._streams || {};
                    this._reverseStreams = this._reverseStreams || {};
                    var oldStream = this._streams[stream.id];
                    if (oldStream) {
                        // this is using odd Chrome behaviour, use with caution:
                        // https://bugs.chromium.org/p/webrtc/issues/detail?id=7815
                        // Note: we rely on the high-level addTrack/dtmf shim to
                        // create the sender with a dtmf sender.
                        oldStream.addTrack(track);

                        // Trigger ONN async.
                        Promise.resolve().then(function () {
                            _this13.dispatchEvent(new Event('negotiationneeded'));
                        });
                    } else {
                        var newStream = new window.MediaStream([track]);
                        this._streams[stream.id] = newStream;
                        this._reverseStreams[newStream.id] = stream;
                        this.addStream(newStream);
                    }
                    return this.getSenders().find(function (s) {
                        return s.track === track;
                    });
                };

                // replace the internal stream id with the external one and
                // vice versa.
                function replaceInternalStreamId(pc, description) {
                    var sdp = description.sdp;
                    Object.keys(pc._reverseStreams || []).forEach(function (internalId) {
                        var externalStream = pc._reverseStreams[internalId];
                        var internalStream = pc._streams[externalStream.id];
                        sdp = sdp.replace(new RegExp(internalStream.id, 'g'), externalStream.id);
                    });
                    return new RTCSessionDescription({
                        type: description.type,
                        sdp: sdp
                    });
                }

                function replaceExternalStreamId(pc, description) {
                    var sdp = description.sdp;
                    Object.keys(pc._reverseStreams || []).forEach(function (internalId) {
                        var externalStream = pc._reverseStreams[internalId];
                        var internalStream = pc._streams[externalStream.id];
                        sdp = sdp.replace(new RegExp(externalStream.id, 'g'), internalStream.id);
                    });
                    return new RTCSessionDescription({
                        type: description.type,
                        sdp: sdp
                    });
                }

                ['createOffer', 'createAnswer'].forEach(function (method) {
                    var nativeMethod = window.RTCPeerConnection.prototype[method];
                    var methodObj = _defineProperty({}, method, function () {
                        var _this14 = this;

                        var args = arguments;
                        var isLegacyCall = arguments.length && typeof arguments[0] === 'function';
                        if (isLegacyCall) {
                            return nativeMethod.apply(this, [function (description) {
                                var desc = replaceInternalStreamId(_this14, description);
                                args[0].apply(null, [desc]);
                            }, function (err) {
                                if (args[1]) {
                                    args[1].apply(null, err);
                                }
                            }, arguments[2]]);
                        }
                        return nativeMethod.apply(this, arguments).then(function (description) {
                            return replaceInternalStreamId(_this14, description);
                        });
                    });
                    window.RTCPeerConnection.prototype[method] = methodObj[method];
                });

                var origSetLocalDescription = window.RTCPeerConnection.prototype.setLocalDescription;
                window.RTCPeerConnection.prototype.setLocalDescription = function setLocalDescription() {
                    if (!arguments.length || !arguments[0].type) {
                        return origSetLocalDescription.apply(this, arguments);
                    }
                    arguments[0] = replaceExternalStreamId(this, arguments[0]);
                    return origSetLocalDescription.apply(this, arguments);
                };

                // TODO: mangle getStats: https://w3c.github.io/webrtc-stats/#dom-rtcmediastreamstats-streamidentifier

                var origLocalDescription = Object.getOwnPropertyDescriptor(window.RTCPeerConnection.prototype, 'localDescription');
                Object.defineProperty(window.RTCPeerConnection.prototype, 'localDescription', {
                    get: function get() {
                        var description = origLocalDescription.get.apply(this);
                        if (description.type === '') {
                            return description;
                        }
                        return replaceInternalStreamId(this, description);
                    }
                });

                window.RTCPeerConnection.prototype.removeTrack = function removeTrack(sender) {
                    var _this15 = this;

                    if (this.signalingState === 'closed') {
                        throw new DOMException('The RTCPeerConnection\'s signalingState is \'closed\'.', 'InvalidStateError');
                    }
                    // We can not yet check for sender instanceof RTCRtpSender
                    // since we shim RTPSender. So we check if sender._pc is set.
                    if (!sender._pc) {
                        throw new DOMException('Argument 1 of RTCPeerConnection.removeTrack ' + 'does not implement interface RTCRtpSender.', 'TypeError');
                    }
                    var isLocal = sender._pc === this;
                    if (!isLocal) {
                        throw new DOMException('Sender was not created by this connection.', 'InvalidAccessError');
                    }

                    // Search for the native stream the senders track belongs to.
                    this._streams = this._streams || {};
                    var stream = void 0;
                    Object.keys(this._streams).forEach(function (streamid) {
                        var hasTrack = _this15._streams[streamid].getTracks().find(function (track) {
                            return sender.track === track;
                        });
                        if (hasTrack) {
                            stream = _this15._streams[streamid];
                        }
                    });

                    if (stream) {
                        if (stream.getTracks().length === 1) {
                            // if this is the last track of the stream, remove the stream. This
                            // takes care of any shimmed _senders.
                            this.removeStream(this._reverseStreams[stream.id]);
                        } else {
                            // relying on the same odd chrome behaviour as above.
                            stream.removeTrack(sender.track);
                        }
                        this.dispatchEvent(new Event('negotiationneeded'));
                    }
                };
            }

            function shimPeerConnection(window) {
                var browserDetails = utils.detectBrowser(window);

                if (!window.RTCPeerConnection && window.webkitRTCPeerConnection) {
                    // very basic support for old versions.
                    window.RTCPeerConnection = window.webkitRTCPeerConnection;
                }
                if (!window.RTCPeerConnection) {
                    return;
                }

                // shim implicit creation of RTCSessionDescription/RTCIceCandidate
                if (browserDetails.version < 53) {
                    ['setLocalDescription', 'setRemoteDescription', 'addIceCandidate'].forEach(function (method) {
                        var nativeMethod = window.RTCPeerConnection.prototype[method];
                        var methodObj = _defineProperty({}, method, function () {
                            arguments[0] = new (method === 'addIceCandidate' ? window.RTCIceCandidate : window.RTCSessionDescription)(arguments[0]);
                            return nativeMethod.apply(this, arguments);
                        });
                        window.RTCPeerConnection.prototype[method] = methodObj[method];
                    });
                }

                // support for addIceCandidate(null or undefined)
                var nativeAddIceCandidate = window.RTCPeerConnection.prototype.addIceCandidate;
                window.RTCPeerConnection.prototype.addIceCandidate = function addIceCandidate() {
                    if (!arguments[0]) {
                        if (arguments[1]) {
                            arguments[1].apply(null);
                        }
                        return Promise.resolve();
                    }
                    // Firefox 68+ emits and processes {candidate: "", ...}, ignore
                    // in older versions. Native support planned for Chrome M77.
                    if (browserDetails.version < 78 && arguments[0] && arguments[0].candidate === '') {
                        return Promise.resolve();
                    }
                    return nativeAddIceCandidate.apply(this, arguments);
                };
            }

            function fixNegotiationNeeded(window) {
                utils.wrapPeerConnectionEvent(window, 'negotiationneeded', function (e) {
                    var pc = e.target;
                    if (pc.signalingState !== 'stable') {
                        return;
                    }
                    return e;
                });
            }

        }, {"../utils.js": 15, "./getdisplaymedia": 4, "./getusermedia": 5}], 4: [function (require, module, exports) {
            /*
   *  Copyright (c) 2018 The adapter.js project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.shimGetDisplayMedia = shimGetDisplayMedia;

            function shimGetDisplayMedia(window, getSourceId) {
                if (window.navigator.mediaDevices && 'getDisplayMedia' in window.navigator.mediaDevices) {
                    return;
                }
                if (!window.navigator.mediaDevices) {
                    return;
                }
                // getSourceId is a function that returns a promise resolving with
                // the sourceId of the screen/window/tab to be shared.
                if (typeof getSourceId !== 'function') {
                    console.error('shimGetDisplayMedia: getSourceId argument is not ' + 'a function');
                    return;
                }
                window.navigator.mediaDevices.getDisplayMedia = function getDisplayMedia(constraints) {
                    return getSourceId(constraints).then(function (sourceId) {
                        var widthSpecified = constraints.video && constraints.video.width;
                        var heightSpecified = constraints.video && constraints.video.height;
                        var frameRateSpecified = constraints.video && constraints.video.frameRate;
                        constraints.video = {
                            mandatory: {
                                chromeMediaSource: 'desktop',
                                chromeMediaSourceId: sourceId,
                                maxFrameRate: frameRateSpecified || 3
                            }
                        };
                        if (widthSpecified) {
                            constraints.video.mandatory.maxWidth = widthSpecified;
                        }
                        if (heightSpecified) {
                            constraints.video.mandatory.maxHeight = heightSpecified;
                        }
                        return window.navigator.mediaDevices.getUserMedia(constraints);
                    });
                };
            }

        }, {}], 5: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });

            var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
                return typeof obj;
            } : function (obj) {
                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
            };

            exports.shimGetUserMedia = shimGetUserMedia;

            var _utils = require('../utils.js');

            var utils = _interopRequireWildcard(_utils);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            var logging = utils.log;

            function shimGetUserMedia(window) {
                var navigator = window && window.navigator;

                if (!navigator.mediaDevices) {
                    return;
                }

                var browserDetails = utils.detectBrowser(window);

                var constraintsToChrome_ = function constraintsToChrome_(c) {
                    if ((typeof c === 'undefined' ? 'undefined' : _typeof(c)) !== 'object' || c.mandatory || c.optional) {
                        return c;
                    }
                    var cc = {};
                    Object.keys(c).forEach(function (key) {
                        if (key === 'require' || key === 'advanced' || key === 'mediaSource') {
                            return;
                        }
                        var r = _typeof(c[key]) === 'object' ? c[key] : {ideal: c[key]};
                        if (r.exact !== undefined && typeof r.exact === 'number') {
                            r.min = r.max = r.exact;
                        }
                        var oldname_ = function oldname_(prefix, name) {
                            if (prefix) {
                                return prefix + name.charAt(0).toUpperCase() + name.slice(1);
                            }
                            return name === 'deviceId' ? 'sourceId' : name;
                        };
                        if (r.ideal !== undefined) {
                            cc.optional = cc.optional || [];
                            var oc = {};
                            if (typeof r.ideal === 'number') {
                                oc[oldname_('min', key)] = r.ideal;
                                cc.optional.push(oc);
                                oc = {};
                                oc[oldname_('max', key)] = r.ideal;
                                cc.optional.push(oc);
                            } else {
                                oc[oldname_('', key)] = r.ideal;
                                cc.optional.push(oc);
                            }
                        }
                        if (r.exact !== undefined && typeof r.exact !== 'number') {
                            cc.mandatory = cc.mandatory || {};
                            cc.mandatory[oldname_('', key)] = r.exact;
                        } else {
                            ['min', 'max'].forEach(function (mix) {
                                if (r[mix] !== undefined) {
                                    cc.mandatory = cc.mandatory || {};
                                    cc.mandatory[oldname_(mix, key)] = r[mix];
                                }
                            });
                        }
                    });
                    if (c.advanced) {
                        cc.optional = (cc.optional || []).concat(c.advanced);
                    }
                    return cc;
                };

                var shimConstraints_ = function shimConstraints_(constraints, func) {
                    if (browserDetails.version >= 61) {
                        return func(constraints);
                    }
                    constraints = JSON.parse(JSON.stringify(constraints));
                    if (constraints && _typeof(constraints.audio) === 'object') {
                        var remap = function remap(obj, a, b) {
                            if (a in obj && !(b in obj)) {
                                obj[b] = obj[a];
                                delete obj[a];
                            }
                        };
                        constraints = JSON.parse(JSON.stringify(constraints));
                        remap(constraints.audio, 'autoGainControl', 'googAutoGainControl');
                        remap(constraints.audio, 'noiseSuppression', 'googNoiseSuppression');
                        constraints.audio = constraintsToChrome_(constraints.audio);
                    }
                    if (constraints && _typeof(constraints.video) === 'object') {
                        // Shim facingMode for mobile & surface pro.
                        var face = constraints.video.facingMode;
                        face = face && ((typeof face === 'undefined' ? 'undefined' : _typeof(face)) === 'object' ? face : {ideal: face});
                        var getSupportedFacingModeLies = browserDetails.version < 66;

                        if (face && (face.exact === 'user' || face.exact === 'environment' || face.ideal === 'user' || face.ideal === 'environment') && !(navigator.mediaDevices.getSupportedConstraints && navigator.mediaDevices.getSupportedConstraints().facingMode && !getSupportedFacingModeLies)) {
                            delete constraints.video.facingMode;
                            var matches = void 0;
                            if (face.exact === 'environment' || face.ideal === 'environment') {
                                matches = ['back', 'rear'];
                            } else if (face.exact === 'user' || face.ideal === 'user') {
                                matches = ['front'];
                            }
                            if (matches) {
                                // Look for matches in label, or use last cam for back (typical).
                                return navigator.mediaDevices.enumerateDevices().then(function (devices) {
                                    devices = devices.filter(function (d) {
                                        return d.kind === 'videoinput';
                                    });
                                    var dev = devices.find(function (d) {
                                        return matches.some(function (match) {
                                            return d.label.toLowerCase().includes(match);
                                        });
                                    });
                                    if (!dev && devices.length && matches.includes('back')) {
                                        dev = devices[devices.length - 1]; // more likely the back cam
                                    }
                                    if (dev) {
                                        constraints.video.deviceId = face.exact ? {exact: dev.deviceId} : {ideal: dev.deviceId};
                                    }
                                    constraints.video = constraintsToChrome_(constraints.video);
                                    logging('chrome: ' + JSON.stringify(constraints));
                                    return func(constraints);
                                });
                            }
                        }
                        constraints.video = constraintsToChrome_(constraints.video);
                    }
                    logging('chrome: ' + JSON.stringify(constraints));
                    return func(constraints);
                };

                var shimError_ = function shimError_(e) {
                    if (browserDetails.version >= 64) {
                        return e;
                    }
                    return {
                        name: {
                            PermissionDeniedError: 'NotAllowedError',
                            PermissionDismissedError: 'NotAllowedError',
                            InvalidStateError: 'NotAllowedError',
                            DevicesNotFoundError: 'NotFoundError',
                            ConstraintNotSatisfiedError: 'OverconstrainedError',
                            TrackStartError: 'NotReadableError',
                            MediaDeviceFailedDueToShutdown: 'NotAllowedError',
                            MediaDeviceKillSwitchOn: 'NotAllowedError',
                            TabCaptureError: 'AbortError',
                            ScreenCaptureError: 'AbortError',
                            DeviceCaptureError: 'AbortError'
                        }[e.name] || e.name,
                        message: e.message,
                        constraint: e.constraint || e.constraintName,
                        toString: function toString() {
                            return this.name + (this.message && ': ') + this.message;
                        }
                    };
                };

                var getUserMedia_ = function getUserMedia_(constraints, onSuccess, onError) {
                    shimConstraints_(constraints, function (c) {
                        navigator.webkitGetUserMedia(c, onSuccess, function (e) {
                            if (onError) {
                                onError(shimError_(e));
                            }
                        });
                    });
                };
                navigator.getUserMedia = getUserMedia_.bind(navigator);

                // Even though Chrome 45 has navigator.mediaDevices and a getUserMedia
                // function which returns a Promise, it does not accept spec-style
                // constraints.
                if (navigator.mediaDevices.getUserMedia) {
                    var origGetUserMedia = navigator.mediaDevices.getUserMedia.bind(navigator.mediaDevices);
                    navigator.mediaDevices.getUserMedia = function (cs) {
                        return shimConstraints_(cs, function (c) {
                            return origGetUserMedia(c).then(function (stream) {
                                if (c.audio && !stream.getAudioTracks().length || c.video && !stream.getVideoTracks().length) {
                                    stream.getTracks().forEach(function (track) {
                                        track.stop();
                                    });
                                    throw new DOMException('', 'NotFoundError');
                                }
                                return stream;
                            }, function (e) {
                                return Promise.reject(shimError_(e));
                            });
                        });
                    };
                }
            }

        }, {"../utils.js": 15}], 6: [function (require, module, exports) {
            /*
   *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });

            var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
                return typeof obj;
            } : function (obj) {
                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
            };

            exports.shimRTCIceCandidate = shimRTCIceCandidate;
            exports.shimMaxMessageSize = shimMaxMessageSize;
            exports.shimSendThrowTypeError = shimSendThrowTypeError;
            exports.shimConnectionState = shimConnectionState;
            exports.removeAllowExtmapMixed = removeAllowExtmapMixed;

            var _sdp = require('sdp');

            var _sdp2 = _interopRequireDefault(_sdp);

            var _utils = require('./utils');

            var utils = _interopRequireWildcard(_utils);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            function _interopRequireDefault(obj) {
                return obj && obj.__esModule ? obj : {default: obj};
            }

            function shimRTCIceCandidate(window) {
                // foundation is arbitrarily chosen as an indicator for full support for
                // https://w3c.github.io/webrtc-pc/#rtcicecandidate-interface
                if (!window.RTCIceCandidate || window.RTCIceCandidate && 'foundation' in window.RTCIceCandidate.prototype) {
                    return;
                }

                var NativeRTCIceCandidate = window.RTCIceCandidate;
                window.RTCIceCandidate = function RTCIceCandidate(args) {
                    // Remove the a= which shouldn't be part of the candidate string.
                    if ((typeof args === 'undefined' ? 'undefined' : _typeof(args)) === 'object' && args.candidate && args.candidate.indexOf('a=') === 0) {
                        args = JSON.parse(JSON.stringify(args));
                        args.candidate = args.candidate.substr(2);
                    }

                    if (args.candidate && args.candidate.length) {
                        // Augment the native candidate with the parsed fields.
                        var nativeCandidate = new NativeRTCIceCandidate(args);
                        var parsedCandidate = _sdp2.default.parseCandidate(args.candidate);
                        var augmentedCandidate = Object.assign(nativeCandidate, parsedCandidate);

                        // Add a serializer that does not serialize the extra attributes.
                        augmentedCandidate.toJSON = function toJSON() {
                            return {
                                candidate: augmentedCandidate.candidate,
                                sdpMid: augmentedCandidate.sdpMid,
                                sdpMLineIndex: augmentedCandidate.sdpMLineIndex,
                                usernameFragment: augmentedCandidate.usernameFragment
                            };
                        };
                        return augmentedCandidate;
                    }
                    return new NativeRTCIceCandidate(args);
                };
                window.RTCIceCandidate.prototype = NativeRTCIceCandidate.prototype;

                // Hook up the augmented candidate in onicecandidate and
                // addEventListener('icecandidate', ...)
                utils.wrapPeerConnectionEvent(window, 'icecandidate', function (e) {
                    if (e.candidate) {
                        Object.defineProperty(e, 'candidate', {
                            value: new window.RTCIceCandidate(e.candidate),
                            writable: 'false'
                        });
                    }
                    return e;
                });
            }

            function shimMaxMessageSize(window) {
                if (!window.RTCPeerConnection) {
                    return;
                }
                var browserDetails = utils.detectBrowser(window);

                if (!('sctp' in window.RTCPeerConnection.prototype)) {
                    Object.defineProperty(window.RTCPeerConnection.prototype, 'sctp', {
                        get: function get() {
                            return typeof this._sctp === 'undefined' ? null : this._sctp;
                        }
                    });
                }

                var sctpInDescription = function sctpInDescription(description) {
                    if (!description || !description.sdp) {
                        return false;
                    }
                    var sections = _sdp2.default.splitSections(description.sdp);
                    sections.shift();
                    return sections.some(function (mediaSection) {
                        var mLine = _sdp2.default.parseMLine(mediaSection);
                        return mLine && mLine.kind === 'application' && mLine.protocol.indexOf('SCTP') !== -1;
                    });
                };

                var getRemoteFirefoxVersion = function getRemoteFirefoxVersion(description) {
                    // TODO: Is there a better solution for detecting Firefox?
                    var match = description.sdp.match(/mozilla...THIS_IS_SDPARTA-(\d+)/);
                    if (match === null || match.length < 2) {
                        return -1;
                    }
                    var version = parseInt(match[1], 10);
                    // Test for NaN (yes, this is ugly)
                    return version !== version ? -1 : version;
                };

                var getCanSendMaxMessageSize = function getCanSendMaxMessageSize(remoteIsFirefox) {
                    // Every implementation we know can send at least 64 KiB.
                    // Note: Although Chrome is technically able to send up to 256 KiB, the
                    //       data does not reach the other peer reliably.
                    //       See: https://bugs.chromium.org/p/webrtc/issues/detail?id=8419
                    var canSendMaxMessageSize = 65536;
                    if (browserDetails.browser === 'firefox') {
                        if (browserDetails.version < 57) {
                            if (remoteIsFirefox === -1) {
                                // FF < 57 will send in 16 KiB chunks using the deprecated PPID
                                // fragmentation.
                                canSendMaxMessageSize = 16384;
                            } else {
                                // However, other FF (and RAWRTC) can reassemble PPID-fragmented
                                // messages. Thus, supporting ~2 GiB when sending.
                                canSendMaxMessageSize = 2147483637;
                            }
                        } else if (browserDetails.version < 60) {
                            // Currently, all FF >= 57 will reset the remote maximum message size
                            // to the default value when a data channel is created at a later
                            // stage. :(
                            // See: https://bugzilla.mozilla.org/show_bug.cgi?id=1426831
                            canSendMaxMessageSize = browserDetails.version === 57 ? 65535 : 65536;
                        } else {
                            // FF >= 60 supports sending ~2 GiB
                            canSendMaxMessageSize = 2147483637;
                        }
                    }
                    return canSendMaxMessageSize;
                };

                var getMaxMessageSize = function getMaxMessageSize(description, remoteIsFirefox) {
                    // Note: 65536 bytes is the default value from the SDP spec. Also,
                    //       every implementation we know supports receiving 65536 bytes.
                    var maxMessageSize = 65536;

