text: (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 e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[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 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) {
          // 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;
      }
      
      // 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;
      }
      
      
      // 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);
        var e = new Event('addtrack'); // TODO: MediaStreamTrackEvent
        e.track = track;
        stream.dispatchEvent(e);
      }
      
      function removeTrackFromStreamAndFireEvent(track, stream) {
        stream.removeTrack(track);
        var e = new Event('removetrack'); // TODO: MediaStreamTrackEvent
        e.track = track;
        stream.dispatchEvent(e);
      }
      
      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);
        });
      }
      
      function makeError(name, description) {
        var e = new Error(description);
        e.name = name;
        return e;
      }
      
      module.exports = function(window, edgeVersion) {
        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.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 = 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;
        };
      
        // 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.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.
        // (whih is not yet the same as the WebRTC 1.0 transceiver)
        RTCPeerConnection.prototype._createTransceiver = function(kind) {
          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;
          }
          this.transceivers.push(transceiver);
          return transceiver;
        };
      
        RTCPeerConnection.prototype.addTrack = function(track, stream) {
          var alreadyExists = this.transceivers.find(function(s) {
            return s.track === track;
          });
      
          if (alreadyExists) {
            throw makeError('InvalidAccessError', 'Track already exists.');
          }
      
          if (this.signalingState === 'closed') {
            throw makeError('InvalidStateError',
                'Attempted to call addTrack on a closed peerconnection.');
          }
      
          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 (!(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].candidates = [];
          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].candidates !== null) {
              pc.transceivers[sdpMLineIndex].candidates.push(event.candidate);
            }
          };
          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 candidates = this.transceivers[sdpMLineIndex].candidates;
          this.transceivers[sdpMLineIndex].candidates = 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;
              event.candidate.candidate = SDPUtils.writeCandidate(cand);
            }
      
            // update local description.
            var sections = SDPUtils.splitSections(pc.localDescription.sdp);
            if (!end) {
              sections[event.candidate.sdpMLineIndex + 1] +=
                  'a=' + event.candidate.candidate + '\r\n';
            } else {
              sections[event.candidate.sdpMLineIndex + 1] +=
                  'a=end-of-candidates\r\n';
            }
            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() {
            candidates.forEach(function(candidate) {
              var e = new Event('RTCIceGatherEvent');
              e.candidate = candidate;
              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._updateConnectionState();
          };
      
          var dtlsTransport = new window.RTCDtlsTransport(iceTransport);
          dtlsTransport.ondtlsstatechange = function() {
            pc._updateConnectionState();
          };
          dtlsTransport.onerror = function() {
            // onerror does not set state to failed by itpc.
            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;
            }
            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;
      
          if (!isActionAllowedInSignalingState('setLocalDescription',
              description.type, this.signalingState) || this._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;
            });
      
            this.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.isDatachannel) {
                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);
              }
            });
          }
      
          this.localDescription = {
            type: description.type,
            sdp: description.sdp
          };
          switch (description.type) {
            case 'offer':
              this._updateSignalingState('have-local-offer');
              break;
            case 'answer':
              this._updateSignalingState('stable');
              break;
            default:
              throw new TypeError('unsupported type "' + description.type +
                  '"');
          }
      
          return Promise.resolve();
        };
      
        RTCPeerConnection.prototype.setRemoteDescription = function(description) {
          var pc = this;
      
          if (!isActionAllowedInSignalingState('setRemoteDescription',
              description.type, this.signalingState) || this._isClosed) {
            return Promise.reject(makeError('InvalidStateError',
                'Can not set remote ' + description.type +
                ' in state ' + pc.signalingState));
          }
      
          var streams = {};
          this.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;
          this.usingBundle = usingBundle;
          var iceOptions = SDPUtils.matchPrefix(sessionpart,
              'a=ice-options:')[0];
          if (iceOptions) {
            this.canTrickleIceCandidates = iceOptions.substr(14).split(' ')
                .indexOf('trickle') >= 0;
          } else {
            this.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 (kind === 'application' && protocol === 'DTLS/SCTP') {
              pc.transceivers[sdpMLineIndex] = {
                mid: mid,
                isDatachannel: true
              };
              return;
            }
      
            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);
                }
              }
      
              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 (this._dtlsRole === undefined) {
            this._dtlsRole = description.type === 'offer' ? 'active' : 'passive';
          }
      
          this.remoteDescription = {
            type: description.type,
            sdp: description.sdp
          };
          switch (description.type) {
            case 'offer':
              this._updateSignalingState('have-remote-offer');
              break;
            case 'answer':
              this._updateSignalingState('stable');
              break;
            default:
              throw new TypeError('unsupported type "' + description.type +
                  '"');
          }
          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 === false) {
              return;
            }
            pc.needNegotiation = false;
            var event = new Event('negotiationneeded');
            pc._dispatchEvent('negotiationneeded', event);
          }, 0);
        };
      
        // Update the connection state.
        RTCPeerConnection.prototype._updateConnectionState = function() {
          var newState;
          var states = {
            'new': 0,
            closed: 0,
            connecting: 0,
            checking: 0,
            connected: 0,
            completed: 0,
            disconnected: 0,
            failed: 0
          };
          this.transceivers.forEach(function(transceiver) {
            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 || states.checking > 0) {
            newState = 'connecting';
          } else if (states.disconnected > 0) {
            newState = 'disconnected';
          } else if (states.new > 0) {
            newState = 'new';
          } else if (states.connected > 0 || states.completed > 0) {
            newState = 'connected';
          }
      
          if (newState !== this.iceConnectionState) {
            this.iceConnectionState = newState;
            var event = new Event('iceconnectionstatechange');
            this._dispatchEvent('iceconnectionstatechange', event);
          }
        };
      
