diff --git a/addons/gst-web/src/index.html b/addons/gst-web/src/index.html
index d145f24a..65629b24 100644
--- a/addons/gst-web/src/index.html
+++ b/addons/gst-web/src/index.html
@@ -408,7 +408,7 @@
     }
 });
 </script>
-<script src="lib/webrtc-adapter-v7.7.1.js?ts=1"></script>
+<script src="lib/webrtc-adapter-8.2.3.min.js?ts=1"></script>
 <script src="lib/vue-v2.7.16.min.js?ts=1"></script>
 <script src="lib/vuetify-1.5.24.min.js?ts=1"></script>
 <script src="lib/vue-spinner-v1.0.4.min.js?ts=1"></script>
diff --git a/addons/gst-web/src/lib/webrtc-adapter-8.2.3.min.js b/addons/gst-web/src/lib/webrtc-adapter-8.2.3.min.js
new file mode 100644
index 00000000..98b3380f
--- /dev/null
+++ b/addons/gst-web/src/lib/webrtc-adapter-8.2.3.min.js
@@ -0,0 +1 @@
+!function(e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define([],e):("undefined"!=typeof window?window:"undefined"!=typeof global?global:"undefined"!=typeof self?self:this).adapter=e()}(function(){return function n(i,o,a){function s(t,e){if(!o[t]){if(!i[t]){var r="function"==typeof require&&require;if(!e&&r)return r(t,!0);if(c)return c(t,!0);throw(e=new Error("Cannot find module '"+t+"'")).code="MODULE_NOT_FOUND",e}r=o[t]={exports:{}},i[t][0].call(r.exports,function(e){return s(i[t][1][e]||e)},r,r.exports,n,i,o,a)}return o[t].exports}for(var c="function"==typeof require&&require,e=0;e<a.length;e++)s(a[e]);return s}({1:[function(e,t,r){"use strict";e=(0,e("./adapter_factory.js").adapterFactory)({window:"undefined"==typeof window?void 0:window});t.exports=e},{"./adapter_factory.js":2}],2:[function(e,t,r){"use strict";function a(e){return(a="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}Object.defineProperty(r,"__esModule",{value:!0}),r.adapterFactory=function(){var e=(0<arguments.length&&void 0!==arguments[0]?arguments[0]:{}).window,t=1<arguments.length&&void 0!==arguments[1]?arguments[1]:{shimChrome:!0,shimFirefox:!0,shimSafari:!0},r=o.log,n=o.detectBrowser(e),i={browserDetails:n,commonShim:u,extractVersion:o.extractVersion,disableLog:o.disableLog,disableWarnings:o.disableWarnings,sdp:d};switch(n.browser){case"chrome":if(!s||!s.shimPeerConnection||!t.shimChrome)return r("Chrome shim is not included in this adapter release."),i;if(null===n.version)return r("Chrome shim can not determine version, not shimming."),i;r("adapter.js shimming chrome."),i.browserShim=s,u.shimAddIceCandidateNullOrEmpty(e,n),u.shimParameterlessSetLocalDescription(e,n),s.shimGetUserMedia(e,n),s.shimMediaStream(e,n),s.shimPeerConnection(e,n),s.shimOnTrack(e,n),s.shimAddTrackRemoveTrack(e,n),s.shimGetSendersWithDtmf(e,n),s.shimGetStats(e,n),s.shimSenderReceiverGetStats(e,n),s.fixNegotiationNeeded(e,n),u.shimRTCIceCandidate(e,n),u.shimRTCIceCandidateRelayProtocol(e,n),u.shimConnectionState(e,n),u.shimMaxMessageSize(e,n),u.shimSendThrowTypeError(e,n),u.removeExtmapAllowMixed(e,n);break;case"firefox":if(!c||!c.shimPeerConnection||!t.shimFirefox)return r("Firefox shim is not included in this adapter release."),i;r("adapter.js shimming firefox."),i.browserShim=c,u.shimAddIceCandidateNullOrEmpty(e,n),u.shimParameterlessSetLocalDescription(e,n),c.shimGetUserMedia(e,n),c.shimPeerConnection(e,n),c.shimOnTrack(e,n),c.shimRemoveStream(e,n),c.shimSenderGetStats(e,n),c.shimReceiverGetStats(e,n),c.shimRTCDataChannel(e,n),c.shimAddTransceiver(e,n),c.shimGetParameters(e,n),c.shimCreateOffer(e,n),c.shimCreateAnswer(e,n),u.shimRTCIceCandidate(e,n),u.shimConnectionState(e,n),u.shimMaxMessageSize(e,n),u.shimSendThrowTypeError(e,n);break;case"safari":if(!p||!t.shimSafari)return