                    // FF 57 has a slightly incorrect default remote max message size, so
                    // we need to adjust it here to avoid a failure when sending.
                    // See: https://bugzilla.mozilla.org/show_bug.cgi?id=1425697
                    if (browserDetails.browser === 'firefox' && browserDetails.version === 57) {
                        maxMessageSize = 65535;
                    }

                    var match = _sdp2.default.matchPrefix(description.sdp, 'a=max-message-size:');
                    if (match.length > 0) {
                        maxMessageSize = parseInt(match[0].substr(19), 10);
                    } else if (browserDetails.browser === 'firefox' && remoteIsFirefox !== -1) {
                        // If the maximum message size is not present in the remote SDP and
                        // both local and remote are Firefox, the remote peer can receive
                        // ~2 GiB.
                        maxMessageSize = 2147483637;
                    }
                    return maxMessageSize;
                };

                var origSetRemoteDescription = window.RTCPeerConnection.prototype.setRemoteDescription;
                window.RTCPeerConnection.prototype.setRemoteDescription = function setRemoteDescription() {
                    this._sctp = null;
                    // Chrome decided to not expose .sctp in plan-b mode.
                    // As usual, adapter.js has to do an 'ugly worakaround'
                    // to cover up the mess.
                    if (browserDetails.browser === 'chrome' && browserDetails.version >= 76) {
                        var _getConfiguration = this.getConfiguration(),
                            sdpSemantics = _getConfiguration.sdpSemantics;

                        if (sdpSemantics === 'plan-b') {
                            Object.defineProperty(this, 'sctp', {
                                get: function get() {
                                    return typeof this._sctp === 'undefined' ? null : this._sctp;
                                },

                                enumerable: true,
                                configurable: true
                            });
                        }
                    }

                    if (sctpInDescription(arguments[0])) {
                        // Check if the remote is FF.
                        var isFirefox = getRemoteFirefoxVersion(arguments[0]);

                        // Get the maximum message size the local peer is capable of sending
                        var canSendMMS = getCanSendMaxMessageSize(isFirefox);

                        // Get the maximum message size of the remote peer.
                        var remoteMMS = getMaxMessageSize(arguments[0], isFirefox);

                        // Determine final maximum message size
                        var maxMessageSize = void 0;
                        if (canSendMMS === 0 && remoteMMS === 0) {
                            maxMessageSize = Number.POSITIVE_INFINITY;
                        } else if (canSendMMS === 0 || remoteMMS === 0) {
                            maxMessageSize = Math.max(canSendMMS, remoteMMS);
                        } else {
                            maxMessageSize = Math.min(canSendMMS, remoteMMS);
                        }

                        // Create a dummy RTCSctpTransport object and the 'maxMessageSize'
                        // attribute.
                        var sctp = {};
                        Object.defineProperty(sctp, 'maxMessageSize', {
                            get: function get() {
                                return maxMessageSize;
                            }
                        });
                        this._sctp = sctp;
                    }

                    return origSetRemoteDescription.apply(this, arguments);
                };
            }

            function shimSendThrowTypeError(window) {
                if (!(window.RTCPeerConnection && 'createDataChannel' in window.RTCPeerConnection.prototype)) {
                    return;
                }

                // Note: Although Firefox >= 57 has a native implementation, the maximum
                //       message size can be reset for all data channels at a later stage.
                //       See: https://bugzilla.mozilla.org/show_bug.cgi?id=1426831

                function wrapDcSend(dc, pc) {
                    var origDataChannelSend = dc.send;
                    dc.send = function send() {
                        var data = arguments[0];
                        var length = data.length || data.size || data.byteLength;
                        if (dc.readyState === 'open' && pc.sctp && length > pc.sctp.maxMessageSize) {
                            throw new TypeError('Message too large (can send a maximum of ' + pc.sctp.maxMessageSize + ' bytes)');
                        }
                        return origDataChannelSend.apply(dc, arguments);
                    };
                }

                var origCreateDataChannel = window.RTCPeerConnection.prototype.createDataChannel;
                window.RTCPeerConnection.prototype.createDataChannel = function createDataChannel() {
                    var dataChannel = origCreateDataChannel.apply(this, arguments);
                    wrapDcSend(dataChannel, this);
                    return dataChannel;
                };
                utils.wrapPeerConnectionEvent(window, 'datachannel', function (e) {
                    wrapDcSend(e.channel, e.target);
                    return e;
                });
            }

            /* shims RTCConnectionState by pretending it is the same as iceConnectionState.
   * See https://bugs.chromium.org/p/webrtc/issues/detail?id=6145#c12
   * for why this is a valid hack in Chrome. In Firefox it is slightly incorrect
   * since DTLS failures would be hidden. See
   * https://bugzilla.mozilla.org/show_bug.cgi?id=1265827
   * for the Firefox tracking bug.
   */
            function shimConnectionState(window) {
                if (!window.RTCPeerConnection || 'connectionState' in window.RTCPeerConnection.prototype) {
                    return;
                }
                var proto = window.RTCPeerConnection.prototype;
                Object.defineProperty(proto, 'connectionState', {
                    get: function get() {
                        return {
                            completed: 'connected',
                            checking: 'connecting'
                        }[this.iceConnectionState] || this.iceConnectionState;
                    },

                    enumerable: true,
                    configurable: true
                });
                Object.defineProperty(proto, 'onconnectionstatechange', {
                    get: function get() {
                        return this._onconnectionstatechange || null;
                    },
                    set: function set(cb) {
                        if (this._onconnectionstatechange) {
                            this.removeEventListener('connectionstatechange', this._onconnectionstatechange);
                            delete this._onconnectionstatechange;
                        }
                        if (cb) {
                            this.addEventListener('connectionstatechange', this._onconnectionstatechange = cb);
                        }
                    },

                    enumerable: true,
                    configurable: true
                });

                ['setLocalDescription', 'setRemoteDescription'].forEach(function (method) {
                    var origMethod = proto[method];
                    proto[method] = function () {
                        if (!this._connectionstatechangepoly) {
                            this._connectionstatechangepoly = function (e) {
                                var pc = e.target;
                                if (pc._lastConnectionState !== pc.connectionState) {
                                    pc._lastConnectionState = pc.connectionState;
                                    var newEvent = new Event('connectionstatechange', e);
                                    pc.dispatchEvent(newEvent);
                                }
                                return e;
                            };
                            this.addEventListener('iceconnectionstatechange', this._connectionstatechangepoly);
                        }
                        return origMethod.apply(this, arguments);
                    };
                });
            }

            function removeAllowExtmapMixed(window) {
                /* remove a=extmap-allow-mixed for Chrome < M71 */
                if (!window.RTCPeerConnection) {
                    return;
                }
                var browserDetails = utils.detectBrowser(window);
                if (browserDetails.browser === 'chrome' && browserDetails.version >= 71) {
                    return;
                }
                var nativeSRD = window.RTCPeerConnection.prototype.setRemoteDescription;
                window.RTCPeerConnection.prototype.setRemoteDescription = function setRemoteDescription(desc) {
                    if (desc && desc.sdp && desc.sdp.indexOf('\na=extmap-allow-mixed') !== -1) {
                        desc.sdp = desc.sdp.split('\n').filter(function (line) {
                            return line.trim() !== 'a=extmap-allow-mixed';
                        }).join('\n');
                    }
                    return nativeSRD.apply(this, arguments);
                };
            }

        }, {"./utils": 15, "sdp": 17}], 7: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.shimGetDisplayMedia = exports.shimGetUserMedia = undefined;

            var _getusermedia = require('./getusermedia');

            Object.defineProperty(exports, 'shimGetUserMedia', {
                enumerable: true,
                get: function get() {
                    return _getusermedia.shimGetUserMedia;
                }
            });

            var _getdisplaymedia = require('./getdisplaymedia');

            Object.defineProperty(exports, 'shimGetDisplayMedia', {
                enumerable: true,
                get: function get() {
                    return _getdisplaymedia.shimGetDisplayMedia;
                }
            });
            exports.shimPeerConnection = shimPeerConnection;
            exports.shimReplaceTrack = shimReplaceTrack;

            var _utils = require('../utils');

            var utils = _interopRequireWildcard(_utils);

            var _filtericeservers = require('./filtericeservers');

            var _rtcpeerconnectionShim = require('rtcpeerconnection-shim');

            var _rtcpeerconnectionShim2 = _interopRequireDefault(_rtcpeerconnectionShim);

            function _interopRequireDefault(obj) {
                return obj && obj.__esModule ? obj : {default: obj};
            }

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            function shimPeerConnection(window) {
                var browserDetails = utils.detectBrowser(window);

                if (window.RTCIceGatherer) {
                    if (!window.RTCIceCandidate) {
                        window.RTCIceCandidate = function RTCIceCandidate(args) {
                            return args;
                        };
                    }
                    if (!window.RTCSessionDescription) {
                        window.RTCSessionDescription = function RTCSessionDescription(args) {
                            return args;
                        };
                    }
                    // this adds an additional event listener to MediaStrackTrack that signals
                    // when a tracks enabled property was changed. Workaround for a bug in
                    // addStream, see below. No longer required in 15025+
                    if (browserDetails.version < 15025) {
                        var origMSTEnabled = Object.getOwnPropertyDescriptor(window.MediaStreamTrack.prototype, 'enabled');
                        Object.defineProperty(window.MediaStreamTrack.prototype, 'enabled', {
                            set: function set(value) {
                                origMSTEnabled.set.call(this, value);
                                var ev = new Event('enabled');
                                ev.enabled = value;
                                this.dispatchEvent(ev);
                            }
                        });
                    }
                }

                // ORTC defines the DTMF sender a bit different.
                // https://github.com/w3c/ortc/issues/714
                if (window.RTCRtpSender && !('dtmf' in window.RTCRtpSender.prototype)) {
                    Object.defineProperty(window.RTCRtpSender.prototype, 'dtmf', {
                        get: function get() {
                            if (this._dtmf === undefined) {
                                if (this.track.kind === 'audio') {
                                    this._dtmf = new window.RTCDtmfSender(this);
                                } else if (this.track.kind === 'video') {
                                    this._dtmf = null;
                                }
                            }
                            return this._dtmf;
                        }
                    });
                }
                // Edge currently only implements the RTCDtmfSender, not the
                // RTCDTMFSender alias. See http://draft.ortc.org/#rtcdtmfsender2*
                if (window.RTCDtmfSender && !window.RTCDTMFSender) {
                    window.RTCDTMFSender = window.RTCDtmfSender;
                }

                var RTCPeerConnectionShim = (0, _rtcpeerconnectionShim2.default)(window, browserDetails.version);
                window.RTCPeerConnection = function RTCPeerConnection(config) {
                    if (config && config.iceServers) {
                        config.iceServers = (0, _filtericeservers.filterIceServers)(config.iceServers, browserDetails.version);
                        utils.log('ICE servers after filtering:', config.iceServers);
                    }
                    return new RTCPeerConnectionShim(config);
                };
                window.RTCPeerConnection.prototype = RTCPeerConnectionShim.prototype;
            }

            function shimReplaceTrack(window) {
                // ORTC has replaceTrack -- https://github.com/w3c/ortc/issues/614
                if (window.RTCRtpSender && !('replaceTrack' in window.RTCRtpSender.prototype)) {
                    window.RTCRtpSender.prototype.replaceTrack = window.RTCRtpSender.prototype.setTrack;
                }
            }

        }, {
            "../utils": 15,
            "./filtericeservers": 8,
            "./getdisplaymedia": 9,
            "./getusermedia": 10,
            "rtcpeerconnection-shim": 16
        }], 8: [function (require, module, exports) {
            /*
   *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.filterIceServers = filterIceServers;

            var _utils = require('../utils');

            var utils = _interopRequireWildcard(_utils);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            // Edge does not like
            // 1) stun: filtered after 14393 unless ?transport=udp is present
            // 2) turn: that does not have all of turn:host:port?transport=udp
            // 3) turn: with ipv6 addresses
            // 4) turn: occurring muliple times
            function filterIceServers(iceServers, edgeVersion) {
                var hasTurn = false;
                iceServers = JSON.parse(JSON.stringify(iceServers));
                return iceServers.filter(function (server) {
                    if (server && (server.urls || server.url)) {
                        var urls = server.urls || server.url;
                        if (server.url && !server.urls) {
                            utils.deprecated('RTCIceServer.url', 'RTCIceServer.urls');
                        }
                        var isString = typeof urls === 'string';
                        if (isString) {
                            urls = [urls];
                        }
                        urls = urls.filter(function (url) {
                            // filter STUN unconditionally.
                            if (url.indexOf('stun:') === 0) {
                                return false;
                            }

                            var validTurn = url.startsWith('turn') && !url.startsWith('turn:[') && url.includes('transport=udp');
                            if (validTurn && !hasTurn) {
                                hasTurn = true;
                                return true;
                            }
                            return validTurn && !hasTurn;
                        });

                        delete server.url;
                        server.urls = isString ? urls[0] : urls;
                        return !!urls.length;
                    }
                });
            }

        }, {"../utils": 15}], 9: [function (require, module, exports) {
            /*
   *  Copyright (c) 2018 The adapter.js project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.shimGetDisplayMedia = shimGetDisplayMedia;

            function shimGetDisplayMedia(window) {
                if (!('getDisplayMedia' in window.navigator)) {
                    return;
                }
                if (!window.navigator.mediaDevices) {
                    return;
                }
                if (window.navigator.mediaDevices && 'getDisplayMedia' in window.navigator.mediaDevices) {
                    return;
                }
                window.navigator.mediaDevices.getDisplayMedia = window.navigator.getDisplayMedia.bind(window.navigator);
            }

        }, {}], 10: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.shimGetUserMedia = shimGetUserMedia;

            function shimGetUserMedia(window) {
                var navigator = window && window.navigator;

                var shimError_ = function shimError_(e) {
                    return {
                        name: {PermissionDeniedError: 'NotAllowedError'}[e.name] || e.name,
                        message: e.message,
                        constraint: e.constraint,
                        toString: function toString() {
                            return this.name;
                        }
                    };
                };

                // getUserMedia error shim.
                var origGetUserMedia = navigator.mediaDevices.getUserMedia.bind(navigator.mediaDevices);
                navigator.mediaDevices.getUserMedia = function (c) {
                    return origGetUserMedia(c).catch(function (e) {
                        return Promise.reject(shimError_(e));
                    });
                };
            }

        }, {}], 11: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.shimGetDisplayMedia = exports.shimGetUserMedia = undefined;

            var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
                return typeof obj;
            } : function (obj) {
                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
            };

            var _getusermedia = require('./getusermedia');

            Object.defineProperty(exports, 'shimGetUserMedia', {
                enumerable: true,
                get: function get() {
                    return _getusermedia.shimGetUserMedia;
                }
            });

            var _getdisplaymedia = require('./getdisplaymedia');

            Object.defineProperty(exports, 'shimGetDisplayMedia', {
                enumerable: true,
                get: function get() {
                    return _getdisplaymedia.shimGetDisplayMedia;
                }
            });
            exports.shimOnTrack = shimOnTrack;
            exports.shimPeerConnection = shimPeerConnection;
            exports.shimSenderGetStats = shimSenderGetStats;
            exports.shimReceiverGetStats = shimReceiverGetStats;
            exports.shimRemoveStream = shimRemoveStream;
            exports.shimRTCDataChannel = shimRTCDataChannel;
            exports.shimAddTransceiver = shimAddTransceiver;
            exports.shimCreateOffer = shimCreateOffer;
            exports.shimCreateAnswer = shimCreateAnswer;

            var _utils = require('../utils');

            var utils = _interopRequireWildcard(_utils);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            function _defineProperty(obj, key, value) {
                if (key in obj) {
                    Object.defineProperty(obj, key, {
                        value: value,
                        enumerable: true,
                        configurable: true,
                        writable: true
                    });
                } else {
                    obj[key] = value;
                }
                return obj;
            }

            function shimOnTrack(window) {
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCTrackEvent && 'receiver' in window.RTCTrackEvent.prototype && !('transceiver' in window.RTCTrackEvent.prototype)) {
                    Object.defineProperty(window.RTCTrackEvent.prototype, 'transceiver', {
                        get: function get() {
                            return {receiver: this.receiver};
                        }
                    });
                }
            }

            function shimPeerConnection(window) {
                var browserDetails = utils.detectBrowser(window);

                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) !== 'object' || !(window.RTCPeerConnection || window.mozRTCPeerConnection)) {
                    return; // probably media.peerconnection.enabled=false in about:config
                }
                if (!window.RTCPeerConnection && window.mozRTCPeerConnection) {
                    // very basic support for old versions.
                    window.RTCPeerConnection = window.mozRTCPeerConnection;
                }

                if (browserDetails.version < 53) {
                    // shim away need for obsolete RTCIceCandidate/RTCSessionDescription.
                    ['setLocalDescription', 'setRemoteDescription', 'addIceCandidate'].forEach(function (method) {
                        var nativeMethod = window.RTCPeerConnection.prototype[method];
                        var methodObj = _defineProperty({}, method, function () {
                            arguments[0] = new (method === 'addIceCandidate' ? window.RTCIceCandidate : window.RTCSessionDescription)(arguments[0]);
                            return nativeMethod.apply(this, arguments);
                        });
                        window.RTCPeerConnection.prototype[method] = methodObj[method];
                    });
                }

                // support for addIceCandidate(null or undefined)
                // as well as ignoring {sdpMid, candidate: ""}
                if (browserDetails.version < 68) {
                    var nativeAddIceCandidate = window.RTCPeerConnection.prototype.addIceCandidate;
                    window.RTCPeerConnection.prototype.addIceCandidate = function addIceCandidate() {
                        if (!arguments[0]) {
                            if (arguments[1]) {
                                arguments[1].apply(null);
                            }
                            return Promise.resolve();
                        }
                        // Firefox 68+ emits and processes {candidate: "", ...}, ignore
                        // in older versions.
                        if (arguments[0] && arguments[0].candidate === '') {
                            return Promise.resolve();
                        }
                        return nativeAddIceCandidate.apply(this, arguments);
                    };
                }

                var modernStatsTypes = {
                    inboundrtp: 'inbound-rtp',
                    outboundrtp: 'outbound-rtp',
                    candidatepair: 'candidate-pair',
                    localcandidate: 'local-candidate',
                    remotecandidate: 'remote-candidate'
                };

                var nativeGetStats = window.RTCPeerConnection.prototype.getStats;
                window.RTCPeerConnection.prototype.getStats = function getStats() {
                    var _arguments = Array.prototype.slice.call(arguments),
                        selector = _arguments[0],
                        onSucc = _arguments[1],
                        onErr = _arguments[2];

                    return nativeGetStats.apply(this, [selector || null]).then(function (stats) {
                        if (browserDetails.version < 53 && !onSucc) {
                            // Shim only promise getStats with spec-hyphens in type names
                            // Leave callback version alone; misc old uses of forEach before Map
                            try {
                                stats.forEach(function (stat) {
                                    stat.type = modernStatsTypes[stat.type] || stat.type;
                                });
                            } catch (e) {
                                if (e.name !== 'TypeError') {
                                    throw e;
                                }
                                // Avoid TypeError: "type" is read-only, in old versions. 34-43ish
                                stats.forEach(function (stat, i) {
                                    stats.set(i, Object.assign({}, stat, {
                                        type: modernStatsTypes[stat.type] || stat.type
                                    }));
                                });
                            }
                        }
                        return stats;
                    }).then(onSucc, onErr);
                };
            }

            function shimSenderGetStats(window) {
                if (!((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection && window.RTCRtpSender)) {
                    return;
                }
                if (window.RTCRtpSender && 'getStats' in window.RTCRtpSender.prototype) {
                    return;
                }
                var origGetSenders = window.RTCPeerConnection.prototype.getSenders;
                if (origGetSenders) {
                    window.RTCPeerConnection.prototype.getSenders = function getSenders() {
                        var _this = this;

                        var senders = origGetSenders.apply(this, []);
                        senders.forEach(function (sender) {
                            return sender._pc = _this;
                        });
                        return senders;
                    };
                }

                var origAddTrack = window.RTCPeerConnection.prototype.addTrack;
                if (origAddTrack) {
                    window.RTCPeerConnection.prototype.addTrack = function addTrack() {
                        var sender = origAddTrack.apply(this, arguments);
                        sender._pc = this;
                        return sender;
                    };
                }
                window.RTCRtpSender.prototype.getStats = function getStats() {
                    return this.track ? this._pc.getStats(this.track) : Promise.resolve(new Map());
                };
            }

            function shimReceiverGetStats(window) {
                if (!((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection && window.RTCRtpSender)) {
                    return;
                }
                if (window.RTCRtpSender && 'getStats' in window.RTCRtpReceiver.prototype) {
                    return;
                }
                var origGetReceivers = window.RTCPeerConnection.prototype.getReceivers;
                if (origGetReceivers) {
                    window.RTCPeerConnection.prototype.getReceivers = function getReceivers() {
                        var _this2 = this;