        RTCPeerConnection.prototype.createOffer = function() {
          var pc = this;
      
          if (this._isClosed) {
            return Promise.reject(makeError('InvalidStateError',
                'Can not call createOffer after close'));
          }
      
          var numAudioTracks = this.transceivers.filter(function(t) {
            return t.kind === 'audio';
          }).length;
          var numVideoTracks = this.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;
              }
            }
          }
      
          this.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) {
              this._createTransceiver('audio');
              numAudioTracks--;
            }
            if (numVideoTracks > 0) {
              this._createTransceiver('video');
              numVideoTracks--;
            }
          }
      
          var sdp = SDPUtils.writeSessionBoilerplate(this._sdpSessionId,
              this._sdpSessionVersion++);
          this.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 = 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';
              }
            });
      
            // 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 (this._config.bundlePolicy !== 'max-compat') {
            sdp += 'a=group:BUNDLE ' + this.transceivers.map(function(t) {
              return t.mid;
            }).join(' ') + '\r\n';
          }
          sdp += 'a=ice-options:trickle\r\n';
      
          this.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 (this._isClosed) {
            return Promise.reject(makeError('InvalidStateError',
                'Can not call createAnswer after close'));
          }
      
          var sdp = SDPUtils.writeSessionBoilerplate(this._sdpSessionId,
              this._sdpSessionVersion++);
          if (this.usingBundle) {
            sdp += 'a=group:BUNDLE ' + this.transceivers.map(function(t) {
              return t.mid;
            }).join(' ') + '\r\n';
          }
          var mediaSectionsInOffer = SDPUtils.splitSections(
              this.remoteDescription.sdp).length - 1;
          this.transceivers.forEach(function(transceiver, sdpMLineIndex) {
            if (sdpMLineIndex + 1 > mediaSectionsInOffer) {
              return;
            }
            if (transceiver.isDatachannel) {
              sdp += 'm=application 0 DTLS/SCTP 5000\r\n' +
                  'c=IN IP4 0.0.0.0\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 sections;
          if (!candidate || candidate.candidate === '') {
            for (var j = 0; j < this.transceivers.length; j++) {
              if (this.transceivers[j].isDatachannel) {
                continue;
              }
              this.transceivers[j].iceTransport.addRemoteCandidate({});
              sections = SDPUtils.splitSections(this.remoteDescription.sdp);
              sections[j + 1] += 'a=end-of-candidates\r\n';
              this.remoteDescription.sdp = sections.join('');
              if (this.usingBundle) {
                break;
              }
            }
          } else if (!(candidate.sdpMLineIndex !== undefined || candidate.sdpMid)) {
            throw new TypeError('sdpMLineIndex or sdpMid required');
          } else if (!this.remoteDescription) {
            return Promise.reject(makeError('InvalidStateError',
                'Can not add ICE candidate without a remote description'));
          } else {
            var sdpMLineIndex = candidate.sdpMLineIndex;
            if (candidate.sdpMid) {
              for (var i = 0; i < this.transceivers.length; i++) {
                if (this.transceivers[i].mid === candidate.sdpMid) {
                  sdpMLineIndex = i;
                  break;
                }
              }
            }
            var transceiver = this.transceivers[sdpMLineIndex];
            if (transceiver) {
              if (transceiver.isDatachannel) {
                return Promise.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 Promise.resolve();
              }
              // Ignore RTCP candidates, we assume RTCP-MUX.
              if (cand.component && cand.component !== 1) {
                return Promise.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 !== this.transceivers[0].iceTransport)) {
                if (!maybeAddCandidate(transceiver.iceTransport, cand)) {
                  return Promise.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.splitSections(this.remoteDescription.sdp);
              sections[sdpMLineIndex + 1] += 'a=' +
                  (cand.type ? candidateString : 'end-of-candidates')
                  + '\r\n';
              this.remoteDescription.sdp = sections.join('');
            } else {
              return Promise.reject(makeError('OperationError',
                  'Can not add ICE candidate'));
            }
          }
          return Promise.resolve();
        };
      
        RTCPeerConnection.prototype.getStats = function() {
          var promises = [];
          this.transceivers.forEach(function(transceiver) {
            ['rtpSender', 'rtpReceiver', 'iceGatherer', 'iceTransport',
                'dtlsTransport'].forEach(function(method) {
                  if (transceiver[method]) {
                    promises.push(transceiver[method].getStats());
                  }
                });
          });
          var fixStatsType = function(stat) {
            return {
              inboundrtp: 'inbound-rtp',
              outboundrtp: 'outbound-rtp',
              candidatepair: 'candidate-pair',
              localcandidate: 'local-candidate',
              remotecandidate: 'remote-candidate'
            }[stat.type] || stat.type;
          };
          return new Promise(function(resolve) {
            // shim getStats with maplike support
            var results = new Map();
            Promise.all(promises).then(function(res) {
              res.forEach(function(result) {
                Object.keys(result).forEach(function(id) {
                  result[id].type = fixStatsType(result[id]);
                  results.set(id, result[id]);
                });
              });
              resolve(results);
            });
          });
        };
      