r("Safari shim is not included in this adapter release."),i;r("adapter.js shimming safari."),i.browserShim=p,u.shimAddIceCandidateNullOrEmpty(e,n),u.shimParameterlessSetLocalDescription(e,n),p.shimRTCIceServerUrls(e,n),p.shimCreateOfferLegacy(e,n),p.shimCallbacksAPI(e,n),p.shimLocalStreamsAPI(e,n),p.shimRemoteStreamsAPI(e,n),p.shimTrackEventTransceiver(e,n),p.shimGetUserMedia(e,n),p.shimAudioContext(e,n),u.shimRTCIceCandidate(e,n),u.shimRTCIceCandidateRelayProtocol(e,n),u.shimMaxMessageSize(e,n),u.shimSendThrowTypeError(e,n),u.removeExtmapAllowMixed(e,n);break;default:r("Unsupported browser!")}return i};var o=n(e("./utils")),s=n(e("./chrome/chrome_shim")),c=n(e("./firefox/firefox_shim")),p=n(e("./safari/safari_shim")),u=n(e("./common_shim")),d=n(e("sdp"));function f(e){if("function"!=typeof WeakMap)return null;var t=new WeakMap,r=new WeakMap;return(f=function(e){return e?r:t})(e)}function n(e,t){if(!t&&e&&e.__esModule)return e;if(null===e||"object"!==a(e)&&"function"!=typeof e)return{default:e};t=f(t);if(t&&t.has(e))return t.get(e);var r,n,i={},o=Object.defineProperty&&Object.getOwnPropertyDescriptor;for(r in e)"default"!==r&&Object.prototype.hasOwnProperty.call(e,r)&&((n=o?Object.getOwnPropertyDescriptor(e,r):null)&&(n.get||n.set)?Object.defineProperty(i,r,n):i[r]=e[r]);return i.default=e,t&&t.set(e,i),i}},{"./chrome/chrome_shim":3,"./common_shim":6,"./firefox/firefox_shim":7,"./safari/safari_shim":10,"./utils":11,sdp:12}],3:[function(e,t,r){"use strict";Object.defineProperty(r,"__esModule",{value:!0}),r.fixNegotiationNeeded=function(e,r){i.wrapPeerConnectionEvent(e,"negotiationneeded",function(e){var t=e.target;if(!(r.version<72||t.getConfiguration&&"plan-b"===t.getConfiguration().sdpSemantics)||"stable"===t.signalingState)return e})},r.shimAddTrackRemoveTrack=function(i,e){if(i.RTCPeerConnection){if(i.RTCPeerConnection.prototype.addTrack&&65<=e.version)return p(i);var r=i.RTCPeerConnection.prototype.getLocalStreams,n=(i.RTCPeerConnection.prototype.getLocalStreams=function(){var t=this,e=r.apply(this);return 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e.RTCRtpSender.prototype)&&(a=e.RTCPeerConnection.prototype.getSenders,e.RTCPeerConnection.prototype.getSenders=function(){var t=this,e=a.apply(this,[]);return e.forEach(function(e){return e._pc=t}),e},Object.defineProperty(e.RTCRtpSender.prototype,"dtmf",{get:function(){return void 0===this._dtmf&&("audio"===this.track.kind?this._dtmf=this._pc.createDTMFSender(this.track):this._dtmf=null),this._dtmf}}))}},r.shimGetStats=function(e){var a;e.RTCPeerConnection&&(a=e.RTCPeerConnection.prototype.getStats,e.RTCPeerConnection.prototype.getStats=function(){var r=this,e=Array.prototype.slice.call(arguments),t=e[0],n=e[1],e=e[2];if(0<arguments.length&&"function"==typeof t)return a.apply(this,arguments);if(0===a.length&&(0===arguments.length||"function"!=typeof t))return a.apply(this,[]);var i=function(e){var n={};return e.result().forEach(function(t){var 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0<arguments.length&&arguments[0]instanceof e.MediaStreamTrack?