                        var receivers = origGetReceivers.apply(this, []);
                        receivers.forEach(function (receiver) {
                            return receiver._pc = _this2;
                        });
                        return receivers;
                    };
                }
                utils.wrapPeerConnectionEvent(window, 'track', function (e) {
                    e.receiver._pc = e.srcElement;
                    return e;
                });
                window.RTCRtpReceiver.prototype.getStats = function getStats() {
                    return this._pc.getStats(this.track);
                };
            }

            function shimRemoveStream(window) {
                if (!window.RTCPeerConnection || 'removeStream' in window.RTCPeerConnection.prototype) {
                    return;
                }
                window.RTCPeerConnection.prototype.removeStream = function removeStream(stream) {
                    var _this3 = this;

                    utils.deprecated('removeStream', 'removeTrack');
                    this.getSenders().forEach(function (sender) {
                        if (sender.track && stream.getTracks().includes(sender.track)) {
                            _this3.removeTrack(sender);
                        }
                    });
                };
            }

            function shimRTCDataChannel(window) {
                // rename DataChannel to RTCDataChannel (native fix in FF60):
                // https://bugzilla.mozilla.org/show_bug.cgi?id=1173851
                if (window.DataChannel && !window.RTCDataChannel) {
                    window.RTCDataChannel = window.DataChannel;
                }
            }

            function shimAddTransceiver(window) {
                // https://github.com/webrtcHacks/adapter/issues/998#issuecomment-516921647
                // Firefox ignores the init sendEncodings options passed to addTransceiver
                // https://bugzilla.mozilla.org/show_bug.cgi?id=1396918
                if (!((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection)) {
                    return;
                }
                var origAddTransceiver = window.RTCPeerConnection.prototype.addTransceiver;
                if (origAddTransceiver) {
                    window.RTCPeerConnection.prototype.addTransceiver = function addTransceiver() {
                        this.setParametersPromises = [];
                        var initParameters = arguments[1];
                        var shouldPerformCheck = initParameters && 'sendEncodings' in initParameters;
                        if (shouldPerformCheck) {
                            // If sendEncodings params are provided, validate grammar
                            initParameters.sendEncodings.forEach(function (encodingParam) {
                                if ('rid' in encodingParam) {
                                    var ridRegex = /^[a-z0-9]{0,16}$/i;
                                    if (!ridRegex.test(encodingParam.rid)) {
                                        throw new TypeError('Invalid RID value provided.');
                                    }
                                }
                                if ('scaleResolutionDownBy' in encodingParam) {
                                    if (!(parseFloat(encodingParam.scaleResolutionDownBy) >= 1.0)) {
                                        throw new RangeError('scale_resolution_down_by must be >= 1.0');
                                    }
                                }
                                if ('maxFramerate' in encodingParam) {
                                    if (!(parseFloat(encodingParam.maxFramerate) >= 0)) {
                                        throw new RangeError('max_framerate must be >= 0.0');
                                    }
                                }
                            });
                        }
                        var transceiver = origAddTransceiver.apply(this, arguments);
                        if (shouldPerformCheck) {
                            // Check if the init options were applied. If not we do this in an
                            // asynchronous way and save the promise reference in a global object.
                            // This is an ugly hack, but at the same time is way more robust than
                            // checking the sender parameters before and after the createOffer
                            // Also note that after the createoffer we are not 100% sure that
                            // the params were asynchronously applied so we might miss the
                            // opportunity to recreate offer.
                            var sender = transceiver.sender;

                            var params = sender.getParameters();
                            if (!('encodings' in params)) {
                                params.encodings = initParameters.sendEncodings;
                                this.setParametersPromises.push(sender.setParameters(params).catch(function () {
                                }));
                            }
                        }
                        return transceiver;
                    };
                }
            }

            function shimCreateOffer(window) {
                // https://github.com/webrtcHacks/adapter/issues/998#issuecomment-516921647
                // Firefox ignores the init sendEncodings options passed to addTransceiver
                // https://bugzilla.mozilla.org/show_bug.cgi?id=1396918
                if (!((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection)) {
                    return;
                }
                var origCreateOffer = window.RTCPeerConnection.prototype.createOffer;
                window.RTCPeerConnection.prototype.createOffer = function createOffer() {
                    var _this4 = this,
                        _arguments2 = arguments;

                    if (this.setParametersPromises && this.setParametersPromises.length) {
                        return Promise.all(this.setParametersPromises).then(function () {
                            return origCreateOffer.apply(_this4, _arguments2);
                        }).finally(function () {
                            _this4.setParametersPromises = [];
                        });
                    }
                    return origCreateOffer.apply(this, arguments);
                };
            }

            function shimCreateAnswer(window) {
                // https://github.com/webrtcHacks/adapter/issues/998#issuecomment-516921647
                // Firefox ignores the init sendEncodings options passed to addTransceiver
                // https://bugzilla.mozilla.org/show_bug.cgi?id=1396918
                if (!((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCPeerConnection)) {
                    return;
                }
                var origCreateAnswer = window.RTCPeerConnection.prototype.createAnswer;
                window.RTCPeerConnection.prototype.createAnswer = function createAnswer() {
                    var _this5 = this,
                        _arguments3 = arguments;

                    if (this.setParametersPromises && this.setParametersPromises.length) {
                        return Promise.all(this.setParametersPromises).then(function () {
                            return origCreateAnswer.apply(_this5, _arguments3);
                        }).finally(function () {
                            _this5.setParametersPromises = [];
                        });
                    }
                    return origCreateAnswer.apply(this, arguments);
                };
            }

        }, {"../utils": 15, "./getdisplaymedia": 12, "./getusermedia": 13}], 12: [function (require, module, exports) {
            /*
   *  Copyright (c) 2018 The adapter.js project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });
            exports.shimGetDisplayMedia = shimGetDisplayMedia;

            function shimGetDisplayMedia(window, preferredMediaSource) {
                if (window.navigator.mediaDevices && 'getDisplayMedia' in window.navigator.mediaDevices) {
                    return;
                }
                if (!window.navigator.mediaDevices) {
                    return;
                }
                window.navigator.mediaDevices.getDisplayMedia = function getDisplayMedia(constraints) {
                    if (!(constraints && constraints.video)) {
                        var err = new DOMException('getDisplayMedia without video ' + 'constraints is undefined');
                        err.name = 'NotFoundError';
                        // from https://heycam.github.io/webidl/#idl-DOMException-error-names
                        err.code = 8;
                        return Promise.reject(err);
                    }
                    if (constraints.video === true) {
                        constraints.video = {mediaSource: preferredMediaSource};
                    } else {
                        constraints.video.mediaSource = preferredMediaSource;
                    }
                    return window.navigator.mediaDevices.getUserMedia(constraints);
                };
            }

        }, {}], 13: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });

            var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
                return typeof obj;
            } : function (obj) {
                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
            };

            exports.shimGetUserMedia = shimGetUserMedia;

            var _utils = require('../utils');

            var utils = _interopRequireWildcard(_utils);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            function shimGetUserMedia(window) {
                var browserDetails = utils.detectBrowser(window);
                var navigator = window && window.navigator;
                var MediaStreamTrack = window && window.MediaStreamTrack;

                navigator.getUserMedia = function (constraints, onSuccess, onError) {
                    // Replace Firefox 44+'s deprecation warning with unprefixed version.
                    utils.deprecated('navigator.getUserMedia', 'navigator.mediaDevices.getUserMedia');
                    navigator.mediaDevices.getUserMedia(constraints).then(onSuccess, onError);
                };

                if (!(browserDetails.version > 55 && 'autoGainControl' in navigator.mediaDevices.getSupportedConstraints())) {
                    var remap = function remap(obj, a, b) {
                        if (a in obj && !(b in obj)) {
                            obj[b] = obj[a];
                            delete obj[a];
                        }
                    };

                    var nativeGetUserMedia = navigator.mediaDevices.getUserMedia.bind(navigator.mediaDevices);
                    navigator.mediaDevices.getUserMedia = function (c) {
                        if ((typeof c === 'undefined' ? 'undefined' : _typeof(c)) === 'object' && _typeof(c.audio) === 'object') {
                            c = JSON.parse(JSON.stringify(c));
                            remap(c.audio, 'autoGainControl', 'mozAutoGainControl');
                            remap(c.audio, 'noiseSuppression', 'mozNoiseSuppression');
                        }
                        return nativeGetUserMedia(c);
                    };

                    if (MediaStreamTrack && MediaStreamTrack.prototype.getSettings) {
                        var nativeGetSettings = MediaStreamTrack.prototype.getSettings;
                        MediaStreamTrack.prototype.getSettings = function () {
                            var obj = nativeGetSettings.apply(this, arguments);
                            remap(obj, 'mozAutoGainControl', 'autoGainControl');
                            remap(obj, 'mozNoiseSuppression', 'noiseSuppression');
                            return obj;
                        };
                    }

                    if (MediaStreamTrack && MediaStreamTrack.prototype.applyConstraints) {
                        var nativeApplyConstraints = MediaStreamTrack.prototype.applyConstraints;
                        MediaStreamTrack.prototype.applyConstraints = function (c) {
                            if (this.kind === 'audio' && (typeof c === 'undefined' ? 'undefined' : _typeof(c)) === 'object') {
                                c = JSON.parse(JSON.stringify(c));
                                remap(c, 'autoGainControl', 'mozAutoGainControl');
                                remap(c, 'noiseSuppression', 'mozNoiseSuppression');
                            }
                            return nativeApplyConstraints.apply(this, [c]);
                        };
                    }
                }
            }

        }, {"../utils": 15}], 14: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });

            var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
                return typeof obj;
            } : function (obj) {
                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
            };

            exports.shimLocalStreamsAPI = shimLocalStreamsAPI;
            exports.shimRemoteStreamsAPI = shimRemoteStreamsAPI;
            exports.shimCallbacksAPI = shimCallbacksAPI;
            exports.shimGetUserMedia = shimGetUserMedia;
            exports.shimConstraints = shimConstraints;
            exports.shimRTCIceServerUrls = shimRTCIceServerUrls;
            exports.shimTrackEventTransceiver = shimTrackEventTransceiver;
            exports.shimCreateOfferLegacy = shimCreateOfferLegacy;

            var _utils = require('../utils');

            var utils = _interopRequireWildcard(_utils);

            function _interopRequireWildcard(obj) {
                if (obj && obj.__esModule) {
                    return obj;
                } else {
                    var newObj = {};
                    if (obj != null) {
                        for (var key in obj) {
                            if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
                        }
                    }
                    newObj.default = obj;
                    return newObj;
                }
            }

            function shimLocalStreamsAPI(window) {
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) !== 'object' || !window.RTCPeerConnection) {
                    return;
                }
                if (!('getLocalStreams' in window.RTCPeerConnection.prototype)) {
                    window.RTCPeerConnection.prototype.getLocalStreams = function getLocalStreams() {
                        if (!this._localStreams) {
                            this._localStreams = [];
                        }
                        return this._localStreams;
                    };
                }
                if (!('addStream' in window.RTCPeerConnection.prototype)) {
                    var _addTrack = window.RTCPeerConnection.prototype.addTrack;
                    window.RTCPeerConnection.prototype.addStream = function addStream(stream) {
                        var _this = this;

                        if (!this._localStreams) {
                            this._localStreams = [];
                        }
                        if (!this._localStreams.includes(stream)) {
                            this._localStreams.push(stream);
                        }
                        // Try to emulate Chrome's behaviour of adding in audio-video order.
                        // Safari orders by track id.
                        stream.getAudioTracks().forEach(function (track) {
                            return _addTrack.call(_this, track, stream);
                        });
                        stream.getVideoTracks().forEach(function (track) {
                            return _addTrack.call(_this, track, stream);
                        });
                    };

                    window.RTCPeerConnection.prototype.addTrack = function addTrack(track) {
                        var stream = arguments[1];
                        if (stream) {
                            if (!this._localStreams) {
                                this._localStreams = [stream];
                            } else if (!this._localStreams.includes(stream)) {
                                this._localStreams.push(stream);
                            }
                        }
                        return _addTrack.apply(this, arguments);
                    };
                }
                if (!('removeStream' in window.RTCPeerConnection.prototype)) {
                    window.RTCPeerConnection.prototype.removeStream = function removeStream(stream) {
                        var _this2 = this;

                        if (!this._localStreams) {
                            this._localStreams = [];
                        }
                        var index = this._localStreams.indexOf(stream);
                        if (index === -1) {
                            return;
                        }
                        this._localStreams.splice(index, 1);
                        var tracks = stream.getTracks();
                        this.getSenders().forEach(function (sender) {
                            if (tracks.includes(sender.track)) {
                                _this2.removeTrack(sender);
                            }
                        });
                    };
                }
            }

            function shimRemoteStreamsAPI(window) {
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) !== 'object' || !window.RTCPeerConnection) {
                    return;
                }
                if (!('getRemoteStreams' in window.RTCPeerConnection.prototype)) {
                    window.RTCPeerConnection.prototype.getRemoteStreams = function getRemoteStreams() {
                        return this._remoteStreams ? this._remoteStreams : [];
                    };
                }
                if (!('onaddstream' in window.RTCPeerConnection.prototype)) {
                    Object.defineProperty(window.RTCPeerConnection.prototype, 'onaddstream', {
                        get: function get() {
                            return this._onaddstream;
                        },
                        set: function set(f) {
                            var _this3 = this;

                            if (this._onaddstream) {
                                this.removeEventListener('addstream', this._onaddstream);
                                this.removeEventListener('track', this._onaddstreampoly);
                            }
                            this.addEventListener('addstream', this._onaddstream = f);
                            this.addEventListener('track', this._onaddstreampoly = function (e) {
                                e.streams.forEach(function (stream) {
                                    if (!_this3._remoteStreams) {
                                        _this3._remoteStreams = [];
                                    }
                                    if (_this3._remoteStreams.includes(stream)) {
                                        return;
                                    }
                                    _this3._remoteStreams.push(stream);
                                    var event = new Event('addstream');
                                    event.stream = stream;
                                    _this3.dispatchEvent(event);
                                });
                            });
                        }
                    });
                    var origSetRemoteDescription = window.RTCPeerConnection.prototype.setRemoteDescription;
                    window.RTCPeerConnection.prototype.setRemoteDescription = function setRemoteDescription() {
                        var pc = this;
                        if (!this._onaddstreampoly) {
                            this.addEventListener('track', this._onaddstreampoly = function (e) {
                                e.streams.forEach(function (stream) {
                                    if (!pc._remoteStreams) {
                                        pc._remoteStreams = [];
                                    }
                                    if (pc._remoteStreams.indexOf(stream) >= 0) {
                                        return;
                                    }
                                    pc._remoteStreams.push(stream);
                                    var event = new Event('addstream');
                                    event.stream = stream;
                                    pc.dispatchEvent(event);
                                });
                            });
                        }
                        return origSetRemoteDescription.apply(pc, arguments);
                    };
                }
            }

            function shimCallbacksAPI(window) {
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) !== 'object' || !window.RTCPeerConnection) {
                    return;
                }
                var prototype = window.RTCPeerConnection.prototype;
                var origCreateOffer = prototype.createOffer;
                var origCreateAnswer = prototype.createAnswer;
                var setLocalDescription = prototype.setLocalDescription;
                var setRemoteDescription = prototype.setRemoteDescription;
                var addIceCandidate = prototype.addIceCandidate;

                prototype.createOffer = function createOffer(successCallback, failureCallback) {
                    var options = arguments.length >= 2 ? arguments[2] : arguments[0];
                    var promise = origCreateOffer.apply(this, [options]);
                    if (!failureCallback) {
                        return promise;
                    }
                    promise.then(successCallback, failureCallback);
                    return Promise.resolve();
                };

                prototype.createAnswer = function createAnswer(successCallback, failureCallback) {
                    var options = arguments.length >= 2 ? arguments[2] : arguments[0];
                    var promise = origCreateAnswer.apply(this, [options]);
                    if (!failureCallback) {
                        return promise;
                    }
                    promise.then(successCallback, failureCallback);
                    return Promise.resolve();
                };

                var withCallback = function withCallback(description, successCallback, failureCallback) {
                    var promise = setLocalDescription.apply(this, [description]);
                    if (!failureCallback) {
                        return promise;
                    }
                    promise.then(successCallback, failureCallback);
                    return Promise.resolve();
                };
                prototype.setLocalDescription = withCallback;

                withCallback = function withCallback(description, successCallback, failureCallback) {
                    var promise = setRemoteDescription.apply(this, [description]);
                    if (!failureCallback) {
                        return promise;
                    }
                    promise.then(successCallback, failureCallback);
                    return Promise.resolve();
                };
                prototype.setRemoteDescription = withCallback;

                withCallback = function withCallback(candidate, successCallback, failureCallback) {
                    var promise = addIceCandidate.apply(this, [candidate]);
                    if (!failureCallback) {
                        return promise;
                    }
                    promise.then(successCallback, failureCallback);
                    return Promise.resolve();
                };
                prototype.addIceCandidate = withCallback;
            }

            function shimGetUserMedia(window) {
                var navigator = window && window.navigator;

                if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
                    // shim not needed in Safari 12.1
                    var mediaDevices = navigator.mediaDevices;
                    var _getUserMedia = mediaDevices.getUserMedia.bind(mediaDevices);
                    navigator.mediaDevices.getUserMedia = function (constraints) {
                        return _getUserMedia(shimConstraints(constraints));
                    };
                }

                if (!navigator.getUserMedia && navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
                    navigator.getUserMedia = function getUserMedia(constraints, cb, errcb) {
                        navigator.mediaDevices.getUserMedia(constraints).then(cb, errcb);
                    }.bind(navigator);
                }
            }

            function shimConstraints(constraints) {
                if (constraints && constraints.video !== undefined) {
                    return Object.assign({}, constraints, {video: utils.compactObject(constraints.video)});
                }

                return constraints;
            }

            function shimRTCIceServerUrls(window) {
                // migrate from non-spec RTCIceServer.url to RTCIceServer.urls
                var OrigPeerConnection = window.RTCPeerConnection;
                window.RTCPeerConnection = function RTCPeerConnection(pcConfig, pcConstraints) {
                    if (pcConfig && pcConfig.iceServers) {
                        var newIceServers = [];
                        for (var i = 0; i < pcConfig.iceServers.length; i++) {
                            var server = pcConfig.iceServers[i];
                            if (!server.hasOwnProperty('urls') && server.hasOwnProperty('url')) {
                                utils.deprecated('RTCIceServer.url', 'RTCIceServer.urls');
                                server = JSON.parse(JSON.stringify(server));
                                server.urls = server.url;
                                delete server.url;
                                newIceServers.push(server);
                            } else {
                                newIceServers.push(pcConfig.iceServers[i]);
                            }
                        }
                        pcConfig.iceServers = newIceServers;
                    }
                    return new OrigPeerConnection(pcConfig, pcConstraints);
                };
                window.RTCPeerConnection.prototype = OrigPeerConnection.prototype;
                // wrap static methods. Currently just generateCertificate.
                if ('generateCertificate' in window.RTCPeerConnection) {
                    Object.defineProperty(window.RTCPeerConnection, 'generateCertificate', {
                        get: function get() {
                            return OrigPeerConnection.generateCertificate;
                        }
                    });
                }
            }

            function shimTrackEventTransceiver(window) {
                // Add event.transceiver member over deprecated event.receiver
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCTrackEvent && 'receiver' in window.RTCTrackEvent.prototype && !('transceiver' in window.RTCTrackEvent.prototype)) {
                    Object.defineProperty(window.RTCTrackEvent.prototype, 'transceiver', {
                        get: function get() {
                            return {receiver: this.receiver};
                        }
                    });
                }
            }

            function shimCreateOfferLegacy(window) {
                var origCreateOffer = window.RTCPeerConnection.prototype.createOffer;
                window.RTCPeerConnection.prototype.createOffer = function createOffer(offerOptions) {
                    if (offerOptions) {
                        if (typeof offerOptions.offerToReceiveAudio !== 'undefined') {
                            // support bit values
                            offerOptions.offerToReceiveAudio = !!offerOptions.offerToReceiveAudio;
                        }
                        var audioTransceiver = this.getTransceivers().find(function (transceiver) {
                            return transceiver.receiver.track.kind === 'audio';
                        });
                        if (offerOptions.offerToReceiveAudio === false && audioTransceiver) {
                            if (audioTransceiver.direction === 'sendrecv') {
                                if (audioTransceiver.setDirection) {
                                    audioTransceiver.setDirection('sendonly');
                                } else {
                                    audioTransceiver.direction = 'sendonly';
                                }
                            } else if (audioTransceiver.direction === 'recvonly') {
                                if (audioTransceiver.setDirection) {
                                    audioTransceiver.setDirection('inactive');
                                } else {
                                    audioTransceiver.direction = 'inactive';
                                }
                            }
                        } else if (offerOptions.offerToReceiveAudio === true && !audioTransceiver) {
                            this.addTransceiver('audio');
                        }