        // 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":2}],2:[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 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],
          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.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); // was: relAddr
          sdp.push('rport');
          sdp.push(candidate.relatedPort); // was: relPort
        }
        if (candidate.tcpType && candidate.protocol.toLowerCase() === 'tcp') {
          sdp.push('tcptype');
          sdp.push(candidate.tcpType);
        }
        if (candidate.ufrag) {
          sdp.push('ufrag');
          sdp.push(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
        // was: channels
        parsed.numChannels = parts.length === 3 ? parseInt(parts[2], 10) : 1;
        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;
        }
        return 'a=rtpmap:' + pt + ' ' + codec.name + '/' + codec.clockRate +
            (codec.numChannels !== 1 ? '/' + codec.numChannels : '') + '\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) {
            params.push(param + '=' + codec.parameters[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;
      };
      
      // Extracts the MID (RFC 5888) from a media section.
      // returns the MID or undefined if no mid line was found.
      SDPUtils.getMid = function(mediaSection) {
        var mid = SDPUtils.matchPrefix(mediaSection, 'a=mid:')[0];
        if (mid) {
          return mid.substr(6);
        }
      }
      
      SDPUtils.parseFingerprint = function(line) {
        var parts = line.substr(14).split(' ');
        return {
          algorithm: parts[0].toLowerCase(), // algorithm is case-sensitive in Edge.
          value: parts[1]
        };
      };
      
      // Extracts DTLS parameters from SDP media section or sessionpart.
      // FIXME: for consistency with other functions this should only
      //   get the fingerprint line as input. See also getIceParameters.
      SDPUtils.getDtlsParameters = function(mediaSection, sessionpart) {
        var lines = SDPUtils.matchPrefix(mediaSection + sessionpart,
            'a=fingerprint:');
        // Note: a=setup line is ignored since we use the 'auto' role.
        // Note2: 'algorithm' is not case sensitive except in Edge.
        return {
          role: 'auto',
          fingerprints: lines.map(SDPUtils.parseFingerprint)
        };
      };
      
      // Serializes DTLS parameters to SDP.
      SDPUtils.writeDtlsParameters = function(params, setupType) {
        var sdp = 'a=setup:' + setupType + '\r\n';
        params.fingerprints.forEach(function(fp) {
          sdp += 'a=fingerprint:' + fp.algorithm + ' ' + fp.value + '\r\n';
        });
        return sdp;
      };
      // Parses ICE information from SDP media section or sessionpart.
      // FIXME: for consistency with other functions this should only
      //   get the ice-ufrag and ice-pwd lines as input.
      SDPUtils.getIceParameters = function(mediaSection, sessionpart) {
        var lines = SDPUtils.splitLines(mediaSection);
        // Search in session part, too.
        lines = lines.concat(SDPUtils.splitLines(sessionpart));
        var iceParameters = {
          usernameFragment: lines.filter(function(line) {
            return line.indexOf('a=ice-ufrag:') === 0;
          })[0].substr(12),
          password: lines.filter(function(line) {
            return line.indexOf('a=ice-pwd:') === 0;
          })[0].substr(10)
        };
        return iceParameters;
      };
      
      // Serializes ICE parameters to SDP.
      SDPUtils.writeIceParameters = function(params) {
        return 'a=ice-ufrag:' + params.usernameFragment + '\r\n' +
            'a=ice-pwd:' + params.password + '\r\n';
      };
      
      // Parses the SDP media section and returns RTCRtpParameters.
      SDPUtils.parseRtpParameters = function(mediaSection) {
        var description = {
          codecs: [],
          headerExtensions: [],
          fecMechanisms: [],
          rtcp: []
        };
        var lines = SDPUtils.splitLines(mediaSection);
        var mline = lines[0].split(' ');
        for (var i = 3; i < mline.length; i++) { // find all codecs from mline[3..]
          var pt = mline[i];
          var rtpmapline = SDPUtils.matchPrefix(
              mediaSection, 'a=rtpmap:' + pt + ' ')[0];
          if (rtpmapline) {
            var codec = SDPUtils.parseRtpMap(rtpmapline);
            var fmtps = SDPUtils.matchPrefix(
                mediaSection, 'a=fmtp:' + pt + ' ');
            // Only the first a=fmtp:<pt> is considered.
            codec.parameters = fmtps.length ? SDPUtils.parseFmtp(fmtps[0]) : {};
            codec.rtcpFeedback = SDPUtils.matchPrefix(
                mediaSection, 'a=rtcp-fb:' + pt + ' ')
              .map(SDPUtils.parseRtcpFb);
            description.codecs.push(codec);
            // parse FEC mechanisms from rtpmap lines.
            switch (codec.name.toUpperCase()) {
              case 'RED':
              case 'ULPFEC':
                description.fecMechanisms.push(codec.name.toUpperCase());
                break;
              default: // only RED and ULPFEC are recognized as FEC mechanisms.
                break;
            }
          }
        }
        SDPUtils.matchPrefix(mediaSection, 'a=extmap:').forEach(function(line) {
          description.headerExtensions.push(SDPUtils.parseExtmap(line));
        });
        // FIXME: parse rtcp.
        return description;
      };
      
      // Generates parts of the SDP media section describing the capabilities /
      // parameters.
      SDPUtils.writeRtpDescription = function(kind, caps) {
        var sdp = '';
      