(t=arguments[0],this.getSenders().forEach(function(e){e.track===t&&(r?i=!0:r=e)}),this.getReceivers().forEach(function(e){return e.track===t&&(n?i=!0:n=e),e.track===t}),i||r&&n?Promise.reject(new DOMException("There are more than one sender or receiver for the track.","InvalidAccessError")):r?r.getStats():n?n.getStats():Promise.reject(new DOMException("There is no sender or receiver for the track.","InvalidAccessError"))):o.apply(this,arguments)}))};var i=function(e,t){if(!t&&e&&e.__esModule)return e;if(null===e||"object"!==s(e)&&"function"!=typeof e)return{default:e};t=a(t);if(t&&t.has(e))return t.get(e);var r,n={},i=Object.defineProperty&&Object.getOwnPropertyDescriptor;for(r in e){var o;"default"!==r&&Object.prototype.hasOwnProperty.call(e,r)&&((o=i?Object.getOwnPropertyDescriptor(e,r):null)&&(o.get||o.set)?Object.defineProperty(n,r,o):n[r]=e[r])}n.default=e,t&&t.set(e,n);return n}(e("../utils.js")),n=e("./getusermedia"),o=e("./getdisplaymedia");function a(e){if("function"!=typeof WeakMap)return null;var t=new WeakMap,r=new WeakMap;return(a=function(e){return e?r:t})(e)}function c(e,t,r){return(t=function(e){e=function(e,t){if("object"!==s(e)||null===e)return e;var r=e[Symbol.toPrimitive];if(void 0===r)return("string"===t?String:Number)(e);r=r.call(e,t||"default");if("object"!==s(r))return r;throw new TypeError("@@toPrimitive must return a primitive value.")}(e,"string");return"symbol"===s(e)?e:String(e)}(t))in e?Object.defineProperty(e,t,{value:r,enumerable:!0,configurable:!0,writable:!0}):e[t]=r,e}function s(e){return(s="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(e){return typeof e}:function(e){return e&&"function"==typeof Symbol&&e.constructor===Symbol&&e!==Symbol.prototype?"symbol":typeof e})(e)}function p(e){e.RTCPeerConnection.prototype.getLocalStreams=function(){var t=this;return this._shimmedLocalStreams=this._shimmedLocalStreams||{},Object.keys(this._shimmedLocalStreams).map(function(e){return t._shimmedLocalStreams[e][0]})};var n=e.RTCPeerConnection.prototype.addTrack,i=(e.RTCPeerConnection.prototype.addTrack=function(e,t){if(!t)return n.apply(this,arguments);this._shimmedLocalStreams=this._shimmedLocalStreams||{};var r=n.apply(this,arguments);return this._shimmedLocalStreams[t.id]?-1===this._shimmedLocalStreams[t.id].indexOf(r)&&this._shimmedLocalStreams[t.id].push(r):this._shimmedLocalStreams[t.id]=[t,r],r},e.RTCPeerConnection.prototype.addStream),t=(e.RTCPeerConnection.prototype.addStream=function(e){var r=this,t=(this._shimmedLocalStreams=this._shimmedLocalStreams||{},e.getTracks().forEach(function(t){if(r.getSenders().find(function(e){return e.track===t}))throw new DOMException("Track already exists.","InvalidAccessError")}),this.getSenders()),n=(i.apply(this,arguments),this.getSenders().filter(function(e){return-1===t.indexOf(e)}));this._shimmedLocalStreams[e.id]=[e].concat(n)},e.RTCPeerConnection.prototype.removeStream),o=(e.RTCPeerConnection.prototype.removeStream=function(e){return this._shimmedLocalStreams=this._shimmedLocalStreams||{},delete this._shimmedLocalStreams[e.id],t.apply(this,arguments)},e.RTCPeerConnection.prototype.removeTrack);e.RTCPeerConnection.prototype.removeTrack=function(r){var n=this;return this._shimmedLocalStreams=this._shimmedLocalStreams||{},r&&Object.keys(this._shimmedLocalStreams).forEach(function(e){var t=n._shimmedLocalStreams[e].indexOf(r);-1!