                        if (typeof offerOptions.offerToReceiveVideo !== 'undefined') {
                            // support bit values
                            offerOptions.offerToReceiveVideo = !!offerOptions.offerToReceiveVideo;
                        }
                        var videoTransceiver = this.getTransceivers().find(function (transceiver) {
                            return transceiver.receiver.track.kind === 'video';
                        });
                        if (offerOptions.offerToReceiveVideo === false && videoTransceiver) {
                            if (videoTransceiver.direction === 'sendrecv') {
                                if (videoTransceiver.setDirection) {
                                    videoTransceiver.setDirection('sendonly');
                                } else {
                                    videoTransceiver.direction = 'sendonly';
                                }
                            } else if (videoTransceiver.direction === 'recvonly') {
                                if (videoTransceiver.setDirection) {
                                    videoTransceiver.setDirection('inactive');
                                } else {
                                    videoTransceiver.direction = 'inactive';
                                }
                            }
                        } else if (offerOptions.offerToReceiveVideo === true && !videoTransceiver) {
                            this.addTransceiver('video');
                        }
                    }
                    return origCreateOffer.apply(this, arguments);
                };
            }

        }, {"../utils": 15}], 15: [function (require, module, exports) {
            /*
   *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            Object.defineProperty(exports, "__esModule", {
                value: true
            });

            var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
                return typeof obj;
            } : function (obj) {
                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
            };

            exports.extractVersion = extractVersion;
            exports.wrapPeerConnectionEvent = wrapPeerConnectionEvent;
            exports.disableLog = disableLog;
            exports.disableWarnings = disableWarnings;
            exports.log = log;
            exports.deprecated = deprecated;
            exports.detectBrowser = detectBrowser;
            exports.compactObject = compactObject;
            exports.walkStats = walkStats;
            exports.filterStats = filterStats;

            function _defineProperty(obj, key, value) {
                if (key in obj) {
                    Object.defineProperty(obj, key, {
                        value: value,
                        enumerable: true,
                        configurable: true,
                        writable: true
                    });
                } else {
                    obj[key] = value;
                }
                return obj;
            }

            var logDisabled_ = true;
            var deprecationWarnings_ = true;

            /**
             * Extract browser version out of the provided user agent string.
             *
             * @param {!string} uastring userAgent string.
             * @param {!string} expr Regular expression used as match criteria.
             * @param {!number} pos position in the version string to be returned.
             * @return {!number} browser version.
             */
            function extractVersion(uastring, expr, pos) {
                var match = uastring.match(expr);
                return match && match.length >= pos && parseInt(match[pos], 10);
            }

            // Wraps the peerconnection event eventNameToWrap in a function
            // which returns the modified event object (or false to prevent
            // the event).
            function wrapPeerConnectionEvent(window, eventNameToWrap, wrapper) {
                if (!window.RTCPeerConnection) {
                    return;
                }
                var proto = window.RTCPeerConnection.prototype;
                var nativeAddEventListener = proto.addEventListener;
                proto.addEventListener = function (nativeEventName, cb) {
                    if (nativeEventName !== eventNameToWrap) {
                        return nativeAddEventListener.apply(this, arguments);
                    }
                    var wrappedCallback = function wrappedCallback(e) {
                        var modifiedEvent = wrapper(e);
                        if (modifiedEvent) {
                            cb(modifiedEvent);
                        }
                    };
                    this._eventMap = this._eventMap || {};
                    this._eventMap[cb] = wrappedCallback;
                    return nativeAddEventListener.apply(this, [nativeEventName, wrappedCallback]);
                };

                var nativeRemoveEventListener = proto.removeEventListener;
                proto.removeEventListener = function (nativeEventName, cb) {
                    if (nativeEventName !== eventNameToWrap || !this._eventMap || !this._eventMap[cb]) {
                        return nativeRemoveEventListener.apply(this, arguments);
                    }
                    var unwrappedCb = this._eventMap[cb];
                    delete this._eventMap[cb];
                    return nativeRemoveEventListener.apply(this, [nativeEventName, unwrappedCb]);
                };

                Object.defineProperty(proto, 'on' + eventNameToWrap, {
                    get: function get() {
                        return this['_on' + eventNameToWrap];
                    },
                    set: function set(cb) {
                        if (this['_on' + eventNameToWrap]) {
                            this.removeEventListener(eventNameToWrap, this['_on' + eventNameToWrap]);
                            delete this['_on' + eventNameToWrap];
                        }
                        if (cb) {
                            this.addEventListener(eventNameToWrap, this['_on' + eventNameToWrap] = cb);
                        }
                    },

                    enumerable: true,
                    configurable: true
                });
            }

            function disableLog(bool) {
                if (typeof bool !== 'boolean') {
                    return new Error('Argument type: ' + (typeof bool === 'undefined' ? 'undefined' : _typeof(bool)) + '. Please use a boolean.');
                }
                logDisabled_ = bool;
                return bool ? 'adapter.js logging disabled' : 'adapter.js logging enabled';
            }

            /**
             * Disable or enable deprecation warnings
             * @param {!boolean} bool set to true to disable warnings.
             */
            function disableWarnings(bool) {
                if (typeof bool !== 'boolean') {
                    return new Error('Argument type: ' + (typeof bool === 'undefined' ? 'undefined' : _typeof(bool)) + '. Please use a boolean.');
                }
                deprecationWarnings_ = !bool;
                return 'adapter.js deprecation warnings ' + (bool ? 'disabled' : 'enabled');
            }

            function log() {
                if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object') {
                    if (logDisabled_) {
                        return;
                    }
                    if (typeof console !== 'undefined' && typeof console.log === 'function') {
                        console.log.apply(console, arguments);
                    }
                }
            }

            /**
             * Shows a deprecation warning suggesting the modern and spec-compatible API.
             */
            function deprecated(oldMethod, newMethod) {
                if (!deprecationWarnings_) {
                    return;
                }
                console.warn(oldMethod + ' is deprecated, please use ' + newMethod + ' instead.');
            }

            /**
             * Browser detector.
             *
             * @return {object} result containing browser and version
             *     properties.
             */
            function detectBrowser(window) {
                var navigator = window.navigator;

                // Returned result object.

                var result = {browser: null, version: null};

                // Fail early if it's not a browser
                if (typeof window === 'undefined' || !window.navigator) {
                    result.browser = 'Not a browser.';
                    return result;
                }

                if (navigator.mozGetUserMedia) {
                    // Firefox.
                    result.browser = 'firefox';
                    result.version = extractVersion(navigator.userAgent, /Firefox\/(\d+)\./, 1);
                } else if (navigator.webkitGetUserMedia || window.isSecureContext === false && window.webkitRTCPeerConnection && !window.RTCIceGatherer) {
                    // Chrome, Chromium, Webview, Opera.
                    // Version matches Chrome/WebRTC version.
                    // Chrome 74 removed webkitGetUserMedia on http as well so we need the
                    // more complicated fallback to webkitRTCPeerConnection.
                    result.browser = 'chrome';
                    result.version = extractVersion(navigator.userAgent, /Chrom(e|ium)\/(\d+)\./, 2);
                } else if (navigator.mediaDevices && navigator.userAgent.match(/Edge\/(\d+).(\d+)$/)) {
                    // Edge.
                    result.browser = 'edge';
                    result.version = extractVersion(navigator.userAgent, /Edge\/(\d+).(\d+)$/, 2);
                } else if (window.RTCPeerConnection && navigator.userAgent.match(/AppleWebKit\/(\d+)\./)) {
                    // Safari.
                    result.browser = 'safari';
                    result.version = extractVersion(navigator.userAgent, /AppleWebKit\/(\d+)\./, 1);
                    result.supportsUnifiedPlan = window.RTCRtpTransceiver && 'currentDirection' in window.RTCRtpTransceiver.prototype;
                } else {
                    // Default fallthrough: not supported.
                    result.browser = 'Not a supported browser.';
                    return result;
                }

                return result;
            }

            /**
             * Checks if something is an object.
             *
             * @param {*} val The something you want to check.
             * @return true if val is an object, false otherwise.
             */
            function isObject(val) {
                return Object.prototype.toString.call(val) === '[object Object]';
            }

            /**
             * Remove all empty objects and undefined values
             * from a nested object -- an enhanced and vanilla version
             * of Lodash's `compact`.
             */
            function compactObject(data) {
                if (!isObject(data)) {
                    return data;
                }

                return Object.keys(data).reduce(function (accumulator, key) {
                    var isObj = isObject(data[key]);
                    var value = isObj ? compactObject(data[key]) : data[key];
                    var isEmptyObject = isObj && !Object.keys(value).length;
                    if (value === undefined || isEmptyObject) {
                        return accumulator;
                    }
                    return Object.assign(accumulator, _defineProperty({}, key, value));
                }, {});
            }

            /* iterates the stats graph recursively. */
            function walkStats(stats, base, resultSet) {
                if (!base || resultSet.has(base.id)) {
                    return;
                }
                resultSet.set(base.id, base);
                Object.keys(base).forEach(function (name) {
                    if (name.endsWith('Id')) {
                        walkStats(stats, stats.get(base[name]), resultSet);
                    } else if (name.endsWith('Ids')) {
                        base[name].forEach(function (id) {
                            walkStats(stats, stats.get(id), resultSet);
                        });
                    }
                });
            }

            /* filter getStats for a sender/receiver track. */
            function filterStats(result, track, outbound) {
                var streamStatsType = outbound ? 'outbound-rtp' : 'inbound-rtp';
                var filteredResult = new Map();
                if (track === null) {
                    return filteredResult;
                }
                var trackStats = [];
                result.forEach(function (value) {
                    if (value.type === 'track' && value.trackIdentifier === track.id) {
                        trackStats.push(value);
                    }
                });
                trackStats.forEach(function (trackStat) {
                    result.forEach(function (stats) {
                        if (stats.type === streamStatsType && stats.trackId === trackStat.id) {
                            walkStats(result, stats, filteredResult);
                        }
                    });
                });
                return filteredResult;
            }

        }, {}], 16: [function (require, module, exports) {
            /*
   *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree.
   */
            /* eslint-env node */
            'use strict';

            var SDPUtils = require('sdp');

            function fixStatsType(stat) {
                return {
                    inboundrtp: 'inbound-rtp',
                    outboundrtp: 'outbound-rtp',
                    candidatepair: 'candidate-pair',
                    localcandidate: 'local-candidate',
                    remotecandidate: 'remote-candidate'
                }[stat.type] || stat.type;
            }

            function writeMediaSection(transceiver, caps, type, stream, dtlsRole) {
                var sdp = SDPUtils.writeRtpDescription(transceiver.kind, caps);

                // Map ICE parameters (ufrag, pwd) to SDP.
                sdp += SDPUtils.writeIceParameters(
                    transceiver.iceGatherer.getLocalParameters());

                // Map DTLS parameters to SDP.
                sdp += SDPUtils.writeDtlsParameters(
                    transceiver.dtlsTransport.getLocalParameters(),
                    type === 'offer' ? 'actpass' : dtlsRole || 'active');

                sdp += 'a=mid:' + transceiver.mid + '\r\n';

                if (transceiver.rtpSender && transceiver.rtpReceiver) {
                    sdp += 'a=sendrecv\r\n';
                } else if (transceiver.rtpSender) {
                    sdp += 'a=sendonly\r\n';
                } else if (transceiver.rtpReceiver) {
                    sdp += 'a=recvonly\r\n';
                } else {
                    sdp += 'a=inactive\r\n';
                }

                if (transceiver.rtpSender) {
                    var trackId = transceiver.rtpSender._initialTrackId ||
                        transceiver.rtpSender.track.id;
                    transceiver.rtpSender._initialTrackId = trackId;
                    // spec.
                    var msid = 'msid:' + (stream ? stream.id : '-') + ' ' +
                        trackId + '\r\n';
                    sdp += 'a=' + msid;
                    // for Chrome. Legacy should no longer be required.
                    sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].ssrc +
                        ' ' + msid;

                    // RTX
                    if (transceiver.sendEncodingParameters[0].rtx) {
                        sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].rtx.ssrc +
                            ' ' + msid;
                        sdp += 'a=ssrc-group:FID ' +
                            transceiver.sendEncodingParameters[0].ssrc + ' ' +
                            transceiver.sendEncodingParameters[0].rtx.ssrc +
                            '\r\n';
                    }
                }
                // FIXME: this should be written by writeRtpDescription.
                sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].ssrc +
                    ' cname:' + SDPUtils.localCName + '\r\n';
                if (transceiver.rtpSender && transceiver.sendEncodingParameters[0].rtx) {
                    sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].rtx.ssrc +
                        ' cname:' + SDPUtils.localCName + '\r\n';
                }
                return sdp;
            }

            // Edge does not like
            // 1) stun: filtered after 14393 unless ?transport=udp is present
            // 2) turn: that does not have all of turn:host:port?transport=udp
            // 3) turn: with ipv6 addresses
            // 4) turn: occurring muliple times
            function filterIceServers(iceServers, edgeVersion) {
                var hasTurn = false;
                iceServers = JSON.parse(JSON.stringify(iceServers));
                return iceServers.filter(function (server) {
                    if (server && (server.urls || server.url)) {
                        var urls = server.urls || server.url;
                        if (server.url && !server.urls) {
                            console.warn('RTCIceServer.url is deprecated! Use urls instead.');
                        }
                        var isString = typeof urls === 'string';
                        if (isString) {
                            urls = [urls];
                        }
                        urls = urls.filter(function (url) {
                            var validTurn = url.indexOf('turn:') === 0 &&
                                url.indexOf('transport=udp') !== -1 &&
                                url.indexOf('turn:[') === -1 &&
                                !hasTurn;

                            if (validTurn) {
                                hasTurn = true;
                                return true;
                            }
                            return url.indexOf('stun:') === 0 && edgeVersion >= 14393 &&
                                url.indexOf('?transport=udp') === -1;
                        });

                        delete server.url;
                        server.urls = isString ? urls[0] : urls;
                        return !!urls.length;
                    }
                });
            }

            // Determines the intersection of local and remote capabilities.
            function getCommonCapabilities(localCapabilities, remoteCapabilities) {
                var commonCapabilities = {
                    codecs: [],
                    headerExtensions: [],
                    fecMechanisms: []
                };

                var findCodecByPayloadType = function (pt, codecs) {
                    pt = parseInt(pt, 10);
                    for (var i = 0; i < codecs.length; i++) {
                        if (codecs[i].payloadType === pt ||
                            codecs[i].preferredPayloadType === pt) {
                            return codecs[i];
                        }
                    }
                };

                var rtxCapabilityMatches = function (lRtx, rRtx, lCodecs, rCodecs) {
                    var lCodec = findCodecByPayloadType(lRtx.parameters.apt, lCodecs);
                    var rCodec = findCodecByPayloadType(rRtx.parameters.apt, rCodecs);
                    return lCodec && rCodec &&
                        lCodec.name.toLowerCase() === rCodec.name.toLowerCase();
                };

                localCapabilities.codecs.forEach(function (lCodec) {
                    for (var i = 0; i < remoteCapabilities.codecs.length; i++) {
                        var rCodec = remoteCapabilities.codecs[i];
                        if (lCodec.name.toLowerCase() === rCodec.name.toLowerCase() &&
                            lCodec.clockRate === rCodec.clockRate) {
                            if (lCodec.name.toLowerCase() === 'rtx' &&
                                lCodec.parameters && rCodec.parameters.apt) {
                                // for RTX we need to find the local rtx that has a apt
                                // which points to the same local codec as the remote one.
                                if (!rtxCapabilityMatches(lCodec, rCodec,
                                    localCapabilities.codecs, remoteCapabilities.codecs)) {
                                    continue;
                                }
                            }
                            rCodec = JSON.parse(JSON.stringify(rCodec)); // deepcopy
                            // number of channels is the highest common number of channels
                            rCodec.numChannels = Math.min(lCodec.numChannels,
                                rCodec.numChannels);
                            // push rCodec so we reply with offerer payload type
                            commonCapabilities.codecs.push(rCodec);

                            // determine common feedback mechanisms
                            rCodec.rtcpFeedback = rCodec.rtcpFeedback.filter(function (fb) {
                                for (var j = 0; j < lCodec.rtcpFeedback.length; j++) {
                                    if (lCodec.rtcpFeedback[j].type === fb.type &&
                                        lCodec.rtcpFeedback[j].parameter === fb.parameter) {
                                        return true;
                                    }
                                }
                                return false;
                            });
                            // FIXME: also need to determine .parameters
                            //  see https://github.com/openpeer/ortc/issues/569
                            break;
                        }
                    }
                });

                localCapabilities.headerExtensions.forEach(function (lHeaderExtension) {
                    for (var i = 0; i < remoteCapabilities.headerExtensions.length;
                         i++) {
                        var rHeaderExtension = remoteCapabilities.headerExtensions[i];
                        if (lHeaderExtension.uri === rHeaderExtension.uri) {
                            commonCapabilities.headerExtensions.push(rHeaderExtension);
                            break;
                        }
                    }
                });

                // FIXME: fecMechanisms
                return commonCapabilities;
            }

            // is action=setLocalDescription with type allowed in signalingState
            function isActionAllowedInSignalingState(action, type, signalingState) {
                return {
                    offer: {
                        setLocalDescription: ['stable', 'have-local-offer'],
                        setRemoteDescription: ['stable', 'have-remote-offer']
                    },
                    answer: {
                        setLocalDescription: ['have-remote-offer', 'have-local-pranswer'],
                        setRemoteDescription: ['have-local-offer', 'have-remote-pranswer']
                    }
                }[type][action].indexOf(signalingState) !== -1;
            }

            function maybeAddCandidate(iceTransport, candidate) {
                // Edge's internal representation adds some fields therefore
                // not all fieldѕ are taken into account.
                var alreadyAdded = iceTransport.getRemoteCandidates()
                    .find(function (remoteCandidate) {
                        return candidate.foundation === remoteCandidate.foundation &&
                            candidate.ip === remoteCandidate.ip &&
                            candidate.port === remoteCandidate.port &&
                            candidate.priority === remoteCandidate.priority &&
                            candidate.protocol === remoteCandidate.protocol &&
                            candidate.type === remoteCandidate.type;
                    });
                if (!alreadyAdded) {
                    iceTransport.addRemoteCandidate(candidate);
                }
                return !alreadyAdded;
            }


            function makeError(name, description) {
                var e = new Error(description);
                e.name = name;
                // legacy error codes from https://heycam.github.io/webidl/#idl-DOMException-error-names
                e.code = {
                    NotSupportedError: 9,
                    InvalidStateError: 11,
                    InvalidAccessError: 15,
                    TypeError: undefined,
                    OperationError: undefined
                }[name];
                return e;
            }

            module.exports = function (window, edgeVersion) {
                // https://w3c.github.io/mediacapture-main/#mediastream
                // Helper function to add the track to the stream and
                // dispatch the event ourselves.
                function addTrackToStreamAndFireEvent(track, stream) {
                    stream.addTrack(track);
                    stream.dispatchEvent(new window.MediaStreamTrackEvent('addtrack',
                        {track: track}));
                }

                function removeTrackFromStreamAndFireEvent(track, stream) {
                    stream.removeTrack(track);
                    stream.dispatchEvent(new window.MediaStreamTrackEvent('removetrack',
                        {track: track}));
                }

                function fireAddTrack(pc, track, receiver, streams) {
                    var trackEvent = new Event('track');
                    trackEvent.track = track;
                    trackEvent.receiver = receiver;
                    trackEvent.transceiver = {receiver: receiver};
                    trackEvent.streams = streams;
                    window.setTimeout(function () {
                        pc._dispatchEvent('track', trackEvent);
                    });
                }

                var RTCPeerConnection = function (config) {
                    var pc = this;

                    var _eventTarget = document.createDocumentFragment();
                    ['addEventListener', 'removeEventListener', 'dispatchEvent']
                        .forEach(function (method) {
                            pc[method] = _eventTarget[method].bind(_eventTarget);
                        });

                    this.canTrickleIceCandidates = null;

                    this.needNegotiation = false;

                    this.localStreams = [];
                    this.remoteStreams = [];

                    this._localDescription = null;
                    this._remoteDescription = null;

                    this.signalingState = 'stable';
                    this.iceConnectionState = 'new';
                    this.connectionState = 'new';
                    this.iceGatheringState = 'new';

                    config = JSON.parse(JSON.stringify(config || {}));

                    this.usingBundle = config.bundlePolicy === 'max-bundle';
                    if (config.rtcpMuxPolicy === 'negotiate') {
                        throw(makeError('NotSupportedError',
                            'rtcpMuxPolicy \'negotiate\' is not supported'));
                    } else if (!config.rtcpMuxPolicy) {
                        config.rtcpMuxPolicy = 'require';
                    }

                    switch (config.iceTransportPolicy) {
                        case 'all':
                        case 'relay':
                            break;
                        default:
                            config.iceTransportPolicy = 'all';
                            break;
                    }

                    switch (config.bundlePolicy) {
                        case 'balanced':
                        case 'max-compat':
                        case 'max-bundle':
                            break;
                        default:
                            config.bundlePolicy = 'balanced';
                            break;
                    }

                    config.iceServers = filterIceServers(config.iceServers || [], edgeVersion);

                    this._iceGatherers = [];
                    if (config.iceCandidatePoolSize) {
                        for (var i = config.iceCandidatePoolSize; i > 0; i--) {
                            this._iceGatherers.push(new window.RTCIceGatherer({
                                iceServers: config.iceServers,
                                gatherPolicy: config.iceTransportPolicy
                            }));
                        }
                    } else {
                        config.iceCandidatePoolSize = 0;
                    }

                    this._config = config;