        // Build the mline.
        sdp += 'm=' + kind + ' ';
        sdp += caps.codecs.length > 0 ? '9' : '0'; // reject if no codecs.
        sdp += ' UDP/TLS/RTP/SAVPF ';
        sdp += caps.codecs.map(function(codec) {
          if (codec.preferredPayloadType !== undefined) {
            return codec.preferredPayloadType;
          }
          return codec.payloadType;
        }).join(' ') + '\r\n';
      
        sdp += 'c=IN IP4 0.0.0.0\r\n';
        sdp += 'a=rtcp:9 IN IP4 0.0.0.0\r\n';
      
        // Add a=rtpmap lines for each codec. Also fmtp and rtcp-fb.
        caps.codecs.forEach(function(codec) {
          sdp += SDPUtils.writeRtpMap(codec);
          sdp += SDPUtils.writeFmtp(codec);
          sdp += SDPUtils.writeRtcpFb(codec);
        });
        var maxptime = 0;
        caps.codecs.forEach(function(codec) {
          if (codec.maxptime > maxptime) {
            maxptime = codec.maxptime;
          }
        });
        if (maxptime > 0) {
          sdp += 'a=maxptime:' + maxptime + '\r\n';
        }
        sdp += 'a=rtcp-mux\r\n';
      
        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.split(' ');
          parts.shift();
          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),
              rtx: {
                ssrc: secondarySsrc
              }
            };
            encodingParameters.push(encParam);
            if (hasRed) {
              encParam = JSON.parse(JSON.stringify(encParam));
              encParam.fec = {
                ssrc: secondarySsrc,
                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 = {};
      
        var cname;
        // Gets the first SSRC. Note that 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(parts) {
          return parts.attribute === 'msid';
        });
        if (planB.length > 0) {
          parts = planB[0].value.split(' ');
          return {stream: parts[0], track: parts[1]};
        }
      };
      
      // 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
      SDPUtils.writeSessionBoilerplate = function(sessId, sessVer) {
        var sessionId;
        var version = sessVer !== undefined ? sessVer : 2;
        if (sessId) {
          sessionId = sessId;
        } else {
          sessionId = SDPUtils.generateSessionId();
        }
        // FIXME: sess-id should be an NTP timestamp.
        return 'v=0\r\n' +
            'o=thisisadapterortc ' + 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 mline = lines[0].split(' ');
        return {
          kind: mline[0].substr(2),
          port: parseInt(mline[1], 10),
          protocol: mline[2],
          fmt: mline.slice(3).join(' ')
        };
      };
      
      // Expose public methods.
      if (typeof module === 'object') {
        module.exports = SDPUtils;
      }
      
      },{}],3:[function(require,module,exports){
      (function (global){
      /*
       *  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 adapterFactory = require('./adapter_factory.js');
      module.exports = adapterFactory({window: global.window});
      
      }).call(this,typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
      },{"./adapter_factory.js":4}],4:[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 utils = require('./utils');
      // Shimming starts here.
      module.exports = function(dependencies, opts) {
        var window = dependencies && dependencies.window;
      
        var options = {
          shimChrome: true,
          shimFirefox: true,
          shimEdge: true,
          shimSafari: true,
        };
      
        for (var key in opts) {
          if (hasOwnProperty.call(opts, key)) {
            options[key] = opts[key];
          }
        }
      
        // Utils.
        var logging = utils.log;
        var browserDetails = utils.detectBrowser(window);
      
        // Uncomment the line below if you want logging to occur, including logging
        // for the switch statement below. Can also be turned on in the browser via
        // adapter.disableLog(false), but then logging from the switch statement below
        // will not appear.
        // require('./utils').disableLog(false);
      
        // Browser shims.
        var chromeShim = require('./chrome/chrome_shim') || null;
        var edgeShim = require('./edge/edge_shim') || null;
        var firefoxShim = require('./firefox/firefox_shim') || null;
        var safariShim = require('./safari/safari_shim') || null;
        var commonShim = require('./common_shim') || null;
      
        // Export to the adapter global object visible in the browser.
        var adapter = {
          browserDetails: browserDetails,
          commonShim: commonShim,
          extractVersion: utils.extractVersion,
          disableLog: utils.disableLog,
          disableWarnings: utils.disableWarnings
        };
      
        // Shim browser if found.
        switch (browserDetails.browser) {
          case 'chrome':
            if (!chromeShim || !chromeShim.shimPeerConnection ||
                !options.shimChrome) {
              logging('Chrome shim is not included in this adapter release.');
              return adapter;
            }
            logging('adapter.js shimming chrome.');
            // Export to the adapter global object visible in the browser.
            adapter.browserShim = chromeShim;
            commonShim.shimCreateObjectURL(window);
      
            chromeShim.shimGetUserMedia(window);
            chromeShim.shimMediaStream(window);
            chromeShim.shimSourceObject(window);
            chromeShim.shimPeerConnection(window);
            chromeShim.shimOnTrack(window);
            chromeShim.shimAddTrackRemoveTrack(window);
            chromeShim.shimGetSendersWithDtmf(window);
      
            commonShim.shimRTCIceCandidate(window);
            commonShim.shimMaxMessageSize(window);
            commonShim.shimSendThrowTypeError(window);
            break;
          case 'firefox':
            if (!firefoxShim || !firefoxShim.shimPeerConnection ||
                !options.shimFirefox) {
              logging('Firefox shim is not included in this adapter release.');
              return adapter;
            }
            logging('adapter.js shimming firefox.');
            // Export to the adapter global object visible in the browser.
            adapter.browserShim = firefoxShim;
            commonShim.shimCreateObjectURL(window);
      