==t&&n._shimmedLocalStreams[e].splice(t,1),1===n._shimmedLocalStreams[e].length&&delete n._shimmedLocalStreams[e]}),o.apply(this,arguments)}}},{"../utils.js":11,"./getdisplaymedia":4,"./getusermedia":5}],4:[function(e,t,r){"use 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t={codecs:[],headerExtensions:[],fecMechanisms:[],rtcp:[]},r=p.splitLines(e)[0].split(" ");t.profile=r[2];for(var n=3;n<r.length;n++){var i=r[n],o=p.matchPrefix(e,"a=rtpmap:"+i+" ")[0];if(o){var a=p.parseRtpMap(o),o=p.matchPrefix(e,"a=fmtp:"+i+" ");switch(a.parameters=o.length?p.parseFmtp(o[0]):{},a.rtcpFeedback=p.matchPrefix(e,"a=rtcp-fb:"+i+" ").map(p.parseRtcpFb),t.codecs.push(a),a.name.toUpperCase()){case"RED":case"ULPFEC":t.fecMechanisms.push(a.name.toUpperCase())}}}p.matchPrefix(e,"a=extmap:").forEach(function(e){t.headerExtensions.push(p.parseExtmap(e))});var s=p.matchPrefix(e,"a=rtcp-fb:* ").map(p.parseRtcpFb);return t.codecs.forEach(function(e){s.forEach(function(t){e.rtcpFeedback.find(function(e){return e.type===t.type&&e.parameter===t.parameter})||e.rtcpFeedback.push(t)})}),t},p.writeRtpDescription=function(e,t){var r="",n=(r=(r=(r=(r=(r+="m="+e+" ")+(0<t.codecs.length?"9":"0"))+(" "+(t.profile||"UDP/TLS/RTP/SAVPF")+" "))+(t.codecs.map(function(e){return void 0!==e.preferredPayloadType?e.preferredPayloadType:e.payloadType}).join(" ")+"\r\n"))+"c=IN IP4 0.0.0.0\r\n"+"a=rtcp:9 IN IP4 0.0.0.0\r\n",t.codecs.forEach(function(e){r=(r=(r+=p.writeRtpMap(e))+p.writeFmtp(e))+p.writeRtcpFb(e)}),0);return t.codecs.forEach(function(e){e.maxptime>n&&(n=e.maxptime)}),0<n&&(r+="a=maxptime:"+n+"\r\n"),t.headerExtensions&&t.headerExtensions.forEach(function(e){r+=p.writeExtmap(e)}),r},p.parseRtpEncodingParameters=function(e){var t=[],r=p.parseRtpParameters(e),n=-1!==r.fecMechanisms.indexOf("RED"),i=-1!==r.fecMechanisms.indexOf("ULPFEC"),o=p.matchPrefix(e,"a=ssrc:").map(function(e){return p.parseSsrcMedia(e)}).filter(function(e){return"cname"===e.attribute}),a=0<o.length&&o[0].ssrc,s=void 0,o=p.matchPrefix(e,"a=ssrc-group:FID").map(function(e){return e.substring(17).split(" ").map(function(e){return parseInt(e,10)})}),c=(0<o.length&&1<o[0].length&&o[0][0]===a&&(s=o[0][1]),r.codecs.forEach(function(e){"RTX"===e.name.toUpperCase()&&e.parameters.apt&&(e={ssrc:a,codecPayloadType:parseInt(e.parameters.apt,10)},a&&s&&(e.rtx={ssrc:s}),t.push(e),n&&((e=JSON.parse(JSON.stringify(e))).fec={ssrc:a,mechanism:i?"red+ulpfec":"red"},t.push(e)))}),0===t.length&&a&&t.push({ssrc:a}),p.matchPrefix(e,"b="));return c.length&&(c=0===c[0].indexOf("b=TIAS:")?parseInt(c[0].substring(7),10):0===c[0].indexOf("b=AS:")?1e3*parseInt(c[0].substring(5),10)*.95-16e3:void 0,t.forEach(function(e){e.maxBitrate=c})),t},p.parseRtcpParameters=function(e){var t={},r=p.matchPrefix(e,"a=ssrc:").map(function(e){return p.parseSsrcMedia(e)}).filter(function(e){return"cname"===e.attribute})[0],r=(r&&(t.cname=r.value,t.ssrc=r.ssrc),p.matchPrefix(e,"a=rtcp-rsize")),r=(t.reducedSize=0<r.length,t.compound=0===r.length,p.matchPrefix(e,"a=rtcp-mux"));return t.mux=0<r.length,t},p.writeRtcpParameters=function(e){var t="";return e.reducedSize&&(t+="a=rtcp-rsize\r\n"),e.mux&&(t+="a=rtcp-mux\r\n"),void 0!