                    // per-track iceGathers, iceTransports, dtlsTransports, rtpSenders, ...
                    // everything that is needed to describe a SDP m-line.
                    this.transceivers = [];

                    this._sdpSessionId = SDPUtils.generateSessionId();
                    this._sdpSessionVersion = 0;

                    this._dtlsRole = undefined; // role for a=setup to use in answers.

                    this._isClosed = false;
                };

                Object.defineProperty(RTCPeerConnection.prototype, 'localDescription', {
                    configurable: true,
                    get: function () {
                        return this._localDescription;
                    }
                });
                Object.defineProperty(RTCPeerConnection.prototype, 'remoteDescription', {
                    configurable: true,
                    get: function () {
                        return this._remoteDescription;
                    }
                });

                // set up event handlers on prototype
                RTCPeerConnection.prototype.onicecandidate = null;
                RTCPeerConnection.prototype.onaddstream = null;
                RTCPeerConnection.prototype.ontrack = null;
                RTCPeerConnection.prototype.onremovestream = null;
                RTCPeerConnection.prototype.onsignalingstatechange = null;
                RTCPeerConnection.prototype.oniceconnectionstatechange = null;
                RTCPeerConnection.prototype.onconnectionstatechange = null;
                RTCPeerConnection.prototype.onicegatheringstatechange = null;
                RTCPeerConnection.prototype.onnegotiationneeded = null;
                RTCPeerConnection.prototype.ondatachannel = null;

                RTCPeerConnection.prototype._dispatchEvent = function (name, event) {
                    if (this._isClosed) {
                        return;
                    }
                    this.dispatchEvent(event);
                    if (typeof this['on' + name] === 'function') {
                        this['on' + name](event);
                    }
                };

                RTCPeerConnection.prototype._emitGatheringStateChange = function () {
                    var event = new Event('icegatheringstatechange');
                    this._dispatchEvent('icegatheringstatechange', event);
                };

                RTCPeerConnection.prototype.getConfiguration = function () {
                    return this._config;
                };

                RTCPeerConnection.prototype.getLocalStreams = function () {
                    return this.localStreams;
                };

                RTCPeerConnection.prototype.getRemoteStreams = function () {
                    return this.remoteStreams;
                };

                // internal helper to create a transceiver object.
                // (which is not yet the same as the WebRTC 1.0 transceiver)
                RTCPeerConnection.prototype._createTransceiver = function (kind, doNotAdd) {
                    var hasBundleTransport = this.transceivers.length > 0;
                    var transceiver = {
                        track: null,
                        iceGatherer: null,
                        iceTransport: null,
                        dtlsTransport: null,
                        localCapabilities: null,
                        remoteCapabilities: null,
                        rtpSender: null,
                        rtpReceiver: null,
                        kind: kind,
                        mid: null,
                        sendEncodingParameters: null,
                        recvEncodingParameters: null,
                        stream: null,
                        associatedRemoteMediaStreams: [],
                        wantReceive: true
                    };
                    if (this.usingBundle && hasBundleTransport) {
                        transceiver.iceTransport = this.transceivers[0].iceTransport;
                        transceiver.dtlsTransport = this.transceivers[0].dtlsTransport;
                    } else {
                        var transports = this._createIceAndDtlsTransports();
                        transceiver.iceTransport = transports.iceTransport;
                        transceiver.dtlsTransport = transports.dtlsTransport;
                    }
                    if (!doNotAdd) {
                        this.transceivers.push(transceiver);
                    }
                    return transceiver;
                };

                RTCPeerConnection.prototype.addTrack = function (track, stream) {
                    if (this._isClosed) {
                        throw makeError('InvalidStateError',
                            'Attempted to call addTrack on a closed peerconnection.');
                    }

                    var alreadyExists = this.transceivers.find(function (s) {
                        return s.track === track;
                    });

                    if (alreadyExists) {
                        throw makeError('InvalidAccessError', 'Track already exists.');
                    }

                    var transceiver;
                    for (var i = 0; i < this.transceivers.length; i++) {
                        if (!this.transceivers[i].track &&
                            this.transceivers[i].kind === track.kind) {
                            transceiver = this.transceivers[i];
                        }
                    }
                    if (!transceiver) {
                        transceiver = this._createTransceiver(track.kind);
                    }

                    this._maybeFireNegotiationNeeded();

                    if (this.localStreams.indexOf(stream) === -1) {
                        this.localStreams.push(stream);
                    }

                    transceiver.track = track;
                    transceiver.stream = stream;
                    transceiver.rtpSender = new window.RTCRtpSender(track,
                        transceiver.dtlsTransport);
                    return transceiver.rtpSender;
                };

                RTCPeerConnection.prototype.addStream = function (stream) {
                    var pc = this;
                    if (edgeVersion >= 15025) {
                        stream.getTracks().forEach(function (track) {
                            pc.addTrack(track, stream);
                        });
                    } else {
                        // Clone is necessary for local demos mostly, attaching directly
                        // to two different senders does not work (build 10547).
                        // Fixed in 15025 (or earlier)
                        var clonedStream = stream.clone();
                        stream.getTracks().forEach(function (track, idx) {
                            var clonedTrack = clonedStream.getTracks()[idx];
                            track.addEventListener('enabled', function (event) {
                                clonedTrack.enabled = event.enabled;
                            });
                        });
                        clonedStream.getTracks().forEach(function (track) {
                            pc.addTrack(track, clonedStream);
                        });
                    }
                };

                RTCPeerConnection.prototype.removeTrack = function (sender) {
                    if (this._isClosed) {
                        throw makeError('InvalidStateError',
                            'Attempted to call removeTrack on a closed peerconnection.');
                    }

                    if (!(sender instanceof window.RTCRtpSender)) {
                        throw new TypeError('Argument 1 of RTCPeerConnection.removeTrack ' +
                            'does not implement interface RTCRtpSender.');
                    }

                    var transceiver = this.transceivers.find(function (t) {
                        return t.rtpSender === sender;
                    });

                    if (!transceiver) {
                        throw makeError('InvalidAccessError',
                            'Sender was not created by this connection.');
                    }
                    var stream = transceiver.stream;

                    transceiver.rtpSender.stop();
                    transceiver.rtpSender = null;
                    transceiver.track = null;
                    transceiver.stream = null;

                    // remove the stream from the set of local streams
                    var localStreams = this.transceivers.map(function (t) {
                        return t.stream;
                    });
                    if (localStreams.indexOf(stream) === -1 &&
                        this.localStreams.indexOf(stream) > -1) {
                        this.localStreams.splice(this.localStreams.indexOf(stream), 1);
                    }

                    this._maybeFireNegotiationNeeded();
                };

                RTCPeerConnection.prototype.removeStream = function (stream) {
                    var pc = this;
                    stream.getTracks().forEach(function (track) {
                        var sender = pc.getSenders().find(function (s) {
                            return s.track === track;
                        });
                        if (sender) {
                            pc.removeTrack(sender);
                        }
                    });
                };

                RTCPeerConnection.prototype.getSenders = function () {
                    return this.transceivers.filter(function (transceiver) {
                        return !!transceiver.rtpSender;
                    })
                        .map(function (transceiver) {
                            return transceiver.rtpSender;
                        });
                };

                RTCPeerConnection.prototype.getReceivers = function () {
                    return this.transceivers.filter(function (transceiver) {
                        return !!transceiver.rtpReceiver;
                    })
                        .map(function (transceiver) {
                            return transceiver.rtpReceiver;
                        });
                };


                RTCPeerConnection.prototype._createIceGatherer = function (sdpMLineIndex,
                                                                           usingBundle) {
                    var pc = this;
                    if (usingBundle && sdpMLineIndex > 0) {
                        return this.transceivers[0].iceGatherer;
                    } else if (this._iceGatherers.length) {
                        return this._iceGatherers.shift();
                    }
                    var iceGatherer = new window.RTCIceGatherer({
                        iceServers: this._config.iceServers,
                        gatherPolicy: this._config.iceTransportPolicy
                    });
                    Object.defineProperty(iceGatherer, 'state',
                        {value: 'new', writable: true}
                    );

                    this.transceivers[sdpMLineIndex].bufferedCandidateEvents = [];
                    this.transceivers[sdpMLineIndex].bufferCandidates = function (event) {
                        var end = !event.candidate || Object.keys(event.candidate).length === 0;
                        // polyfill since RTCIceGatherer.state is not implemented in
                        // Edge 10547 yet.
                        iceGatherer.state = end ? 'completed' : 'gathering';
                        if (pc.transceivers[sdpMLineIndex].bufferedCandidateEvents !== null) {
                            pc.transceivers[sdpMLineIndex].bufferedCandidateEvents.push(event);
                        }
                    };
                    iceGatherer.addEventListener('localcandidate',
                        this.transceivers[sdpMLineIndex].bufferCandidates);
                    return iceGatherer;
                };

                // start gathering from an RTCIceGatherer.
                RTCPeerConnection.prototype._gather = function (mid, sdpMLineIndex) {
                    var pc = this;
                    var iceGatherer = this.transceivers[sdpMLineIndex].iceGatherer;
                    if (iceGatherer.onlocalcandidate) {
                        return;
                    }
                    var bufferedCandidateEvents =
                        this.transceivers[sdpMLineIndex].bufferedCandidateEvents;
                    this.transceivers[sdpMLineIndex].bufferedCandidateEvents = null;
                    iceGatherer.removeEventListener('localcandidate',
                        this.transceivers[sdpMLineIndex].bufferCandidates);
                    iceGatherer.onlocalcandidate = function (evt) {
                        if (pc.usingBundle && sdpMLineIndex > 0) {
                            // if we know that we use bundle we can drop candidates with
                            // ѕdpMLineIndex > 0. If we don't do this then our state gets
                            // confused since we dispose the extra ice gatherer.
                            return;
                        }
                        var event = new Event('icecandidate');
                        event.candidate = {sdpMid: mid, sdpMLineIndex: sdpMLineIndex};

                        var cand = evt.candidate;
                        // Edge emits an empty object for RTCIceCandidateComplete‥
                        var end = !cand || Object.keys(cand).length === 0;
                        if (end) {
                            // polyfill since RTCIceGatherer.state is not implemented in
                            // Edge 10547 yet.
                            if (iceGatherer.state === 'new' || iceGatherer.state === 'gathering') {
                                iceGatherer.state = 'completed';
                            }
                        } else {
                            if (iceGatherer.state === 'new') {
                                iceGatherer.state = 'gathering';
                            }
                            // RTCIceCandidate doesn't have a component, needs to be added
                            cand.component = 1;
                            // also the usernameFragment. TODO: update SDP to take both variants.
                            cand.ufrag = iceGatherer.getLocalParameters().usernameFragment;

                            var serializedCandidate = SDPUtils.writeCandidate(cand);
                            event.candidate = Object.assign(event.candidate,
                                SDPUtils.parseCandidate(serializedCandidate));

                            event.candidate.candidate = serializedCandidate;
                            event.candidate.toJSON = function () {
                                return {
                                    candidate: event.candidate.candidate,
                                    sdpMid: event.candidate.sdpMid,
                                    sdpMLineIndex: event.candidate.sdpMLineIndex,
                                    usernameFragment: event.candidate.usernameFragment
                                };
                            };
                        }

                        // update local description.
                        var sections = SDPUtils.getMediaSections(pc._localDescription.sdp);
                        if (!end) {
                            sections[event.candidate.sdpMLineIndex] +=
                                'a=' + event.candidate.candidate + '\r\n';
                        } else {
                            sections[event.candidate.sdpMLineIndex] +=
                                'a=end-of-candidates\r\n';
                        }
                        pc._localDescription.sdp =
                            SDPUtils.getDescription(pc._localDescription.sdp) +
                            sections.join('');
                        var complete = pc.transceivers.every(function (transceiver) {
                            return transceiver.iceGatherer &&
                                transceiver.iceGatherer.state === 'completed';
                        });

                        if (pc.iceGatheringState !== 'gathering') {
                            pc.iceGatheringState = 'gathering';
                            pc._emitGatheringStateChange();
                        }

                        // Emit candidate. Also emit null candidate when all gatherers are
                        // complete.
                        if (!end) {
                            pc._dispatchEvent('icecandidate', event);
                        }
                        if (complete) {
                            pc._dispatchEvent('icecandidate', new Event('icecandidate'));
                            pc.iceGatheringState = 'complete';
                            pc._emitGatheringStateChange();
                        }
                    };

                    // emit already gathered candidates.
                    window.setTimeout(function () {
                        bufferedCandidateEvents.forEach(function (e) {
                            iceGatherer.onlocalcandidate(e);
                        });
                    }, 0);
                };

                // Create ICE transport and DTLS transport.
                RTCPeerConnection.prototype._createIceAndDtlsTransports = function () {
                    var pc = this;
                    var iceTransport = new window.RTCIceTransport(null);
                    iceTransport.onicestatechange = function () {
                        pc._updateIceConnectionState();
                        pc._updateConnectionState();
                    };

                    var dtlsTransport = new window.RTCDtlsTransport(iceTransport);
                    dtlsTransport.ondtlsstatechange = function () {
                        pc._updateConnectionState();
                    };
                    dtlsTransport.onerror = function () {
                        // onerror does not set state to failed by itself.
                        Object.defineProperty(dtlsTransport, 'state',
                            {value: 'failed', writable: true});
                        pc._updateConnectionState();
                    };

                    return {
                        iceTransport: iceTransport,
                        dtlsTransport: dtlsTransport
                    };
                };

                // Destroy ICE gatherer, ICE transport and DTLS transport.
                // Without triggering the callbacks.
                RTCPeerConnection.prototype._disposeIceAndDtlsTransports = function (
                    sdpMLineIndex) {
                    var iceGatherer = this.transceivers[sdpMLineIndex].iceGatherer;
                    if (iceGatherer) {
                        delete iceGatherer.onlocalcandidate;
                        delete this.transceivers[sdpMLineIndex].iceGatherer;
                    }
                    var iceTransport = this.transceivers[sdpMLineIndex].iceTransport;
                    if (iceTransport) {
                        delete iceTransport.onicestatechange;
                        delete this.transceivers[sdpMLineIndex].iceTransport;
                    }
                    var dtlsTransport = this.transceivers[sdpMLineIndex].dtlsTransport;
                    if (dtlsTransport) {
                        delete dtlsTransport.ondtlsstatechange;
                        delete dtlsTransport.onerror;
                        delete this.transceivers[sdpMLineIndex].dtlsTransport;
                    }
                };

                // Start the RTP Sender and Receiver for a transceiver.
                RTCPeerConnection.prototype._transceive = function (transceiver,
                                                                    send, recv) {
                    var params = getCommonCapabilities(transceiver.localCapabilities,
                        transceiver.remoteCapabilities);
                    if (send && transceiver.rtpSender) {
                        params.encodings = transceiver.sendEncodingParameters;
                        params.rtcp = {
                            cname: SDPUtils.localCName,
                            compound: transceiver.rtcpParameters.compound
                        };
                        if (transceiver.recvEncodingParameters.length) {
                            params.rtcp.ssrc = transceiver.recvEncodingParameters[0].ssrc;
                        }
                        transceiver.rtpSender.send(params);
                    }
                    if (recv && transceiver.rtpReceiver && params.codecs.length > 0) {
                        // remove RTX field in Edge 14942
                        if (transceiver.kind === 'video'
                            && transceiver.recvEncodingParameters
                            && edgeVersion < 15019) {
                            transceiver.recvEncodingParameters.forEach(function (p) {
                                delete p.rtx;
                            });
                        }
                        if (transceiver.recvEncodingParameters.length) {
                            params.encodings = transceiver.recvEncodingParameters;
                        } else {
                            params.encodings = [{}];
                        }
                        params.rtcp = {
                            compound: transceiver.rtcpParameters.compound
                        };
                        if (transceiver.rtcpParameters.cname) {
                            params.rtcp.cname = transceiver.rtcpParameters.cname;
                        }
                        if (transceiver.sendEncodingParameters.length) {
                            params.rtcp.ssrc = transceiver.sendEncodingParameters[0].ssrc;
                        }
                        transceiver.rtpReceiver.receive(params);
                    }
                };

                RTCPeerConnection.prototype.setLocalDescription = function (description) {
                    var pc = this;

                    // Note: pranswer is not supported.
                    if (['offer', 'answer'].indexOf(description.type) === -1) {
                        return Promise.reject(makeError('TypeError',
                            'Unsupported type "' + description.type + '"'));
                    }

                    if (!isActionAllowedInSignalingState('setLocalDescription',
                        description.type, pc.signalingState) || pc._isClosed) {
                        return Promise.reject(makeError('InvalidStateError',
                            'Can not set local ' + description.type +
                            ' in state ' + pc.signalingState));
                    }

                    var sections;
                    var sessionpart;
                    if (description.type === 'offer') {
                        // VERY limited support for SDP munging. Limited to:
                        // * changing the order of codecs
                        sections = SDPUtils.splitSections(description.sdp);
                        sessionpart = sections.shift();
                        sections.forEach(function (mediaSection, sdpMLineIndex) {
                            var caps = SDPUtils.parseRtpParameters(mediaSection);
                            pc.transceivers[sdpMLineIndex].localCapabilities = caps;
                        });

                        pc.transceivers.forEach(function (transceiver, sdpMLineIndex) {
                            pc._gather(transceiver.mid, sdpMLineIndex);
                        });
                    } else if (description.type === 'answer') {
                        sections = SDPUtils.splitSections(pc._remoteDescription.sdp);
                        sessionpart = sections.shift();
                        var isIceLite = SDPUtils.matchPrefix(sessionpart,
                            'a=ice-lite').length > 0;
                        sections.forEach(function (mediaSection, sdpMLineIndex) {
                            var transceiver = pc.transceivers[sdpMLineIndex];
                            var iceGatherer = transceiver.iceGatherer;
                            var iceTransport = transceiver.iceTransport;
                            var dtlsTransport = transceiver.dtlsTransport;
                            var localCapabilities = transceiver.localCapabilities;
                            var remoteCapabilities = transceiver.remoteCapabilities;

                            // treat bundle-only as not-rejected.
                            var rejected = SDPUtils.isRejected(mediaSection) &&
                                SDPUtils.matchPrefix(mediaSection, 'a=bundle-only').length === 0;

                            if (!rejected && !transceiver.rejected) {
                                var remoteIceParameters = SDPUtils.getIceParameters(
                                    mediaSection, sessionpart);
                                var remoteDtlsParameters = SDPUtils.getDtlsParameters(
                                    mediaSection, sessionpart);
                                if (isIceLite) {
                                    remoteDtlsParameters.role = 'server';
                                }

                                if (!pc.usingBundle || sdpMLineIndex === 0) {
                                    pc._gather(transceiver.mid, sdpMLineIndex);
                                    if (iceTransport.state === 'new') {
                                        iceTransport.start(iceGatherer, remoteIceParameters,
                                            isIceLite ? 'controlling' : 'controlled');
                                    }
                                    if (dtlsTransport.state === 'new') {
                                        dtlsTransport.start(remoteDtlsParameters);
                                    }
                                }

                                // Calculate intersection of capabilities.
                                var params = getCommonCapabilities(localCapabilities,
                                    remoteCapabilities);

                                // Start the RTCRtpSender. The RTCRtpReceiver for this
                                // transceiver has already been started in setRemoteDescription.
                                pc._transceive(transceiver,
                                    params.codecs.length > 0,
                                    false);
                            }
                        });
                    }

                    pc._localDescription = {
                        type: description.type,
                        sdp: description.sdp
                    };
                    if (description.type === 'offer') {
                        pc._updateSignalingState('have-local-offer');
                    } else {
                        pc._updateSignalingState('stable');
                    }

                    return Promise.resolve();
                };

                RTCPeerConnection.prototype.setRemoteDescription = function (description) {
                    var pc = this;

                    // Note: pranswer is not supported.
                    if (['offer', 'answer'].indexOf(description.type) === -1) {
                        return Promise.reject(makeError('TypeError',
                            'Unsupported type "' + description.type + '"'));
                    }

                    if (!isActionAllowedInSignalingState('setRemoteDescription',
                        description.type, pc.signalingState) || pc._isClosed) {
                        return Promise.reject(makeError('InvalidStateError',
                            'Can not set remote ' + description.type +
                            ' in state ' + pc.signalingState));
                    }

                    var streams = {};
                    pc.remoteStreams.forEach(function (stream) {
                        streams[stream.id] = stream;
                    });
                    var receiverList = [];
                    var sections = SDPUtils.splitSections(description.sdp);
                    var sessionpart = sections.shift();
                    var isIceLite = SDPUtils.matchPrefix(sessionpart,
                        'a=ice-lite').length > 0;
                    var usingBundle = SDPUtils.matchPrefix(sessionpart,
                        'a=group:BUNDLE ').length > 0;
                    pc.usingBundle = usingBundle;
                    var iceOptions = SDPUtils.matchPrefix(sessionpart,
                        'a=ice-options:')[0];
                    if (iceOptions) {
                        pc.canTrickleIceCandidates = iceOptions.substr(14).split(' ')
                            .indexOf('trickle') >= 0;
                    } else {
                        pc.canTrickleIceCandidates = false;
                    }

                    sections.forEach(function (mediaSection, sdpMLineIndex) {
                        var lines = SDPUtils.splitLines(mediaSection);
                        var kind = SDPUtils.getKind(mediaSection);
                        // treat bundle-only as not-rejected.
                        var rejected = SDPUtils.isRejected(mediaSection) &&
                            SDPUtils.matchPrefix(mediaSection, 'a=bundle-only').length === 0;
                        var protocol = lines[0].substr(2).split(' ')[2];