            firefoxShim.shimGetUserMedia(window);
            firefoxShim.shimSourceObject(window);
            firefoxShim.shimPeerConnection(window);
            firefoxShim.shimOnTrack(window);
            firefoxShim.shimRemoveStream(window);
      
            commonShim.shimRTCIceCandidate(window);
            commonShim.shimMaxMessageSize(window);
            commonShim.shimSendThrowTypeError(window);
            break;
          case 'edge':
            if (!edgeShim || !edgeShim.shimPeerConnection || !options.shimEdge) {
              logging('MS edge shim is not included in this adapter release.');
              return adapter;
            }
            logging('adapter.js shimming edge.');
            // Export to the adapter global object visible in the browser.
            adapter.browserShim = edgeShim;
            commonShim.shimCreateObjectURL(window);
      
            edgeShim.shimGetUserMedia(window);
            edgeShim.shimPeerConnection(window);
            edgeShim.shimReplaceTrack(window);
      
            // the edge shim implements the full RTCIceCandidate object.
      
            commonShim.shimMaxMessageSize(window);
            commonShim.shimSendThrowTypeError(window);
            break;
          case 'safari':
            if (!safariShim || !options.shimSafari) {
              logging('Safari shim is not included in this adapter release.');
              return adapter;
            }
            logging('adapter.js shimming safari.');
            // Export to the adapter global object visible in the browser.
            adapter.browserShim = safariShim;
            commonShim.shimCreateObjectURL(window);
      
            safariShim.shimRTCIceServerUrls(window);
            safariShim.shimCallbacksAPI(window);
            safariShim.shimLocalStreamsAPI(window);
            safariShim.shimRemoteStreamsAPI(window);
            safariShim.shimTrackEventTransceiver(window);
            safariShim.shimGetUserMedia(window);
            safariShim.shimCreateOfferLegacy(window);
      
            commonShim.shimRTCIceCandidate(window);
            commonShim.shimMaxMessageSize(window);
            commonShim.shimSendThrowTypeError(window);
            break;
          default:
            logging('Unsupported browser!');
            break;
        }
      
        return adapter;
      };
      
      },{"./chrome/chrome_shim":5,"./common_shim":7,"./edge/edge_shim":8,"./firefox/firefox_shim":10,"./safari/safari_shim":12,"./utils":13}],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';
      var utils = require('../utils.js');
      var logging = utils.log;
      
      module.exports = {
        shimGetUserMedia: require('./getusermedia'),
        shimMediaStream: function(window) {
          window.MediaStream = window.MediaStream || window.webkitMediaStream;
        },
      
        shimOnTrack: function(window) {
          if (typeof window === 'object' && window.RTCPeerConnection && !('ontrack' in
              window.RTCPeerConnection.prototype)) {
            Object.defineProperty(window.RTCPeerConnection.prototype, 'ontrack', {
              get: function() {
                return this._ontrack;
              },
              set: function(f) {
                if (this._ontrack) {
                  this.removeEventListener('track', this._ontrack);
                }
                this.addEventListener('track', this._ontrack = f);
              }
            });
            var origSetRemoteDescription =
                window.RTCPeerConnection.prototype.setRemoteDescription;
            window.RTCPeerConnection.prototype.setRemoteDescription = function() {
              var pc = this;
              if (!pc._ontrackpoly) {
                pc._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;
                    if (window.RTCPeerConnection.prototype.getReceivers) {
                      receiver = pc.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];
                    pc.dispatchEvent(event);
                  });
                  e.stream.getTracks().forEach(function(track) {
                    var receiver;
                    if (window.RTCPeerConnection.prototype.getReceivers) {
                      receiver = pc.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];
                    pc.dispatchEvent(event);
                  });
                };
                pc.addEventListener('addstream', pc._ontrackpoly);
              }
              return origSetRemoteDescription.apply(pc, arguments);
            };
          } else if (!('RTCRtpTransceiver' in window)) {
            utils.wrapPeerConnectionEvent(window, 'track', function(e) {
              if (!e.transceiver) {
                e.transceiver = {receiver: e.receiver};
              }
              return e;
            });
          }
        },
      
        shimGetSendersWithDtmf: function(window) {
          // Overrides addTrack/removeTrack, depends on shimAddTrackRemoveTrack.
          if (typeof window === 'object' && window.RTCPeerConnection &&
              !('getSenders' in window.RTCPeerConnection.prototype) &&
              'createDTMFSender' in window.RTCPeerConnection.prototype) {
            var shimSenderWithDtmf = function(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() {
                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(track, stream) {
                var pc = this;
                var sender = origAddTrack.apply(pc, arguments);
                if (!sender) {
                  sender = shimSenderWithDtmf(pc, track);
                  pc._senders.push(sender);
                }
                return sender;
              };
      
              var origRemoveTrack = window.RTCPeerConnection.prototype.removeTrack;
              window.RTCPeerConnection.prototype.removeTrack = function(sender) {
                var pc = this;
                origRemoveTrack.apply(pc, arguments);
                var idx = pc._senders.indexOf(sender);
                if (idx !== -1) {
                  pc._senders.splice(idx, 1);
                }
              };
            }
            var origAddStream = window.RTCPeerConnection.prototype.addStream;
            window.RTCPeerConnection.prototype.addStream = function(stream) {
              var pc = this;
              pc._senders = pc._senders || [];
              origAddStream.apply(pc, [stream]);
              stream.getTracks().forEach(function(track) {
                pc._senders.push(shimSenderWithDtmf(pc, track));
              });
            };
      