==e.ssrc&&e.cname&&(t+="a=ssrc:"+e.ssrc+" cname:"+e.cname+"\r\n"),t},p.parseMsid=function(e){var t=void 0,r=p.matchPrefix(e,"a=msid:");if(1===r.length)return{stream:(t=r[0].substring(7).split(" "))[0],track:t[1]};r=p.matchPrefix(e,"a=ssrc:").map(function(e){return p.parseSsrcMedia(e)}).filter(function(e){return"msid"===e.attribute});return 0<r.length?{stream:(t=r[0].value.split(" "))[0],track:t[1]}:void 0},p.parseSctpDescription=function(e){var t=p.parseMLine(e),r=p.matchPrefix(e,"a=max-message-size:"),n=void 0,r=(0<r.length&&(n=parseInt(r[0].substring(19),10)),isNaN(n)&&(n=65536),p.matchPrefix(e,"a=sctp-port:"));if(0<r.length)return{port:parseInt(r[0].substring(12),10),protocol:t.fmt,maxMessageSize:n};r=p.matchPrefix(e,"a=sctpmap:");return 0<r.length?(t=r[0].substring(10).split(" "),{port:parseInt(t[0],10),protocol:t[1],maxMessageSize:n}):void 0},p.writeSctpDescription=function(e,t){var r=[],r="DTLS/SCTP"!==e.protocol?["m="+e.kind+" 9 "+e.protocol+" "+t.protocol+"\r\n","c=IN IP4 0.0.0.0\r\n","a=sctp-port:"+t.port+"\r\n"]:["m="+e.kind+" 9 "+e.protocol+" "+t.port+"\r\n","c=IN IP4 0.0.0.0\r\n","a=sctpmap:"+t.port+" "+t.protocol+" 65535\r\n"];return void 0!==t.maxMessageSize&&r.push("a=max-message-size:"+t.maxMessageSize+"\r\n"),r.join("")},p.generateSessionId=function(){return Math.random().toString().substr(2,22)},p.writeSessionBoilerplate=function(e,t,r){t=void 0!==t?t:2;return"v=0\r\no="+(r||"thisisadapterortc")+" "+(e||p.generateSessionId())+" "+t+" IN IP4 127.0.0.1\r\ns=-\r\nt=0 0\r\n"},p.getDirection=function(e,t){for(var r=p.splitLines(e),n=0;n<r.length;n++)switch(r[n]){case"a=sendrecv":case"a=sendonly":case"a=recvonly":case"a=inactive":return r[n].substring(2)}return t?p.getDirection(t):"sendrecv"},p.getKind=function(e){return p.splitLines(e)[0].split(" ")[0].substring(2)},p.isRejected=function(e){return"0"===e.split(" ",2)[1]},p.parseMLine=function(e){e=p.splitLines(e)[0].substring(2).split(" ");return{kind:e[0],port:parseInt(e[1],10),protocol:e[2],fmt:e.slice(3).join(" ")}},p.parseOLine=function(e){e=p.matchPrefix(e,"o=")[0].substring(2).split(" ");return{username:e[0],sessionId:e[1],sessionVersion:parseInt(e[2],10),netType:e[3],addressType:e[4],address:e[5]}},p.isValidSDP=function(e){if("string"!=typeof e||0===e.length)return!1;for(var t=p.splitLines(e),r=0;r<t.length;r++)if(t[r].length<2||"="!==t[r].charAt(1))return!1;return!0},"object"===(void 0===t?"undefined":n(t))&&(t.exports=p)},{}]},{},[1])(1)});
\ No newline at end of file
diff --git a/addons/gst-web/src/lib/webrtc-adapter-v7.7.1.js b/addons/gst-web/src/lib/webrtc-adapter-v7.7.1.js
deleted file mode 100644
index ec3236b9..00000000
--- a/addons/gst-web/src/lib/webrtc-adapter-v7.7.1.js
+++ /dev/null
@@ -1,5621 +0,0 @@
-(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: typeof window === 'undefined' ? undefined : 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;
-      }
-      if (browserDetails.version === null) {
-        logging('Chrome shim can not determine version, not shimming.');
-        return adapter;
-      }
-      logging('adapter.js shimming chrome.');
-      // Export to the adapter global object visible in the browser.
-      adapter.browserShim = chromeShim;
-
-      // Must be called before shimPeerConnection.