                        var direction = SDPUtils.getDirection(mediaSection, sessionpart);
                        var remoteMsid = SDPUtils.parseMsid(mediaSection);

                        var mid = SDPUtils.getMid(mediaSection) || SDPUtils.generateIdentifier();

                        // Reject datachannels which are not implemented yet.
                        if (rejected || (kind === 'application' && (protocol === 'DTLS/SCTP' ||
                            protocol === 'UDP/DTLS/SCTP'))) {
                            // TODO: this is dangerous in the case where a non-rejected m-line
                            //     becomes rejected.
                            pc.transceivers[sdpMLineIndex] = {
                                mid: mid,
                                kind: kind,
                                protocol: protocol,
                                rejected: true
                            };
                            return;
                        }

                        if (!rejected && pc.transceivers[sdpMLineIndex] &&
                            pc.transceivers[sdpMLineIndex].rejected) {
                            // recycle a rejected transceiver.
                            pc.transceivers[sdpMLineIndex] = pc._createTransceiver(kind, true);
                        }

                        var transceiver;
                        var iceGatherer;
                        var iceTransport;
                        var dtlsTransport;
                        var rtpReceiver;
                        var sendEncodingParameters;
                        var recvEncodingParameters;
                        var localCapabilities;

                        var track;
                        // FIXME: ensure the mediaSection has rtcp-mux set.
                        var remoteCapabilities = SDPUtils.parseRtpParameters(mediaSection);
                        var remoteIceParameters;
                        var remoteDtlsParameters;
                        if (!rejected) {
                            remoteIceParameters = SDPUtils.getIceParameters(mediaSection,
                                sessionpart);
                            remoteDtlsParameters = SDPUtils.getDtlsParameters(mediaSection,
                                sessionpart);
                            remoteDtlsParameters.role = 'client';
                        }
                        recvEncodingParameters =
                            SDPUtils.parseRtpEncodingParameters(mediaSection);

                        var rtcpParameters = SDPUtils.parseRtcpParameters(mediaSection);

                        var isComplete = SDPUtils.matchPrefix(mediaSection,
                            'a=end-of-candidates', sessionpart).length > 0;
                        var cands = SDPUtils.matchPrefix(mediaSection, 'a=candidate:')
                            .map(function (cand) {
                                return SDPUtils.parseCandidate(cand);
                            })
                            .filter(function (cand) {
                                return cand.component === 1;
                            });

                        // Check if we can use BUNDLE and dispose transports.
                        if ((description.type === 'offer' || description.type === 'answer') &&
                            !rejected && usingBundle && sdpMLineIndex > 0 &&
                            pc.transceivers[sdpMLineIndex]) {
                            pc._disposeIceAndDtlsTransports(sdpMLineIndex);
                            pc.transceivers[sdpMLineIndex].iceGatherer =
                                pc.transceivers[0].iceGatherer;
                            pc.transceivers[sdpMLineIndex].iceTransport =
                                pc.transceivers[0].iceTransport;
                            pc.transceivers[sdpMLineIndex].dtlsTransport =
                                pc.transceivers[0].dtlsTransport;
                            if (pc.transceivers[sdpMLineIndex].rtpSender) {
                                pc.transceivers[sdpMLineIndex].rtpSender.setTransport(
                                    pc.transceivers[0].dtlsTransport);
                            }
                            if (pc.transceivers[sdpMLineIndex].rtpReceiver) {
                                pc.transceivers[sdpMLineIndex].rtpReceiver.setTransport(
                                    pc.transceivers[0].dtlsTransport);
                            }
                        }
                        if (description.type === 'offer' && !rejected) {
                            transceiver = pc.transceivers[sdpMLineIndex] ||
                                pc._createTransceiver(kind);
                            transceiver.mid = mid;

                            if (!transceiver.iceGatherer) {
                                transceiver.iceGatherer = pc._createIceGatherer(sdpMLineIndex,
                                    usingBundle);
                            }

                            if (cands.length && transceiver.iceTransport.state === 'new') {
                                if (isComplete && (!usingBundle || sdpMLineIndex === 0)) {
                                    transceiver.iceTransport.setRemoteCandidates(cands);
                                } else {
                                    cands.forEach(function (candidate) {
                                        maybeAddCandidate(transceiver.iceTransport, candidate);
                                    });
                                }
                            }

                            localCapabilities = window.RTCRtpReceiver.getCapabilities(kind);

                            // filter RTX until additional stuff needed for RTX is implemented
                            // in adapter.js
                            if (edgeVersion < 15019) {
                                localCapabilities.codecs = localCapabilities.codecs.filter(
                                    function (codec) {
                                        return codec.name !== 'rtx';
                                    });
                            }

                            sendEncodingParameters = transceiver.sendEncodingParameters || [{
                                ssrc: (2 * sdpMLineIndex + 2) * 1001
                            }];

                            // TODO: rewrite to use http://w3c.github.io/webrtc-pc/#set-associated-remote-streams
                            var isNewTrack = false;
                            if (direction === 'sendrecv' || direction === 'sendonly') {
                                isNewTrack = !transceiver.rtpReceiver;
                                rtpReceiver = transceiver.rtpReceiver ||
                                    new window.RTCRtpReceiver(transceiver.dtlsTransport, kind);

                                if (isNewTrack) {
                                    var stream;
                                    track = rtpReceiver.track;
                                    // FIXME: does not work with Plan B.
                                    if (remoteMsid && remoteMsid.stream === '-') {
                                        // no-op. a stream id of '-' means: no associated stream.
                                    } else if (remoteMsid) {
                                        if (!streams[remoteMsid.stream]) {
                                            streams[remoteMsid.stream] = new window.MediaStream();
                                            Object.defineProperty(streams[remoteMsid.stream], 'id', {
                                                get: function () {
                                                    return remoteMsid.stream;
                                                }
                                            });
                                        }
                                        Object.defineProperty(track, 'id', {
                                            get: function () {
                                                return remoteMsid.track;
                                            }
                                        });
                                        stream = streams[remoteMsid.stream];
                                    } else {
                                        if (!streams.default) {
                                            streams.default = new window.MediaStream();
                                        }
                                        stream = streams.default;
                                    }
                                    if (stream) {
                                        addTrackToStreamAndFireEvent(track, stream);
                                        transceiver.associatedRemoteMediaStreams.push(stream);
                                    }
                                    receiverList.push([track, rtpReceiver, stream]);
                                }
                            } else if (transceiver.rtpReceiver && transceiver.rtpReceiver.track) {
                                transceiver.associatedRemoteMediaStreams.forEach(function (s) {
                                    var nativeTrack = s.getTracks().find(function (t) {
                                        return t.id === transceiver.rtpReceiver.track.id;
                                    });
                                    if (nativeTrack) {
                                        removeTrackFromStreamAndFireEvent(nativeTrack, s);
                                    }
                                });
                                transceiver.associatedRemoteMediaStreams = [];
                            }

                            transceiver.localCapabilities = localCapabilities;
                            transceiver.remoteCapabilities = remoteCapabilities;
                            transceiver.rtpReceiver = rtpReceiver;
                            transceiver.rtcpParameters = rtcpParameters;
                            transceiver.sendEncodingParameters = sendEncodingParameters;
                            transceiver.recvEncodingParameters = recvEncodingParameters;

                            // Start the RTCRtpReceiver now. The RTPSender is started in
                            // setLocalDescription.
                            pc._transceive(pc.transceivers[sdpMLineIndex],
                                false,
                                isNewTrack);
                        } else if (description.type === 'answer' && !rejected) {
                            transceiver = pc.transceivers[sdpMLineIndex];
                            iceGatherer = transceiver.iceGatherer;
                            iceTransport = transceiver.iceTransport;
                            dtlsTransport = transceiver.dtlsTransport;
                            rtpReceiver = transceiver.rtpReceiver;
                            sendEncodingParameters = transceiver.sendEncodingParameters;
                            localCapabilities = transceiver.localCapabilities;

                            pc.transceivers[sdpMLineIndex].recvEncodingParameters =
                                recvEncodingParameters;
                            pc.transceivers[sdpMLineIndex].remoteCapabilities =
                                remoteCapabilities;
                            pc.transceivers[sdpMLineIndex].rtcpParameters = rtcpParameters;

                            if (cands.length && iceTransport.state === 'new') {
                                if ((isIceLite || isComplete) &&
                                    (!usingBundle || sdpMLineIndex === 0)) {
                                    iceTransport.setRemoteCandidates(cands);
                                } else {
                                    cands.forEach(function (candidate) {
                                        maybeAddCandidate(transceiver.iceTransport, candidate);
                                    });
                                }
                            }

                            if (!usingBundle || sdpMLineIndex === 0) {
                                if (iceTransport.state === 'new') {
                                    iceTransport.start(iceGatherer, remoteIceParameters,
                                        'controlling');
                                }
                                if (dtlsTransport.state === 'new') {
                                    dtlsTransport.start(remoteDtlsParameters);
                                }
                            }

                            // If the offer contained RTX but the answer did not,
                            // remove RTX from sendEncodingParameters.
                            var commonCapabilities = getCommonCapabilities(
                                transceiver.localCapabilities,
                                transceiver.remoteCapabilities);

                            var hasRtx = commonCapabilities.codecs.filter(function (c) {
                                return c.name.toLowerCase() === 'rtx';
                            }).length;
                            if (!hasRtx && transceiver.sendEncodingParameters[0].rtx) {
                                delete transceiver.sendEncodingParameters[0].rtx;
                            }

                            pc._transceive(transceiver,
                                direction === 'sendrecv' || direction === 'recvonly',
                                direction === 'sendrecv' || direction === 'sendonly');

                            // TODO: rewrite to use http://w3c.github.io/webrtc-pc/#set-associated-remote-streams
                            if (rtpReceiver &&
                                (direction === 'sendrecv' || direction === 'sendonly')) {
                                track = rtpReceiver.track;
                                if (remoteMsid) {
                                    if (!streams[remoteMsid.stream]) {
                                        streams[remoteMsid.stream] = new window.MediaStream();
                                    }
                                    addTrackToStreamAndFireEvent(track, streams[remoteMsid.stream]);
                                    receiverList.push([track, rtpReceiver, streams[remoteMsid.stream]]);
                                } else {
                                    if (!streams.default) {
                                        streams.default = new window.MediaStream();
                                    }
                                    addTrackToStreamAndFireEvent(track, streams.default);
                                    receiverList.push([track, rtpReceiver, streams.default]);
                                }
                            } else {
                                // FIXME: actually the receiver should be created later.
                                delete transceiver.rtpReceiver;
                            }
                        }
                    });

                    if (pc._dtlsRole === undefined) {
                        pc._dtlsRole = description.type === 'offer' ? 'active' : 'passive';
                    }

                    pc._remoteDescription = {
                        type: description.type,
                        sdp: description.sdp
                    };
                    if (description.type === 'offer') {
                        pc._updateSignalingState('have-remote-offer');
                    } else {
                        pc._updateSignalingState('stable');
                    }
                    Object.keys(streams).forEach(function (sid) {
                        var stream = streams[sid];
                        if (stream.getTracks().length) {
                            if (pc.remoteStreams.indexOf(stream) === -1) {
                                pc.remoteStreams.push(stream);
                                var event = new Event('addstream');
                                event.stream = stream;
                                window.setTimeout(function () {
                                    pc._dispatchEvent('addstream', event);
                                });
                            }

                            receiverList.forEach(function (item) {
                                var track = item[0];
                                var receiver = item[1];
                                if (stream.id !== item[2].id) {
                                    return;
                                }
                                fireAddTrack(pc, track, receiver, [stream]);
                            });
                        }
                    });
                    receiverList.forEach(function (item) {
                        if (item[2]) {
                            return;
                        }
                        fireAddTrack(pc, item[0], item[1], []);
                    });

                    // check whether addIceCandidate({}) was called within four seconds after
                    // setRemoteDescription.
                    window.setTimeout(function () {
                        if (!(pc && pc.transceivers)) {
                            return;
                        }
                        pc.transceivers.forEach(function (transceiver) {
                            if (transceiver.iceTransport &&
                                transceiver.iceTransport.state === 'new' &&
                                transceiver.iceTransport.getRemoteCandidates().length > 0) {
                                console.warn('Timeout for addRemoteCandidate. Consider sending ' +
                                    'an end-of-candidates notification');
                                transceiver.iceTransport.addRemoteCandidate({});
                            }
                        });
                    }, 4000);

                    return Promise.resolve();
                };

                RTCPeerConnection.prototype.close = function () {
                    this.transceivers.forEach(function (transceiver) {
                        /* not yet
        if (transceiver.iceGatherer) {
          transceiver.iceGatherer.close();
        }
        */
                        if (transceiver.iceTransport) {
                            transceiver.iceTransport.stop();
                        }
                        if (transceiver.dtlsTransport) {
                            transceiver.dtlsTransport.stop();
                        }
                        if (transceiver.rtpSender) {
                            transceiver.rtpSender.stop();
                        }
                        if (transceiver.rtpReceiver) {
                            transceiver.rtpReceiver.stop();
                        }
                    });
                    // FIXME: clean up tracks, local streams, remote streams, etc
                    this._isClosed = true;
                    this._updateSignalingState('closed');
                };

                // Update the signaling state.
                RTCPeerConnection.prototype._updateSignalingState = function (newState) {
                    this.signalingState = newState;
                    var event = new Event('signalingstatechange');
                    this._dispatchEvent('signalingstatechange', event);
                };

                // Determine whether to fire the negotiationneeded event.
                RTCPeerConnection.prototype._maybeFireNegotiationNeeded = function () {
                    var pc = this;
                    if (this.signalingState !== 'stable' || this.needNegotiation === true) {
                        return;
                    }
                    this.needNegotiation = true;
                    window.setTimeout(function () {
                        if (pc.needNegotiation) {
                            pc.needNegotiation = false;
                            var event = new Event('negotiationneeded');
                            pc._dispatchEvent('negotiationneeded', event);
                        }
                    }, 0);
                };

                // Update the ice connection state.
                RTCPeerConnection.prototype._updateIceConnectionState = function () {
                    var newState;
                    var states = {
                        'new': 0,
                        closed: 0,
                        checking: 0,
                        connected: 0,
                        completed: 0,
                        disconnected: 0,
                        failed: 0
                    };
                    this.transceivers.forEach(function (transceiver) {
                        if (transceiver.iceTransport && !transceiver.rejected) {
                            states[transceiver.iceTransport.state]++;
                        }
                    });

                    newState = 'new';
                    if (states.failed > 0) {
                        newState = 'failed';
                    } else if (states.checking > 0) {
                        newState = 'checking';
                    } else if (states.disconnected > 0) {
                        newState = 'disconnected';
                    } else if (states.new > 0) {
                        newState = 'new';
                    } else if (states.connected > 0) {
                        newState = 'connected';
                    } else if (states.completed > 0) {
                        newState = 'completed';
                    }

                    if (newState !== this.iceConnectionState) {
                        this.iceConnectionState = newState;
                        var event = new Event('iceconnectionstatechange');
                        this._dispatchEvent('iceconnectionstatechange', event);
                    }
                };

                // Update the connection state.
                RTCPeerConnection.prototype._updateConnectionState = function () {
                    var newState;
                    var states = {
                        'new': 0,
                        closed: 0,
                        connecting: 0,
                        connected: 0,
                        completed: 0,
                        disconnected: 0,
                        failed: 0
                    };
                    this.transceivers.forEach(function (transceiver) {
                        if (transceiver.iceTransport && transceiver.dtlsTransport &&
                            !transceiver.rejected) {
                            states[transceiver.iceTransport.state]++;
                            states[transceiver.dtlsTransport.state]++;
                        }
                    });
                    // ICETransport.completed and connected are the same for this purpose.
                    states.connected += states.completed;

                    newState = 'new';
                    if (states.failed > 0) {
                        newState = 'failed';
                    } else if (states.connecting > 0) {
                        newState = 'connecting';
                    } else if (states.disconnected > 0) {
                        newState = 'disconnected';
                    } else if (states.new > 0) {
                        newState = 'new';
                    } else if (states.connected > 0) {
                        newState = 'connected';
                    }

                    if (newState !== this.connectionState) {
                        this.connectionState = newState;
                        var event = new Event('connectionstatechange');
                        this._dispatchEvent('connectionstatechange', event);
                    }
                };

                RTCPeerConnection.prototype.createOffer = function () {
                    var pc = this;

                    if (pc._isClosed) {
                        return Promise.reject(makeError('InvalidStateError',
                            'Can not call createOffer after close'));
                    }

                    var numAudioTracks = pc.transceivers.filter(function (t) {
                        return t.kind === 'audio';
                    }).length;
                    var numVideoTracks = pc.transceivers.filter(function (t) {
                        return t.kind === 'video';
                    }).length;

                    // Determine number of audio and video tracks we need to send/recv.
                    var offerOptions = arguments[0];
                    if (offerOptions) {
                        // Reject Chrome legacy constraints.
                        if (offerOptions.mandatory || offerOptions.optional) {
                            throw new TypeError(
                                'Legacy mandatory/optional constraints not supported.');
                        }
                        if (offerOptions.offerToReceiveAudio !== undefined) {
                            if (offerOptions.offerToReceiveAudio === true) {
                                numAudioTracks = 1;
                            } else if (offerOptions.offerToReceiveAudio === false) {
                                numAudioTracks = 0;
                            } else {
                                numAudioTracks = offerOptions.offerToReceiveAudio;
                            }
                        }
                        if (offerOptions.offerToReceiveVideo !== undefined) {
                            if (offerOptions.offerToReceiveVideo === true) {
                                numVideoTracks = 1;
                            } else if (offerOptions.offerToReceiveVideo === false) {
                                numVideoTracks = 0;
                            } else {
                                numVideoTracks = offerOptions.offerToReceiveVideo;
                            }
                        }
                    }

                    pc.transceivers.forEach(function (transceiver) {
                        if (transceiver.kind === 'audio') {
                            numAudioTracks--;
                            if (numAudioTracks < 0) {
                                transceiver.wantReceive = false;
                            }
                        } else if (transceiver.kind === 'video') {
                            numVideoTracks--;
                            if (numVideoTracks < 0) {
                                transceiver.wantReceive = false;
                            }
                        }
                    });

                    // Create M-lines for recvonly streams.
                    while (numAudioTracks > 0 || numVideoTracks > 0) {
                        if (numAudioTracks > 0) {
                            pc._createTransceiver('audio');
                            numAudioTracks--;
                        }
                        if (numVideoTracks > 0) {
                            pc._createTransceiver('video');
                            numVideoTracks--;
                        }
                    }

                    var sdp = SDPUtils.writeSessionBoilerplate(pc._sdpSessionId,
                        pc._sdpSessionVersion++);
                    pc.transceivers.forEach(function (transceiver, sdpMLineIndex) {
                        // For each track, create an ice gatherer, ice transport,
                        // dtls transport, potentially rtpsender and rtpreceiver.
                        var track = transceiver.track;
                        var kind = transceiver.kind;
                        var mid = transceiver.mid || SDPUtils.generateIdentifier();
                        transceiver.mid = mid;

                        if (!transceiver.iceGatherer) {
                            transceiver.iceGatherer = pc._createIceGatherer(sdpMLineIndex,
                                pc.usingBundle);
                        }

                        var localCapabilities = window.RTCRtpSender.getCapabilities(kind);
                        // filter RTX until additional stuff needed for RTX is implemented
                        // in adapter.js
                        if (edgeVersion < 15019) {
                            localCapabilities.codecs = localCapabilities.codecs.filter(
                                function (codec) {
                                    return codec.name !== 'rtx';
                                });
                        }
                        localCapabilities.codecs.forEach(function (codec) {
                            // work around https://bugs.chromium.org/p/webrtc/issues/detail?id=6552
                            // by adding level-asymmetry-allowed=1
                            if (codec.name === 'H264' &&
                                codec.parameters['level-asymmetry-allowed'] === undefined) {
                                codec.parameters['level-asymmetry-allowed'] = '1';
                            }

                            // for subsequent offers, we might have to re-use the payload
                            // type of the last offer.
                            if (transceiver.remoteCapabilities &&
                                transceiver.remoteCapabilities.codecs) {
                                transceiver.remoteCapabilities.codecs.forEach(function (remoteCodec) {
                                    if (codec.name.toLowerCase() === remoteCodec.name.toLowerCase() &&
                                        codec.clockRate === remoteCodec.clockRate) {
                                        codec.preferredPayloadType = remoteCodec.payloadType;
                                    }
                                });
                            }
                        });
                        localCapabilities.headerExtensions.forEach(function (hdrExt) {
                            var remoteExtensions = transceiver.remoteCapabilities &&
                                transceiver.remoteCapabilities.headerExtensions || [];
                            remoteExtensions.forEach(function (rHdrExt) {
                                if (hdrExt.uri === rHdrExt.uri) {
                                    hdrExt.id = rHdrExt.id;
                                }
                            });
                        });