            var origRemoveStream = window.RTCPeerConnection.prototype.removeStream;
            window.RTCPeerConnection.prototype.removeStream = function(stream) {
              var pc = this;
              pc._senders = pc._senders || [];
              origRemoveStream.apply(pc, [stream]);
      
              stream.getTracks().forEach(function(track) {
                var sender = pc._senders.find(function(s) {
                  return s.track === track;
                });
                if (sender) {
                  pc._senders.splice(pc._senders.indexOf(sender), 1); // remove sender
                }
              });
            };
          } else if (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() {
              var pc = this;
              var senders = origGetSenders.apply(pc, []);
              senders.forEach(function(sender) {
                sender._pc = pc;
              });
              return senders;
            };
      
            Object.defineProperty(window.RTCRtpSender.prototype, 'dtmf', {
              get: function() {
                if (this._dtmf === undefined) {
                  if (this.track.kind === 'audio') {
                    this._dtmf = this._pc.createDTMFSender(this.track);
                  } else {
                    this._dtmf = null;
                  }
                }
                return this._dtmf;
              }
            });
          }
        },
      
        shimSourceObject: function(window) {
          var URL = window && window.URL;
      
          if (typeof window === 'object') {
            if (window.HTMLMediaElement &&
              !('srcObject' in window.HTMLMediaElement.prototype)) {
              // Shim the srcObject property, once, when HTMLMediaElement is found.
              Object.defineProperty(window.HTMLMediaElement.prototype, 'srcObject', {
                get: function() {
                  return this._srcObject;
                },
                set: function(stream) {
                  var self = this;
                  // Use _srcObject as a private property for this shim
                  this._srcObject = stream;
                  if (this.src) {
                    URL.revokeObjectURL(this.src);
                  }
      
                  if (!stream) {
                    this.src = '';
                    return undefined;
                  }
                  this.src = URL.createObjectURL(stream);
                  // We need to recreate the blob url when a track is added or
                  // removed. Doing it manually since we want to avoid a recursion.
                  stream.addEventListener('addtrack', function() {
                    if (self.src) {
                      URL.revokeObjectURL(self.src);
                    }
                    self.src = URL.createObjectURL(stream);
                  });
                  stream.addEventListener('removetrack', function() {
                    if (self.src) {
                      URL.revokeObjectURL(self.src);
                    }
                    self.src = URL.createObjectURL(stream);
                  });
                }
              });
            }
          }
        },
      
        shimAddTrackRemoveTrackWithNative: function(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() {
            var pc = this;
            this._shimmedLocalStreams = this._shimmedLocalStreams || {};
            return Object.keys(this._shimmedLocalStreams).map(function(streamId) {
              return pc._shimmedLocalStreams[streamId][0];
            });
          };
      
          var origAddTrack = window.RTCPeerConnection.prototype.addTrack;
          window.RTCPeerConnection.prototype.addTrack = function(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(stream) {
            var pc = this;
            this._shimmedLocalStreams = this._shimmedLocalStreams || {};
      
            stream.getTracks().forEach(function(track) {
              var alreadyExists = pc.getSenders().find(function(s) {
                return s.track === track;
              });
              if (alreadyExists) {
                throw new DOMException('Track already exists.',
                    'InvalidAccessError');
              }
            });
            var existingSenders = pc.getSenders();
            origAddStream.apply(this, arguments);
            var newSenders = pc.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(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(sender) {
            var pc = this;
            this._shimmedLocalStreams = this._shimmedLocalStreams || {};
            if (sender) {
              Object.keys(this._shimmedLocalStreams).forEach(function(streamId) {
                var idx = pc._shimmedLocalStreams[streamId].indexOf(sender);
                if (idx !== -1) {
                  pc._shimmedLocalStreams[streamId].splice(idx, 1);
                }
                if (pc._shimmedLocalStreams[streamId].length === 1) {
                  delete pc._shimmedLocalStreams[streamId];
                }
              });
            }
            return origRemoveTrack.apply(this, arguments);
          };
        },
      
        shimAddTrackRemoveTrack: function(window) {
          var browserDetails = utils.detectBrowser(window);
          // shim addTrack and removeTrack.
          if (window.RTCPeerConnection.prototype.addTrack &&
              browserDetails.version >= 65) {
            return this.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() {
            var pc = this;
            var nativeStreams = origGetLocalStreams.apply(this);
            pc._reverseStreams = pc._reverseStreams || {};
            return nativeStreams.map(function(stream) {
              return pc._reverseStreams[stream.id];
            });
          };
      
          var origAddStream = window.RTCPeerConnection.prototype.addStream;
          window.RTCPeerConnection.prototype.addStream = function(stream) {
            var pc = this;
            pc._streams = pc._streams || {};
            pc._reverseStreams = pc._reverseStreams || {};
      
            stream.getTracks().forEach(function(track) {
              var alreadyExists = pc.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 (!pc._reverseStreams[stream.id]) {
              var newStream = new window.MediaStream(stream.getTracks());
              pc._streams[stream.id] = newStream;
              pc._reverseStreams[newStream.id] = stream;
              stream = newStream;
            }
            origAddStream.apply(pc, [stream]);
          };
      