-      commonShim.shimAddIceCandidateNullOrEmpty(window, browserDetails);
-
-      chromeShim.shimGetUserMedia(window, browserDetails);
-      chromeShim.shimMediaStream(window, browserDetails);
-      chromeShim.shimPeerConnection(window, browserDetails);
-      chromeShim.shimOnTrack(window, browserDetails);
-      chromeShim.shimAddTrackRemoveTrack(window, browserDetails);
-      chromeShim.shimGetSendersWithDtmf(window, browserDetails);
-      chromeShim.shimGetStats(window, browserDetails);
-      chromeShim.shimSenderReceiverGetStats(window, browserDetails);
-      chromeShim.fixNegotiationNeeded(window, browserDetails);
-
-      commonShim.shimRTCIceCandidate(window, browserDetails);
-      commonShim.shimConnectionState(window, browserDetails);
-      commonShim.shimMaxMessageSize(window, browserDetails);
-      commonShim.shimSendThrowTypeError(window, browserDetails);
-      commonShim.removeExtmapAllowMixed(window, browserDetails);
-      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;
-
-      // Must be called before shimPeerConnection.
-      commonShim.shimAddIceCandidateNullOrEmpty(window, browserDetails);
-
-      firefoxShim.shimGetUserMedia(window, browserDetails);
-      firefoxShim.shimPeerConnection(window, browserDetails);
-      firefoxShim.shimOnTrack(window, browserDetails);
-      firefoxShim.shimRemoveStream(window, browserDetails);
-      firefoxShim.shimSenderGetStats(window, browserDetails);
-      firefoxShim.shimReceiverGetStats(window, browserDetails);
-      firefoxShim.shimRTCDataChannel(window, browserDetails);
-      firefoxShim.shimAddTransceiver(window, browserDetails);
-      firefoxShim.shimGetParameters(window, browserDetails);
-      firefoxShim.shimCreateOffer(window, browserDetails);
-      firefoxShim.shimCreateAnswer(window, browserDetails);
-
-      commonShim.shimRTCIceCandidate(window, browserDetails);
-      commonShim.shimConnectionState(window, browserDetails);
-      commonShim.shimMaxMessageSize(window, browserDetails);
-      commonShim.shimSendThrowTypeError(window, browserDetails);
-      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, browserDetails);
-      edgeShim.shimGetDisplayMedia(window, browserDetails);
-      edgeShim.shimPeerConnection(window, browserDetails);
-      edgeShim.shimReplaceTrack(window, browserDetails);
-
-      // the edge shim implements the full RTCIceCandidate object.
-
-      commonShim.shimMaxMessageSize(window, browserDetails);
-      commonShim.shimSendThrowTypeError(window, browserDetails);
-      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;
-
-      // Must be called before shimCallbackAPI.
-      commonShim.shimAddIceCandidateNullOrEmpty(window, browserDetails);
-
-      safariShim.shimRTCIceServerUrls(window, browserDetails);
-      safariShim.shimCreateOfferLegacy(window, browserDetails);
-      safariShim.shimCallbacksAPI(window, browserDetails);
-      safariShim.shimLocalStreamsAPI(window, browserDetails);
-      safariShim.shimRemoteStreamsAPI(window, browserDetails);
-      safariShim.shimTrackEventTransceiver(window, browserDetails);
-      safariShim.shimGetUserMedia(window, browserDetails);
-      safariShim.shimAudioContext(window, browserDetails);
-
-      commonShim.shimRTCIceCandidate(window, browserDetails);
-      commonShim.shimMaxMessageSize(window, browserDetails);
-      commonShim.shimSendThrowTypeError(window, browserDetails);
-      commonShim.removeExtmapAllowMixed(window, browserDetails);
-      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, browserDetails) {
-  if (!window.RTCPeerConnection) {
-    return;
-  }
-  // 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, browserDetails) {
-  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];
-    });
-  }
-}
-
-// Attempt to fix ONN in plan-b mode.
-function fixNegotiationNeeded(window, browserDetails) {
-  utils.wrapPeerConnectionEvent(window, 'negotiationneeded', function (e) {
-    var pc = e.target;
-    if (browserDetails.version < 72 || pc.getConfiguration && pc.getConfiguration().sdpSemantics === 'plan-b') {
-      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, browserDetails) {
-  var navigator = window && window.navigator;
-
-  if (!navigator.mediaDevices) {
-    return;
-  }
-
-  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.removeExtmapAllowMixed = removeExtmapAllowMixed;
-exports.shimAddIceCandidateNullOrEmpty = shimAddIceCandidateNullOrEmpty;
-
-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, browserDetails) {
-  if (!window.RTCPeerConnection) {
-    return;
-  }
-
-  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 removeExtmapAllowMixed(window, browserDetails) {
-  /* remove a=extmap-allow-mixed for webrtc.org < M71 */
-  if (!window.RTCPeerConnection) {
-    return;
-  }
-  if (browserDetails.browser === 'chrome' && browserDetails.version >= 71) {
-    return;
-  }
-  if (browserDetails.browser === 'safari' && browserDetails.version >= 605) {
-    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) {
-      var sdp = desc.sdp.split('\n').filter(function (line) {
-        return line.trim() !== 'a=extmap-allow-mixed';
-      }).join('\n');
-      // Safari enforces read-only-ness of RTCSessionDescription fields.