                        // generate an ssrc now, to be used later in rtpSender.send
                        var sendEncodingParameters = transceiver.sendEncodingParameters || [{
                            ssrc: (2 * sdpMLineIndex + 1) * 1001
                        }];
                        if (track) {
                            // add RTX
                            if (edgeVersion >= 15019 && kind === 'video' &&
                                !sendEncodingParameters[0].rtx) {
                                sendEncodingParameters[0].rtx = {
                                    ssrc: sendEncodingParameters[0].ssrc + 1
                                };
                            }
                        }

                        if (transceiver.wantReceive) {
                            transceiver.rtpReceiver = new window.RTCRtpReceiver(
                                transceiver.dtlsTransport, kind);
                        }

                        transceiver.localCapabilities = localCapabilities;
                        transceiver.sendEncodingParameters = sendEncodingParameters;
                    });

                    // always offer BUNDLE and dispose on return if not supported.
                    if (pc._config.bundlePolicy !== 'max-compat') {
                        sdp += 'a=group:BUNDLE ' + pc.transceivers.map(function (t) {
                            return t.mid;
                        }).join(' ') + '\r\n';
                    }
                    sdp += 'a=ice-options:trickle\r\n';

                    pc.transceivers.forEach(function (transceiver, sdpMLineIndex) {
                        sdp += writeMediaSection(transceiver, transceiver.localCapabilities,
                            'offer', transceiver.stream, pc._dtlsRole);
                        sdp += 'a=rtcp-rsize\r\n';

                        if (transceiver.iceGatherer && pc.iceGatheringState !== 'new' &&
                            (sdpMLineIndex === 0 || !pc.usingBundle)) {
                            transceiver.iceGatherer.getLocalCandidates().forEach(function (cand) {
                                cand.component = 1;
                                sdp += 'a=' + SDPUtils.writeCandidate(cand) + '\r\n';
                            });

                            if (transceiver.iceGatherer.state === 'completed') {
                                sdp += 'a=end-of-candidates\r\n';
                            }
                        }
                    });

                    var desc = new window.RTCSessionDescription({
                        type: 'offer',
                        sdp: sdp
                    });
                    return Promise.resolve(desc);
                };

                RTCPeerConnection.prototype.createAnswer = function () {
                    var pc = this;

                    if (pc._isClosed) {
                        return Promise.reject(makeError('InvalidStateError',
                            'Can not call createAnswer after close'));
                    }

                    if (!(pc.signalingState === 'have-remote-offer' ||
                        pc.signalingState === 'have-local-pranswer')) {
                        return Promise.reject(makeError('InvalidStateError',
                            'Can not call createAnswer in signalingState ' + pc.signalingState));
                    }

                    var sdp = SDPUtils.writeSessionBoilerplate(pc._sdpSessionId,
                        pc._sdpSessionVersion++);
                    if (pc.usingBundle) {
                        sdp += 'a=group:BUNDLE ' + pc.transceivers.map(function (t) {
                            return t.mid;
                        }).join(' ') + '\r\n';
                    }
                    sdp += 'a=ice-options:trickle\r\n';

                    var mediaSectionsInOffer = SDPUtils.getMediaSections(
                        pc._remoteDescription.sdp).length;
                    pc.transceivers.forEach(function (transceiver, sdpMLineIndex) {
                        if (sdpMLineIndex + 1 > mediaSectionsInOffer) {
                            return;
                        }
                        if (transceiver.rejected) {
                            if (transceiver.kind === 'application') {
                                if (transceiver.protocol === 'DTLS/SCTP') { // legacy fmt
                                    sdp += 'm=application 0 DTLS/SCTP 5000\r\n';
                                } else {
                                    sdp += 'm=application 0 ' + transceiver.protocol +
                                        ' webrtc-datachannel\r\n';
                                }
                            } else if (transceiver.kind === 'audio') {
                                sdp += 'm=audio 0 UDP/TLS/RTP/SAVPF 0\r\n' +
                                    'a=rtpmap:0 PCMU/8000\r\n';
                            } else if (transceiver.kind === 'video') {
                                sdp += 'm=video 0 UDP/TLS/RTP/SAVPF 120\r\n' +
                                    'a=rtpmap:120 VP8/90000\r\n';
                            }
                            sdp += 'c=IN IP4 0.0.0.0\r\n' +
                                'a=inactive\r\n' +
                                'a=mid:' + transceiver.mid + '\r\n';
                            return;
                        }

                        // FIXME: look at direction.
                        if (transceiver.stream) {
                            var localTrack;
                            if (transceiver.kind === 'audio') {
                                localTrack = transceiver.stream.getAudioTracks()[0];
                            } else if (transceiver.kind === 'video') {
                                localTrack = transceiver.stream.getVideoTracks()[0];
                            }
                            if (localTrack) {
                                // add RTX
                                if (edgeVersion >= 15019 && transceiver.kind === 'video' &&
                                    !transceiver.sendEncodingParameters[0].rtx) {
                                    transceiver.sendEncodingParameters[0].rtx = {
                                        ssrc: transceiver.sendEncodingParameters[0].ssrc + 1
                                    };
                                }
                            }
                        }

                        // Calculate intersection of capabilities.
                        var commonCapabilities = getCommonCapabilities(
                            transceiver.localCapabilities,
                            transceiver.remoteCapabilities);

                        var hasRtx = commonCapabilities.codecs.filter(function (c) {
                            return c.name.toLowerCase() === 'rtx';
                        }).length;
                        if (!hasRtx && transceiver.sendEncodingParameters[0].rtx) {
                            delete transceiver.sendEncodingParameters[0].rtx;
                        }

                        sdp += writeMediaSection(transceiver, commonCapabilities,
                            'answer', transceiver.stream, pc._dtlsRole);
                        if (transceiver.rtcpParameters &&
                            transceiver.rtcpParameters.reducedSize) {
                            sdp += 'a=rtcp-rsize\r\n';
                        }
                    });

                    var desc = new window.RTCSessionDescription({
                        type: 'answer',
                        sdp: sdp
                    });
                    return Promise.resolve(desc);
                };

                RTCPeerConnection.prototype.addIceCandidate = function (candidate) {
                    var pc = this;
                    var sections;
                    if (candidate && !(candidate.sdpMLineIndex !== undefined ||
                        candidate.sdpMid)) {
                        return Promise.reject(new TypeError('sdpMLineIndex or sdpMid required'));
                    }

                    // TODO: needs to go into ops queue.
                    return new Promise(function (resolve, reject) {
                        if (!pc._remoteDescription) {
                            return reject(makeError('InvalidStateError',
                                'Can not add ICE candidate without a remote description'));
                        } else if (!candidate || candidate.candidate === '') {
                            for (var j = 0; j < pc.transceivers.length; j++) {
                                if (pc.transceivers[j].rejected) {
                                    continue;
                                }
                                pc.transceivers[j].iceTransport.addRemoteCandidate({});
                                sections = SDPUtils.getMediaSections(pc._remoteDescription.sdp);
                                sections[j] += 'a=end-of-candidates\r\n';
                                pc._remoteDescription.sdp =
                                    SDPUtils.getDescription(pc._remoteDescription.sdp) +
                                    sections.join('');
                                if (pc.usingBundle) {
                                    break;
                                }
                            }
                        } else {
                            var sdpMLineIndex = candidate.sdpMLineIndex;
                            if (candidate.sdpMid) {
                                for (var i = 0; i < pc.transceivers.length; i++) {
                                    if (pc.transceivers[i].mid === candidate.sdpMid) {
                                        sdpMLineIndex = i;
                                        break;
                                    }
                                }
                            }
                            var transceiver = pc.transceivers[sdpMLineIndex];
                            if (transceiver) {
                                if (transceiver.rejected) {
                                    return resolve();
                                }
                                var cand = Object.keys(candidate.candidate).length > 0 ?
                                    SDPUtils.parseCandidate(candidate.candidate) : {};
                                // Ignore Chrome's invalid candidates since Edge does not like them.
                                if (cand.protocol === 'tcp' && (cand.port === 0 || cand.port === 9)) {
                                    return resolve();
                                }
                                // Ignore RTCP candidates, we assume RTCP-MUX.
                                if (cand.component && cand.component !== 1) {
                                    return resolve();
                                }
                                // when using bundle, avoid adding candidates to the wrong
                                // ice transport. And avoid adding candidates added in the SDP.
                                if (sdpMLineIndex === 0 || (sdpMLineIndex > 0 &&
                                    transceiver.iceTransport !== pc.transceivers[0].iceTransport)) {
                                    if (!maybeAddCandidate(transceiver.iceTransport, cand)) {
                                        return reject(makeError('OperationError',
                                            'Can not add ICE candidate'));
                                    }
                                }

                                // update the remoteDescription.
                                var candidateString = candidate.candidate.trim();
                                if (candidateString.indexOf('a=') === 0) {
                                    candidateString = candidateString.substr(2);
                                }
                                sections = SDPUtils.getMediaSections(pc._remoteDescription.sdp);
                                sections[sdpMLineIndex] += 'a=' +
                                    (cand.type ? candidateString : 'end-of-candidates')
                                    + '\r\n';
                                pc._remoteDescription.sdp =
                                    SDPUtils.getDescription(pc._remoteDescription.sdp) +
                                    sections.join('');
                            } else {
                                return reject(makeError('OperationError',
                                    'Can not add ICE candidate'));
                            }
                        }
                        resolve();
                    });
                };

                RTCPeerConnection.prototype.getStats = function (selector) {
                    if (selector && selector instanceof window.MediaStreamTrack) {
                        var senderOrReceiver = null;
                        this.transceivers.forEach(function (transceiver) {
                            if (transceiver.rtpSender &&
                                transceiver.rtpSender.track === selector) {
                                senderOrReceiver = transceiver.rtpSender;
                            } else if (transceiver.rtpReceiver &&
                                transceiver.rtpReceiver.track === selector) {
                                senderOrReceiver = transceiver.rtpReceiver;
                            }
                        });
                        if (!senderOrReceiver) {
                            throw makeError('InvalidAccessError', 'Invalid selector.');
                        }
                        return senderOrReceiver.getStats();
                    }

                    var promises = [];
                    this.transceivers.forEach(function (transceiver) {
                        ['rtpSender', 'rtpReceiver', 'iceGatherer', 'iceTransport',
                            'dtlsTransport'].forEach(function (method) {
                            if (transceiver[method]) {
                                promises.push(transceiver[method].getStats());
                            }
                        });
                    });
                    return Promise.all(promises).then(function (allStats) {
                        var results = new Map();
                        allStats.forEach(function (stats) {
                            stats.forEach(function (stat) {
                                results.set(stat.id, stat);
                            });
                        });
                        return results;
                    });
                };

                // fix low-level stat names and return Map instead of object.
                var ortcObjects = ['RTCRtpSender', 'RTCRtpReceiver', 'RTCIceGatherer',
                    'RTCIceTransport', 'RTCDtlsTransport'];
                ortcObjects.forEach(function (ortcObjectName) {
                    var obj = window[ortcObjectName];
                    if (obj && obj.prototype && obj.prototype.getStats) {
                        var nativeGetstats = obj.prototype.getStats;
                        obj.prototype.getStats = function () {
                            return nativeGetstats.apply(this)
                                .then(function (nativeStats) {
                                    var mapStats = new Map();
                                    Object.keys(nativeStats).forEach(function (id) {
                                        nativeStats[id].type = fixStatsType(nativeStats[id]);
                                        mapStats.set(id, nativeStats[id]);
                                    });
                                    return mapStats;
                                });
                        };
                    }
                });

                // legacy callback shims. Should be moved to adapter.js some days.
                var methods = ['createOffer', 'createAnswer'];
                methods.forEach(function (method) {
                    var nativeMethod = RTCPeerConnection.prototype[method];
                    RTCPeerConnection.prototype[method] = function () {
                        var args = arguments;
                        if (typeof args[0] === 'function' ||
                            typeof args[1] === 'function') { // legacy
                            return nativeMethod.apply(this, [arguments[2]])
                                .then(function (description) {
                                    if (typeof args[0] === 'function') {
                                        args[0].apply(null, [description]);
                                    }
                                }, function (error) {
                                    if (typeof args[1] === 'function') {
                                        args[1].apply(null, [error]);
                                    }
                                });
                        }
                        return nativeMethod.apply(this, arguments);
                    };
                });

                methods = ['setLocalDescription', 'setRemoteDescription', 'addIceCandidate'];
                methods.forEach(function (method) {
                    var nativeMethod = RTCPeerConnection.prototype[method];
                    RTCPeerConnection.prototype[method] = function () {
                        var args = arguments;
                        if (typeof args[1] === 'function' ||
                            typeof args[2] === 'function') { // legacy
                            return nativeMethod.apply(this, arguments)
                                .then(function () {
                                    if (typeof args[1] === 'function') {
                                        args[1].apply(null);
                                    }
                                }, function (error) {
                                    if (typeof args[2] === 'function') {
                                        args[2].apply(null, [error]);
                                    }
                                });
                        }
                        return nativeMethod.apply(this, arguments);
                    };
                });

                // getStats is special. It doesn't have a spec legacy method yet we support
                // getStats(something, cb) without error callbacks.
                ['getStats'].forEach(function (method) {
                    var nativeMethod = RTCPeerConnection.prototype[method];
                    RTCPeerConnection.prototype[method] = function () {
                        var args = arguments;
                        if (typeof args[1] === 'function') {
                            return nativeMethod.apply(this, arguments)
                                .then(function () {
                                    if (typeof args[1] === 'function') {
                                        args[1].apply(null);
                                    }
                                });
                        }
                        return nativeMethod.apply(this, arguments);
                    };
                });

                return RTCPeerConnection;
            };

        }, {"sdp": 17}], 17: [function (require, module, exports) {
            /* eslint-env node */
            'use strict';

            // SDP helpers.
            var SDPUtils = {};

            // Generate an alphanumeric identifier for cname or mids.
            // TODO: use UUIDs instead? https://gist.github.com/jed/982883
            SDPUtils.generateIdentifier = function () {
                return Math.random().toString(36).substr(2, 10);
            };

            // The RTCP CNAME used by all peerconnections from the same JS.
            SDPUtils.localCName = SDPUtils.generateIdentifier();

            // Splits SDP into lines, dealing with both CRLF and LF.
            SDPUtils.splitLines = function (blob) {
                return blob.trim().split('\n').map(function (line) {
                    return line.trim();
                });
            };
            // Splits SDP into sessionpart and mediasections. Ensures CRLF.
            SDPUtils.splitSections = function (blob) {
                var parts = blob.split('\nm=');
                return parts.map(function (part, index) {
                    return (index > 0 ? 'm=' + part : part).trim() + '\r\n';
                });
            };

            // returns the session description.
            SDPUtils.getDescription = function (blob) {
                var sections = SDPUtils.splitSections(blob);
                return sections && sections[0];
            };

            // returns the individual media sections.
            SDPUtils.getMediaSections = function (blob) {
                var sections = SDPUtils.splitSections(blob);
                sections.shift();
                return sections;
            };

            // Returns lines that start with a certain prefix.
            SDPUtils.matchPrefix = function (blob, prefix) {
                return SDPUtils.splitLines(blob).filter(function (line) {
                    return line.indexOf(prefix) === 0;
                });
            };

            // Parses an ICE candidate line. Sample input:
            // candidate:702786350 2 udp 41819902 8.8.8.8 60769 typ relay raddr 8.8.8.8
            // rport 55996"
            SDPUtils.parseCandidate = function (line) {
                var parts;
                // Parse both variants.
                if (line.indexOf('a=candidate:') === 0) {
                    parts = line.substring(12).split(' ');
                } else {
                    parts = line.substring(10).split(' ');
                }

                var candidate = {
                    foundation: parts[0],
                    component: parseInt(parts[1], 10),
                    protocol: parts[2].toLowerCase(),
                    priority: parseInt(parts[3], 10),
                    ip: parts[4],
                    address: parts[4], // address is an alias for ip.
                    port: parseInt(parts[5], 10),
                    // skip parts[6] == 'typ'
                    type: parts[7]
                };

                for (var i = 8; i < parts.length; i += 2) {
                    switch (parts[i]) {
                        case 'raddr':
                            candidate.relatedAddress = parts[i + 1];
                            break;
                        case 'rport':
                            candidate.relatedPort = parseInt(parts[i + 1], 10);
                            break;
                        case 'tcptype':
                            candidate.tcpType = parts[i + 1];
                            break;
                        case 'ufrag':
                            candidate.ufrag = parts[i + 1]; // for backward compability.
                            candidate.usernameFragment = parts[i + 1];
                            break;
                        default: // extension handling, in particular ufrag
                            candidate[parts[i]] = parts[i + 1];
                            break;
                    }
                }
                return candidate;
            };

            // Translates a candidate object into SDP candidate attribute.
            SDPUtils.writeCandidate = function (candidate) {
                var sdp = [];
                sdp.push(candidate.foundation);
                sdp.push(candidate.component);
                sdp.push(candidate.protocol.toUpperCase());
                sdp.push(candidate.priority);
                sdp.push(candidate.address || candidate.ip);
                sdp.push(candidate.port);

                var type = candidate.type;
                sdp.push('typ');
                sdp.push(type);
                if (type !== 'host' && candidate.relatedAddress &&
                    candidate.relatedPort) {
                    sdp.push('raddr');
                    sdp.push(candidate.relatedAddress);
                    sdp.push('rport');
                    sdp.push(candidate.relatedPort);
                }
                if (candidate.tcpType && candidate.protocol.toLowerCase() === 'tcp') {
                    sdp.push('tcptype');
                    sdp.push(candidate.tcpType);
                }
                if (candidate.usernameFragment || candidate.ufrag) {
                    sdp.push('ufrag');
                    sdp.push(candidate.usernameFragment || candidate.ufrag);
                }
                return 'candidate:' + sdp.join(' ');
            };

            // Parses an ice-options line, returns an array of option tags.
            // a=ice-options:foo bar
            SDPUtils.parseIceOptions = function (line) {
                return line.substr(14).split(' ');
            };

            // Parses an rtpmap line, returns RTCRtpCoddecParameters. Sample input:
            // a=rtpmap:111 opus/48000/2
            SDPUtils.parseRtpMap = function (line) {
                var parts = line.substr(9).split(' ');
                var parsed = {
                    payloadType: parseInt(parts.shift(), 10) // was: id
                };

                parts = parts[0].split('/');

                parsed.name = parts[0];
                parsed.clockRate = parseInt(parts[1], 10); // was: clockrate
                parsed.channels = parts.length === 3 ? parseInt(parts[2], 10) : 1;
                // legacy alias, got renamed back to channels in ORTC.
                parsed.numChannels = parsed.channels;
                return parsed;
            };

            // Generate an a=rtpmap line from RTCRtpCodecCapability or
            // RTCRtpCodecParameters.
            SDPUtils.writeRtpMap = function (codec) {
                var pt = codec.payloadType;
                if (codec.preferredPayloadType !== undefined) {
                    pt = codec.preferredPayloadType;
                }
                var channels = codec.channels || codec.numChannels || 1;
                return 'a=rtpmap:' + pt + ' ' + codec.name + '/' + codec.clockRate +
                    (channels !== 1 ? '/' + channels : '') + '\r\n';
            };

            // Parses an a=extmap line (headerextension from RFC 5285). Sample input:
            // a=extmap:2 urn:ietf:params:rtp-hdrext:toffset
            // a=extmap:2/sendonly urn:ietf:params:rtp-hdrext:toffset
            SDPUtils.parseExtmap = function (line) {
                var parts = line.substr(9).split(' ');
                return {
                    id: parseInt(parts[0], 10),
                    direction: parts[0].indexOf('/') > 0 ? parts[0].split('/')[1] : 'sendrecv',
                    uri: parts[1]
                };
            };

            // Generates a=extmap line from RTCRtpHeaderExtensionParameters or
            // RTCRtpHeaderExtension.
            SDPUtils.writeExtmap = function (headerExtension) {
                return 'a=extmap:' + (headerExtension.id || headerExtension.preferredId) +
                    (headerExtension.direction && headerExtension.direction !== 'sendrecv'
                        ? '/' + headerExtension.direction
                        : '') +
                    ' ' + headerExtension.uri + '\r\n';
            };

            // Parses an ftmp line, returns dictionary. Sample input:
            // a=fmtp:96 vbr=on;cng=on
            // Also deals with vbr=on; cng=on
            SDPUtils.parseFmtp = function (line) {
                var parsed = {};
                var kv;
                var parts = line.substr(line.indexOf(' ') + 1).split(';');
                for (var j = 0; j < parts.length; j++) {
                    kv = parts[j].trim().split('=');
                    parsed[kv[0].trim()] = kv[1];
                }
                return parsed;
            };

            // Generates an a=ftmp line from RTCRtpCodecCapability or RTCRtpCodecParameters.
            SDPUtils.writeFmtp = function (codec) {
                var line = '';
                var pt = codec.payloadType;
                if (codec.preferredPayloadType !== undefined) {
                    pt = codec.preferredPayloadType;
                }
                if (codec.parameters && Object.keys(codec.parameters).length) {
                    var params = [];
                    Object.keys(codec.parameters).forEach(function (param) {
                        if (codec.parameters[param]) {
                            params.push(param + '=' + codec.parameters[param]);
                        } else {
                            params.push(param);
                        }
                    });
                    line += 'a=fmtp:' + pt + ' ' + params.join(';') + '\r\n';
                }
                return line;
            };