          var origRemoveStream = window.RTCPeerConnection.prototype.removeStream;
          window.RTCPeerConnection.prototype.removeStream = function(stream) {
            var pc = this;
            pc._streams = pc._streams || {};
            pc._reverseStreams = pc._reverseStreams || {};
      
            origRemoveStream.apply(pc, [(pc._streams[stream.id] || stream)]);
            delete pc._reverseStreams[(pc._streams[stream.id] ?
                pc._streams[stream.id].id : stream.id)];
            delete pc._streams[stream.id];
          };
      
          window.RTCPeerConnection.prototype.addTrack = function(track, stream) {
            var pc = this;
            if (pc.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 = pc.getSenders().find(function(s) {
              return s.track === track;
            });
            if (alreadyExists) {
              throw new DOMException('Track already exists.',
                  'InvalidAccessError');
            }
      
            pc._streams = pc._streams || {};
            pc._reverseStreams = pc._reverseStreams || {};
            var oldStream = pc._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() {
                pc.dispatchEvent(new Event('negotiationneeded'));
              });
            } else {
              var newStream = new window.MediaStream([track]);
              pc._streams[stream.id] = newStream;
              pc._reverseStreams[newStream.id] = stream;
              pc.addStream(newStream);
            }
            return pc.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];
            window.RTCPeerConnection.prototype[method] = function() {
              var pc = this;
              var args = arguments;
              var isLegacyCall = arguments.length &&
                  typeof arguments[0] === 'function';
              if (isLegacyCall) {
                return nativeMethod.apply(pc, [
                  function(description) {
                    var desc = replaceInternalStreamId(pc, description);
                    args[0].apply(null, [desc]);
                  },
                  function(err) {
                    if (args[1]) {
                      args[1].apply(null, err);
                    }
                  }, arguments[2]
                ]);
              }
              return nativeMethod.apply(pc, arguments)
              .then(function(description) {
                return replaceInternalStreamId(pc, description);
              });
            };
          });
      
          var origSetLocalDescription =
              window.RTCPeerConnection.prototype.setLocalDescription;
          window.RTCPeerConnection.prototype.setLocalDescription = function() {
            var pc = this;
            if (!arguments.length || !arguments[0].type) {
              return origSetLocalDescription.apply(pc, arguments);
            }
            arguments[0] = replaceExternalStreamId(pc, arguments[0]);
            return origSetLocalDescription.apply(pc, 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() {
                  var pc = this;
                  var description = origLocalDescription.get.apply(this);
                  if (description.type === '') {
                    return description;
                  }
                  return replaceInternalStreamId(pc, description);
                }
              });
      
          window.RTCPeerConnection.prototype.removeTrack = function(sender) {
            var pc = this;
            if (pc.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 === pc;
            if (!isLocal) {
              throw new DOMException('Sender was not created by this connection.',
                  'InvalidAccessError');
            }
      
            // Search for the native stream the senders track belongs to.
            pc._streams = pc._streams || {};
            var stream;
            Object.keys(pc._streams).forEach(function(streamid) {
              var hasTrack = pc._streams[streamid].getTracks().find(function(track) {
                return sender.track === track;
              });
              if (hasTrack) {
                stream = pc._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.
                pc.removeStream(pc._reverseStreams[stream.id]);
              } else {
                // relying on the same odd chrome behaviour as above.
                stream.removeTrack(sender.track);
              }
              pc.dispatchEvent(new Event('negotiationneeded'));
            }
          };
        },
      
        shimPeerConnection: function(window) {
          var browserDetails = utils.detectBrowser(window);
      
          // The RTCPeerConnection object.
          if (!window.RTCPeerConnection && window.webkitRTCPeerConnection) {
            window.RTCPeerConnection = function(pcConfig, pcConstraints) {
              // Translate iceTransportPolicy to iceTransports,
              // see https://code.google.com/p/webrtc/issues/detail?id=4869
              // this was fixed in M56 along with unprefixing RTCPeerConnection.
              logging('PeerConnection');
              if (pcConfig && pcConfig.iceTransportPolicy) {
                pcConfig.iceTransports = pcConfig.iceTransportPolicy;
              }
      
              return new window.webkitRTCPeerConnection(pcConfig, pcConstraints);
            };
            window.RTCPeerConnection.prototype =
                window.webkitRTCPeerConnection.prototype;
            // wrap static methods. Currently just generateCertificate.
            if (window.webkitRTCPeerConnection.generateCertificate) {
              Object.defineProperty(window.RTCPeerConnection, 'generateCertificate', {
                get: function() {
                  return window.webkitRTCPeerConnection.generateCertificate;
                }
              });
            }
          } else {
            // migrate from non-spec RTCIceServer.url to RTCIceServer.urls
            var OrigPeerConnection = window.RTCPeerConnection;
            window.RTCPeerConnection = function(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;
                    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.
            Object.defineProperty(window.RTCPeerConnection, 'generateCertificate', {
              get: function() {
                return OrigPeerConnection.generateCertificate;
              }
            });
          }
      
          var origGetStats = window.RTCPeerConnection.prototype.getStats;
          window.RTCPeerConnection.prototype.getStats = function(selector,
              successCallback, errorCallback) {
            var pc = this;
            var args = arguments;
      