-      if (window.RTCSessionDescription && desc instanceof window.RTCSessionDescription) {
-        arguments[0] = new window.RTCSessionDescription({
-          type: desc.type,
-          sdp: sdp
-        });
-      } else {
-        desc.sdp = sdp;
-      }
-    }
-    return nativeSRD.apply(this, arguments);
-  };
-}
-
-function shimAddIceCandidateNullOrEmpty(window, browserDetails) {
-  // Support for addIceCandidate(null or undefined)
-  // as well as addIceCandidate({candidate: "", ...})
-  // https://bugs.chromium.org/p/chromium/issues/detail?id=978582
-  // Note: must be called before other polyfills which change the signature.
-  if (!(window.RTCPeerConnection && window.RTCPeerConnection.prototype)) {
-    return;
-  }
-  var nativeAddIceCandidate = window.RTCPeerConnection.prototype.addIceCandidate;
-  if (!nativeAddIceCandidate || nativeAddIceCandidate.length === 0) {
-    return;
-  }
-  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 for ignoring exists for Chrome M77+.
-    // Safari ignores as well, exact version unknown but works in the same
-    // version that also ignores addIceCandidate(null).
-    if ((browserDetails.browser === 'chrome' && browserDetails.version < 78 || browserDetails.browser === 'firefox' && browserDetails.version < 68 || browserDetails.browser === 'safari') && arguments[0] && arguments[0].candidate === '') {
-      return Promise.resolve();
-    }
-    return nativeAddIceCandidate.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, browserDetails) {
-  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.shimGetParameters = shimGetParameters;
-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, browserDetails) {
-  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];
-    });
-  }
-
-  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) ||
-        // Avoid being fooled by patched getParameters() below.
-        params.encodings.length === 1 && Object.keys(params.encodings[0]).length === 0) {
-          params.encodings = initParameters.sendEncodings;
-          sender.sendEncodings = initParameters.sendEncodings;
-          this.setParametersPromises.push(sender.setParameters(params).then(function () {
-            delete sender.sendEncodings;
-          }).catch(function () {
-            delete sender.sendEncodings;
-          }));
-        }
-      }
-      return transceiver;
-    };
-  }
-}
-
-function shimGetParameters(window) {
-  if (!((typeof window === 'undefined' ? 'undefined' : _typeof(window)) === 'object' && window.RTCRtpSender)) {
-    return;
-  }
-  var origGetParameters = window.RTCRtpSender.prototype.getParameters;
-  if (origGetParameters) {
-    window.RTCRtpSender.prototype.getParameters = function getParameters() {
-      var params = origGetParameters.apply(this, arguments);
-      if (!('encodings' in params)) {
-        params.encodings = [].concat(this.sendEncodings || [{}]);
-      }
-      return params;
-    };
-  }
-}
-
-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, browserDetails) {
-  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;
-exports.shimAudioContext = shimAudioContext;
-
-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 _this2 = this;
-
-      for (var _len = arguments.length, streams = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
-        streams[_key - 1] = arguments[_key];
-      }
-
-      if (streams) {
-        streams.forEach(function (stream) {
-          if (!_this2._localStreams) {
-            _this2._localStreams = [stream];
-          } else if (!_this2._localStreams.includes(stream)) {
-            _this2._localStreams.push(stream);
-          }
-        });
-      }
-      return _addTrack.apply(this, arguments);
-    };
-  }
-  if (!('removeStream' in window.RTCPeerConnection.prototype)) {
-    window.RTCPeerConnection.prototype.removeStream = function removeStream(stream) {
-      var _this3 = 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)) {
-          _this3.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 _this4 = 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 (!_this4._remoteStreams) {
-              _this4._remoteStreams = [];
-            }
-            if (_this4._remoteStreams.includes(stream)) {
-              return;
-            }
-            _this4._remoteStreams.push(stream);