            // Parses an rtcp-fb line, returns RTCPRtcpFeedback object. Sample input:
            // a=rtcp-fb:98 nack rpsi
            SDPUtils.parseRtcpFb = function (line) {
                var parts = line.substr(line.indexOf(' ') + 1).split(' ');
                return {
                    type: parts.shift(),
                    parameter: parts.join(' ')
                };
            };
            // Generate a=rtcp-fb lines from RTCRtpCodecCapability or RTCRtpCodecParameters.
            SDPUtils.writeRtcpFb = function (codec) {
                var lines = '';
                var pt = codec.payloadType;
                if (codec.preferredPayloadType !== undefined) {
                    pt = codec.preferredPayloadType;
                }
                if (codec.rtcpFeedback && codec.rtcpFeedback.length) {
                    // FIXME: special handling for trr-int?
                    codec.rtcpFeedback.forEach(function (fb) {
                        lines += 'a=rtcp-fb:' + pt + ' ' + fb.type +
                            (fb.parameter && fb.parameter.length ? ' ' + fb.parameter : '') +
                            '\r\n';
                    });
                }
                return lines;
            };

            // Parses an RFC 5576 ssrc media attribute. Sample input:
            // a=ssrc:3735928559 cname:something
            SDPUtils.parseSsrcMedia = function (line) {
                var sp = line.indexOf(' ');
                var parts = {
                    ssrc: parseInt(line.substr(7, sp - 7), 10)
                };
                var colon = line.indexOf(':', sp);
                if (colon > -1) {
                    parts.attribute = line.substr(sp + 1, colon - sp - 1);
                    parts.value = line.substr(colon + 1);
                } else {
                    parts.attribute = line.substr(sp + 1);
                }
                return parts;
            };

            SDPUtils.parseSsrcGroup = function (line) {
                var parts = line.substr(13).split(' ');
                return {
                    semantics: parts.shift(),
                    ssrcs: parts.map(function (ssrc) {
                        return parseInt(ssrc, 10);
                    })
                };
            };

            // Extracts the MID (RFC 5888) from a media section.
            // returns the MID or undefined if no mid line was found.
            SDPUtils.getMid = function (mediaSection) {
                var mid = SDPUtils.matchPrefix(mediaSection, 'a=mid:')[0];
                if (mid) {
                    return mid.substr(6);
                }
            };

            SDPUtils.parseFingerprint = function (line) {
                var parts = line.substr(14).split(' ');
                return {
                    algorithm: parts[0].toLowerCase(), // algorithm is case-sensitive in Edge.
                    value: parts[1]
                };
            };

            // Extracts DTLS parameters from SDP media section or sessionpart.
            // FIXME: for consistency with other functions this should only
            //   get the fingerprint line as input. See also getIceParameters.
            SDPUtils.getDtlsParameters = function (mediaSection, sessionpart) {
                var lines = SDPUtils.matchPrefix(mediaSection + sessionpart,
                    'a=fingerprint:');
                // Note: a=setup line is ignored since we use the 'auto' role.
                // Note2: 'algorithm' is not case sensitive except in Edge.
                return {
                    role: 'auto',
                    fingerprints: lines.map(SDPUtils.parseFingerprint)
                };
            };

            // Serializes DTLS parameters to SDP.
            SDPUtils.writeDtlsParameters = function (params, setupType) {
                var sdp = 'a=setup:' + setupType + '\r\n';
                params.fingerprints.forEach(function (fp) {
                    sdp += 'a=fingerprint:' + fp.algorithm + ' ' + fp.value + '\r\n';
                });
                return sdp;
            };
            // Parses ICE information from SDP media section or sessionpart.
            // FIXME: for consistency with other functions this should only
            //   get the ice-ufrag and ice-pwd lines as input.
            SDPUtils.getIceParameters = function (mediaSection, sessionpart) {
                var lines = SDPUtils.splitLines(mediaSection);
                // Search in session part, too.
                lines = lines.concat(SDPUtils.splitLines(sessionpart));
                var iceParameters = {
                    usernameFragment: lines.filter(function (line) {
                        return line.indexOf('a=ice-ufrag:') === 0;
                    })[0].substr(12),
                    password: lines.filter(function (line) {
                        return line.indexOf('a=ice-pwd:') === 0;
                    })[0].substr(10)
                };
                return iceParameters;
            };

            // Serializes ICE parameters to SDP.
            SDPUtils.writeIceParameters = function (params) {
                return 'a=ice-ufrag:' + params.usernameFragment + '\r\n' +
                    'a=ice-pwd:' + params.password + '\r\n';
            };

            // Parses the SDP media section and returns RTCRtpParameters.
            SDPUtils.parseRtpParameters = function (mediaSection) {
                var description = {
                    codecs: [],
                    headerExtensions: [],
                    fecMechanisms: [],
                    rtcp: []
                };
                var lines = SDPUtils.splitLines(mediaSection);
                var mline = lines[0].split(' ');
                for (var i = 3; i < mline.length; i++) { // find all codecs from mline[3..]
                    var pt = mline[i];
                    var rtpmapline = SDPUtils.matchPrefix(
                        mediaSection, 'a=rtpmap:' + pt + ' ')[0];
                    if (rtpmapline) {
                        var codec = SDPUtils.parseRtpMap(rtpmapline);
                        var fmtps = SDPUtils.matchPrefix(
                            mediaSection, 'a=fmtp:' + pt + ' ');
                        // Only the first a=fmtp:<pt> is considered.
                        codec.parameters = fmtps.length ? SDPUtils.parseFmtp(fmtps[0]) : {};
                        codec.rtcpFeedback = SDPUtils.matchPrefix(
                            mediaSection, 'a=rtcp-fb:' + pt + ' ')
                            .map(SDPUtils.parseRtcpFb);
                        description.codecs.push(codec);
                        // parse FEC mechanisms from rtpmap lines.
                        switch (codec.name.toUpperCase()) {
                            case 'RED':
                            case 'ULPFEC':
                                description.fecMechanisms.push(codec.name.toUpperCase());
                                break;
                            default: // only RED and ULPFEC are recognized as FEC mechanisms.
                                break;
                        }
                    }
                }
                SDPUtils.matchPrefix(mediaSection, 'a=extmap:').forEach(function (line) {
                    description.headerExtensions.push(SDPUtils.parseExtmap(line));
                });
                // FIXME: parse rtcp.
                return description;
            };

            // Generates parts of the SDP media section describing the capabilities /
            // parameters.
            SDPUtils.writeRtpDescription = function (kind, caps) {
                var sdp = '';

                // Build the mline.
                sdp += 'm=' + kind + ' ';
                sdp += caps.codecs.length > 0 ? '9' : '0'; // reject if no codecs.
                sdp += ' UDP/TLS/RTP/SAVPF ';
                sdp += caps.codecs.map(function (codec) {
                    if (codec.preferredPayloadType !== undefined) {
                        return codec.preferredPayloadType;
                    }
                    return codec.payloadType;
                }).join(' ') + '\r\n';

                sdp += 'c=IN IP4 0.0.0.0\r\n';
                sdp += 'a=rtcp:9 IN IP4 0.0.0.0\r\n';

                // Add a=rtpmap lines for each codec. Also fmtp and rtcp-fb.
                caps.codecs.forEach(function (codec) {
                    sdp += SDPUtils.writeRtpMap(codec);
                    sdp += SDPUtils.writeFmtp(codec);
                    sdp += SDPUtils.writeRtcpFb(codec);
                });
                var maxptime = 0;
                caps.codecs.forEach(function (codec) {
                    if (codec.maxptime > maxptime) {
                        maxptime = codec.maxptime;
                    }
                });
                if (maxptime > 0) {
                    sdp += 'a=maxptime:' + maxptime + '\r\n';
                }
                sdp += 'a=rtcp-mux\r\n';

                if (caps.headerExtensions) {
                    caps.headerExtensions.forEach(function (extension) {
                        sdp += SDPUtils.writeExtmap(extension);
                    });
                }
                // FIXME: write fecMechanisms.
                return sdp;
            };

            // Parses the SDP media section and returns an array of
            // RTCRtpEncodingParameters.
            SDPUtils.parseRtpEncodingParameters = function (mediaSection) {
                var encodingParameters = [];
                var description = SDPUtils.parseRtpParameters(mediaSection);
                var hasRed = description.fecMechanisms.indexOf('RED') !== -1;
                var hasUlpfec = description.fecMechanisms.indexOf('ULPFEC') !== -1;

                // filter a=ssrc:... cname:, ignore PlanB-msid
                var ssrcs = SDPUtils.matchPrefix(mediaSection, 'a=ssrc:')
                    .map(function (line) {
                        return SDPUtils.parseSsrcMedia(line);
                    })
                    .filter(function (parts) {
                        return parts.attribute === 'cname';
                    });
                var primarySsrc = ssrcs.length > 0 && ssrcs[0].ssrc;
                var secondarySsrc;

                var flows = SDPUtils.matchPrefix(mediaSection, 'a=ssrc-group:FID')
                    .map(function (line) {
                        var parts = line.substr(17).split(' ');
                        return parts.map(function (part) {
                            return parseInt(part, 10);
                        });
                    });
                if (flows.length > 0 && flows[0].length > 1 && flows[0][0] === primarySsrc) {
                    secondarySsrc = flows[0][1];
                }

                description.codecs.forEach(function (codec) {
                    if (codec.name.toUpperCase() === 'RTX' && codec.parameters.apt) {
                        var encParam = {
                            ssrc: primarySsrc,
                            codecPayloadType: parseInt(codec.parameters.apt, 10)
                        };
                        if (primarySsrc && secondarySsrc) {
                            encParam.rtx = {ssrc: secondarySsrc};
                        }
                        encodingParameters.push(encParam);
                        if (hasRed) {
                            encParam = JSON.parse(JSON.stringify(encParam));
                            encParam.fec = {
                                ssrc: primarySsrc,
                                mechanism: hasUlpfec ? 'red+ulpfec' : 'red'
                            };
                            encodingParameters.push(encParam);
                        }
                    }
                });
                if (encodingParameters.length === 0 && primarySsrc) {
                    encodingParameters.push({
                        ssrc: primarySsrc
                    });
                }

                // we support both b=AS and b=TIAS but interpret AS as TIAS.
                var bandwidth = SDPUtils.matchPrefix(mediaSection, 'b=');
                if (bandwidth.length) {
                    if (bandwidth[0].indexOf('b=TIAS:') === 0) {
                        bandwidth = parseInt(bandwidth[0].substr(7), 10);
                    } else if (bandwidth[0].indexOf('b=AS:') === 0) {
                        // use formula from JSEP to convert b=AS to TIAS value.
                        bandwidth = parseInt(bandwidth[0].substr(5), 10) * 1000 * 0.95
                            - (50 * 40 * 8);
                    } else {
                        bandwidth = undefined;
                    }
                    encodingParameters.forEach(function (params) {
                        params.maxBitrate = bandwidth;
                    });
                }
                return encodingParameters;
            };

            // parses http://draft.ortc.org/#rtcrtcpparameters*
            SDPUtils.parseRtcpParameters = function (mediaSection) {
                var rtcpParameters = {};

                // Gets the first SSRC. Note tha with RTX there might be multiple
                // SSRCs.
                var remoteSsrc = SDPUtils.matchPrefix(mediaSection, 'a=ssrc:')
                    .map(function (line) {
                        return SDPUtils.parseSsrcMedia(line);
                    })
                    .filter(function (obj) {
                        return obj.attribute === 'cname';
                    })[0];
                if (remoteSsrc) {
                    rtcpParameters.cname = remoteSsrc.value;
                    rtcpParameters.ssrc = remoteSsrc.ssrc;
                }

                // Edge uses the compound attribute instead of reducedSize
                // compound is !reducedSize
                var rsize = SDPUtils.matchPrefix(mediaSection, 'a=rtcp-rsize');
                rtcpParameters.reducedSize = rsize.length > 0;
                rtcpParameters.compound = rsize.length === 0;

                // parses the rtcp-mux attrіbute.
                // Note that Edge does not support unmuxed RTCP.
                var mux = SDPUtils.matchPrefix(mediaSection, 'a=rtcp-mux');
                rtcpParameters.mux = mux.length > 0;

                return rtcpParameters;
            };

            // parses either a=msid: or a=ssrc:... msid lines and returns
            // the id of the MediaStream and MediaStreamTrack.
            SDPUtils.parseMsid = function (mediaSection) {
                var parts;
                var spec = SDPUtils.matchPrefix(mediaSection, 'a=msid:');
                if (spec.length === 1) {
                    parts = spec[0].substr(7).split(' ');
                    return {stream: parts[0], track: parts[1]};
                }
                var planB = SDPUtils.matchPrefix(mediaSection, 'a=ssrc:')
                    .map(function (line) {
                        return SDPUtils.parseSsrcMedia(line);
                    })
                    .filter(function (msidParts) {
                        return msidParts.attribute === 'msid';
                    });
                if (planB.length > 0) {
                    parts = planB[0].value.split(' ');
                    return {stream: parts[0], track: parts[1]};
                }
            };

            // SCTP
            // parses draft-ietf-mmusic-sctp-sdp-26 first and falls back
            // to draft-ietf-mmusic-sctp-sdp-05
            SDPUtils.parseSctpDescription = function (mediaSection) {
                var mline = SDPUtils.parseMLine(mediaSection);
                var maxSizeLine = SDPUtils.matchPrefix(mediaSection, 'a=max-message-size:');
                var maxMessageSize;
                if (maxSizeLine.length > 0) {
                    maxMessageSize = parseInt(maxSizeLine[0].substr(19), 10);
                }
                if (isNaN(maxMessageSize)) {
                    maxMessageSize = 65536;
                }
                var sctpPort = SDPUtils.matchPrefix(mediaSection, 'a=sctp-port:');
                if (sctpPort.length > 0) {
                    return {
                        port: parseInt(sctpPort[0].substr(12), 10),
                        protocol: mline.fmt,
                        maxMessageSize: maxMessageSize
                    };
                }
                var sctpMapLines = SDPUtils.matchPrefix(mediaSection, 'a=sctpmap:');
                if (sctpMapLines.length > 0) {
                    var parts = SDPUtils.matchPrefix(mediaSection, 'a=sctpmap:')[0]
                        .substr(10)
                        .split(' ');
                    return {
                        port: parseInt(parts[0], 10),
                        protocol: parts[1],
                        maxMessageSize: maxMessageSize
                    };
                }
            };

            // SCTP
            // outputs the draft-ietf-mmusic-sctp-sdp-26 version that all browsers
            // support by now receiving in this format, unless we originally parsed
            // as the draft-ietf-mmusic-sctp-sdp-05 format (indicated by the m-line
            // protocol of DTLS/SCTP -- without UDP/ or TCP/)
            SDPUtils.writeSctpDescription = function (media, sctp) {
                var output = [];
                if (media.protocol !== 'DTLS/SCTP') {
                    output = [
                        'm=' + media.kind + ' 9 ' + media.protocol + ' ' + sctp.protocol + '\r\n',
                        'c=IN IP4 0.0.0.0\r\n',
                        'a=sctp-port:' + sctp.port + '\r\n'
                    ];
                } else {
                    output = [
                        'm=' + media.kind + ' 9 ' + media.protocol + ' ' + sctp.port + '\r\n',
                        'c=IN IP4 0.0.0.0\r\n',
                        'a=sctpmap:' + sctp.port + ' ' + sctp.protocol + ' 65535\r\n'
                    ];
                }
                if (sctp.maxMessageSize !== undefined) {
                    output.push('a=max-message-size:' + sctp.maxMessageSize + '\r\n');
                }
                return output.join('');
            };

            // Generate a session ID for SDP.
            // https://tools.ietf.org/html/draft-ietf-rtcweb-jsep-20#section-5.2.1
            // recommends using a cryptographically random +ve 64-bit value
            // but right now this should be acceptable and within the right range
            SDPUtils.generateSessionId = function () {
                return Math.random().toString().substr(2, 21);
            };

            // Write boilder plate for start of SDP
            // sessId argument is optional - if not supplied it will
            // be generated randomly
            // sessVersion is optional and defaults to 2
            // sessUser is optional and defaults to 'thisisadapterortc'
            SDPUtils.writeSessionBoilerplate = function (sessId, sessVer, sessUser) {
                var sessionId;
                var version = sessVer !== undefined ? sessVer : 2;
                if (sessId) {
                    sessionId = sessId;
                } else {
                    sessionId = SDPUtils.generateSessionId();
                }
                var user = sessUser || 'thisisadapterortc';
                // FIXME: sess-id should be an NTP timestamp.
                return 'v=0\r\n' +
                    'o=' + user + ' ' + sessionId + ' ' + version +
                    ' IN IP4 127.0.0.1\r\n' +
                    's=-\r\n' +
                    't=0 0\r\n';
            };

            SDPUtils.writeMediaSection = function (transceiver, caps, type, stream) {
                var sdp = SDPUtils.writeRtpDescription(transceiver.kind, caps);

                // Map ICE parameters (ufrag, pwd) to SDP.
                sdp += SDPUtils.writeIceParameters(
                    transceiver.iceGatherer.getLocalParameters());

                // Map DTLS parameters to SDP.
                sdp += SDPUtils.writeDtlsParameters(
                    transceiver.dtlsTransport.getLocalParameters(),
                    type === 'offer' ? 'actpass' : 'active');

                sdp += 'a=mid:' + transceiver.mid + '\r\n';

                if (transceiver.direction) {
                    sdp += 'a=' + transceiver.direction + '\r\n';
                } else if (transceiver.rtpSender && transceiver.rtpReceiver) {
                    sdp += 'a=sendrecv\r\n';
                } else if (transceiver.rtpSender) {
                    sdp += 'a=sendonly\r\n';
                } else if (transceiver.rtpReceiver) {
                    sdp += 'a=recvonly\r\n';
                } else {
                    sdp += 'a=inactive\r\n';
                }

                if (transceiver.rtpSender) {
                    // spec.
                    var msid = 'msid:' + stream.id + ' ' +
                        transceiver.rtpSender.track.id + '\r\n';
                    sdp += 'a=' + msid;

                    // for Chrome.
                    sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].ssrc +
                        ' ' + msid;
                    if (transceiver.sendEncodingParameters[0].rtx) {
                        sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].rtx.ssrc +
                            ' ' + msid;
                        sdp += 'a=ssrc-group:FID ' +
                            transceiver.sendEncodingParameters[0].ssrc + ' ' +
                            transceiver.sendEncodingParameters[0].rtx.ssrc +
                            '\r\n';
                    }
                }
                // FIXME: this should be written by writeRtpDescription.
                sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].ssrc +
                    ' cname:' + SDPUtils.localCName + '\r\n';
                if (transceiver.rtpSender && transceiver.sendEncodingParameters[0].rtx) {
                    sdp += 'a=ssrc:' + transceiver.sendEncodingParameters[0].rtx.ssrc +
                        ' cname:' + SDPUtils.localCName + '\r\n';
                }
                return sdp;
            };

            // Gets the direction from the mediaSection or the sessionpart.
            SDPUtils.getDirection = function (mediaSection, sessionpart) {
                // Look for sendrecv, sendonly, recvonly, inactive, default to sendrecv.
                var lines = SDPUtils.splitLines(mediaSection);
                for (var i = 0; i < lines.length; i++) {
                    switch (lines[i]) {
                        case 'a=sendrecv':
                        case 'a=sendonly':
                        case 'a=recvonly':
                        case 'a=inactive':
                            return lines[i].substr(2);
                        default:
                        // FIXME: What should happen here?
                    }
                }
                if (sessionpart) {
                    return SDPUtils.getDirection(sessionpart);
                }
                return 'sendrecv';
            };

            SDPUtils.getKind = function (mediaSection) {
                var lines = SDPUtils.splitLines(mediaSection);
                var mline = lines[0].split(' ');
                return mline[0].substr(2);
            };

            SDPUtils.isRejected = function (mediaSection) {
                return mediaSection.split(' ', 2)[1] === '0';
            };

            SDPUtils.parseMLine = function (mediaSection) {
                var lines = SDPUtils.splitLines(mediaSection);
                var parts = lines[0].substr(2).split(' ');
                return {
                    kind: parts[0],
                    port: parseInt(parts[1], 10),
                    protocol: parts[2],
                    fmt: parts.slice(3).join(' ')
                };
            };

            SDPUtils.parseOLine = function (mediaSection) {
                var line = SDPUtils.matchPrefix(mediaSection, 'o=')[0];
                var parts = line.substr(2).split(' ');
                return {
                    username: parts[0],
                    sessionId: parts[1],
                    sessionVersion: parseInt(parts[2], 10),
                    netType: parts[3],
                    addressType: parts[4],
                    address: parts[5]
                };
            };

            // a very naive interpretation of a valid SDP.
            SDPUtils.isValidSDP = function (blob) {
                if (typeof blob !== 'string' || blob.length === 0) {
                    return false;
                }
                var lines = SDPUtils.splitLines(blob);
                for (var i = 0; i < lines.length; i++) {
                    if (lines[i].length < 2 || lines[i].charAt(1) !== '=') {
                        return false;
                    }
                    // TODO: check the modifier a bit more.
                }
                return true;
            };

            // Expose public methods.
            if (typeof module === 'object') {
                module.exports = SDPUtils;
            }

        }, {}]
    }, {}, [1])(1)
});