-            var event = new Event('addstream');
-            event.stream = stream;
-            _this4.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) {
-  if (!window.RTCPeerConnection) {
-    return;
-  }
-  // 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 OrigPeerConnection) {
-    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);
-  };
-}
-
-function shimAudioContext(window) {
-  if ((typeof window === 'undefined' ? 'undefined' : _typeof(window)) !== 'object' || window.AudioContext) {
-    return;
-  }
-  window.AudioContext = window.webkitAudioContext;
-}
-
-},{"../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) {
-        if (cb.handleEvent) {
-          cb.handleEvent(modifiedEvent);
-        } else {
-          cb(modifiedEvent);
-        }
-      }
-    };
-    this._eventMap = this._eventMap || {};
-    if (!this._eventMap[eventNameToWrap]) {
-      this._eventMap[eventNameToWrap] = new Map();
-    }
-    this._eventMap[eventNameToWrap].set(cb, wrappedCallback);
-    return nativeAddEventListener.apply(this, [nativeEventName, wrappedCallback]);
-  };
-
-  var nativeRemoveEventListener = proto.removeEventListener;
-  proto.removeEventListener = function (nativeEventName, cb) {
-    if (nativeEventName !== eventNameToWrap || !this._eventMap || !this._eventMap[eventNameToWrap]) {
-      return nativeRemoveEventListener.apply(this, arguments);
-    }
-    if (!this._eventMap[eventNameToWrap].has(cb)) {
-      return nativeRemoveEventListener.apply(this, arguments);
-    }
-    var unwrappedCb = this._eventMap[eventNameToWrap].get(cb);
-    this._eventMap[eventNameToWrap].delete(cb);
-    if (this._eventMap[eventNameToWrap].size === 0) {
-      delete this._eventMap[eventNameToWrap];
-    }
-    if (Object.keys(this._eventMap).length === 0) {
-      delete this._eventMap;
-    }
-    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) {
-  // 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;
-  }
-
-  var navigator = window.navigator;
-
-
-  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 a=crypto lines into
-//   https://rawgit.com/aboba/edgertc/master/msortc-rs4.html#dictionary-rtcsrtpsdesparameters-members
-SDPUtils.parseCryptoLine = function(line) {
-  var parts = line.substr(9).split(' ');
-  return {
-    tag: parseInt(parts[0], 10),
-    cryptoSuite: parts[1],
-    keyParams: parts[2],
-    sessionParams: parts.slice(3),
-  };
-};
-
-SDPUtils.writeCryptoLine = function(parameters) {
-  return 'a=crypto:' + parameters.tag + ' ' +
-    parameters.cryptoSuite + ' ' +
-    (typeof parameters.keyParams === 'object'
-      ? SDPUtils.writeCryptoKeyParams(parameters.keyParams)
-      : parameters.keyParams) +
-    (parameters.sessionParams ? ' ' + parameters.sessionParams.join(' ') : '') +
-    '\r\n';
-};
-
-// Parses the crypto key parameters into
-//   https://rawgit.com/aboba/edgertc/master/msortc-rs4.html#rtcsrtpkeyparam*
-SDPUtils.parseCryptoKeyParams = function(keyParams) {
-  if (keyParams.indexOf('inline:') !== 0) {
-    return null;
-  }
-  var parts = keyParams.substr(7).split('|');
-  return {
-    keyMethod: 'inline',
-    keySalt: parts[0],
-    lifeTime: parts[1],
-    mkiValue: parts[2] ? parts[2].split(':')[0] : undefined,
-    mkiLength: parts[2] ? parts[2].split(':')[1] : undefined,
-  };
-};
-
-SDPUtils.writeCryptoKeyParams = function(keyParams) {
-  return keyParams.keyMethod + ':'
-    + keyParams.keySalt +
-    (keyParams.lifeTime ? '|' + keyParams.lifeTime : '') +
-    (keyParams.mkiValue && keyParams.mkiLength
-      ? '|' + keyParams.mkiValue + ':' + keyParams.mkiLength
-      : '');
-};
-
-// Extracts all SDES paramters.
-SDPUtils.getCryptoParameters = function(mediaSection, sessionpart) {
-  var lines = SDPUtils.matchPrefix(mediaSection + sessionpart,
-    'a=crypto:');
-  return lines.map(SDPUtils.parseCryptoLine);
-};
-
-// 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 ufrag = SDPUtils.matchPrefix(mediaSection + sessionpart,
-    'a=ice-ufrag:')[0];
-  var pwd = SDPUtils.matchPrefix(mediaSection + sessionpart,
-    'a=ice-pwd:')[0];
-  if (!(ufrag && pwd)) {
-    return null;
-  }
-  return {
-    usernameFragment: ufrag.substr(12),
-    password: pwd.substr(10),
-  };
-};
-
-// 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)
-});