            // 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 arguments[0] !== 'function')) {
              return origGetStats.apply(this, []);
            }
      
            var fixChromeStats_ = function(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(stats) {
              return new Map(Object.keys(stats).map(function(key) {
                return [key, stats[key]];
              }));
            };
      
            if (arguments.length >= 2) {
              var successCallbackWrapper_ = function(response) {
                args[1](makeMapStats(fixChromeStats_(response)));
              };
      
              return origGetStats.apply(this, [successCallbackWrapper_,
                arguments[0]]);
            }
      
            // promise-support
            return new Promise(function(resolve, reject) {
              origGetStats.apply(pc, [
                function(response) {
                  resolve(makeMapStats(fixChromeStats_(response)));
                }, reject]);
            }).then(successCallback, errorCallback);
          };
      
          // add promise support -- natively available in Chrome 51
          if (browserDetails.version < 51) {
            ['setLocalDescription', 'setRemoteDescription', 'addIceCandidate']
                .forEach(function(method) {
                  var nativeMethod = window.RTCPeerConnection.prototype[method];
                  window.RTCPeerConnection.prototype[method] = function() {
                    var args = arguments;
                    var pc = this;
                    var promise = new Promise(function(resolve, reject) {
                      nativeMethod.apply(pc, [args[0], resolve, reject]);
                    });
                    if (args.length < 2) {
                      return promise;
                    }
                    return promise.then(function() {
                      args[1].apply(null, []);
                    },
                    function(err) {
                      if (args.length >= 3) {
                        args[2].apply(null, [err]);
                      }
                    });
                  };
                });
          }
      
          // promise support for createOffer and createAnswer. Available (without
          // bugs) since M52: crbug/619289
          if (browserDetails.version < 52) {
            ['createOffer', 'createAnswer'].forEach(function(method) {
              var nativeMethod = window.RTCPeerConnection.prototype[method];
              window.RTCPeerConnection.prototype[method] = function() {
                var pc = this;
                if (arguments.length < 1 || (arguments.length === 1 &&
                    typeof arguments[0] === 'object')) {
                  var opts = arguments.length === 1 ? arguments[0] : undefined;
                  return new Promise(function(resolve, reject) {
                    nativeMethod.apply(pc, [resolve, reject, opts]);
                  });
                }
                return nativeMethod.apply(this, arguments);
              };
            });
          }
      
          // shim implicit creation of RTCSessionDescription/RTCIceCandidate
          ['setLocalDescription', 'setRemoteDescription', 'addIceCandidate']
              .forEach(function(method) {
                var nativeMethod = window.RTCPeerConnection.prototype[method];
                window.RTCPeerConnection.prototype[method] = function() {
                  arguments[0] = new ((method === 'addIceCandidate') ?
                      window.RTCIceCandidate :
                      window.RTCSessionDescription)(arguments[0]);
                  return nativeMethod.apply(this, arguments);
                };
              });
      
          // support for addIceCandidate(null or undefined)
          var nativeAddIceCandidate =
              window.RTCPeerConnection.prototype.addIceCandidate;
          window.RTCPeerConnection.prototype.addIceCandidate = function() {
            if (!arguments[0]) {
              if (arguments[1]) {
                arguments[1].apply(null);
              }
              return Promise.resolve();
            }
            return nativeAddIceCandidate.apply(this, arguments);
          };
        }
      };
      
      },{"../utils.js":13,"./getusermedia":6}],6:[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 utils = require('../utils.js');
      var logging = utils.log;
      
      // Expose public methods.
      module.exports = function(window) {
        var browserDetails = utils.detectBrowser(window);
        var navigator = window && window.navigator;
      
        var constraintsToChrome_ = function(c) {
          if (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(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(constraints, func) {
          if (browserDetails.version >= 61) {
            return func(constraints);
          }
          constraints = JSON.parse(JSON.stringify(constraints));
          if (constraints && typeof constraints.audio === 'object') {
            var remap = function(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 === '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;
              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().indexOf(match) !== -1;
                    });
                  });
                  if (!dev && devices.length && matches.indexOf('back') !== -1) {
                    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(e) {
          return {
            name: {
              PermissionDeniedError: 'NotAllowedError',
              InvalidStateError: 'NotReadableError',
              DevicesNotFoundError: 'NotFoundError',
              ConstraintNotSatisfiedError: 'OverconstrainedError',
              TrackStartError: 'NotReadableError',
              MediaDeviceFailedDueToShutdown: 'NotReadableError',
              MediaDeviceKillSwitchOn: 'NotReadableError'
            }[e.name] || e.name,
            message: e.message,
            constraint: e.constraintName,
            toString: function() {
              return this.name + (this.message && ': ') + this.message;
            }
          };
        };
      
        var getUserMedia_ = function(constraints, onSuccess, onError) {
          shimConstraints_(constraints, function(c) {
            navigator.webkitGetUserMedia(c, onSuccess, function(e) {
              if (onError) {
                onError(shimError_(e));
              }
            });
          });
        };
      
        navigator.getUserMedia = getUserMedia_;
      
        // Returns the result of getUserMedia as a Promise.
        var getUserMediaPromise_ = function(constraints) {
          return new Promise(function(resolve, reject) {
            navigator.getUserMedia(constraints, resolve, reject);
          });
        };
      
        if (!navigator.mediaDevices) {
          navigator.mediaDevices = {
            getUserMedia: getUserMediaPromise_,
            enumerateDevices: function() {
              return new Promise(function(resolve) {
                var kinds = {audio: 'audioinput', video: 'videoinput'};
                return window.MediaStreamTrack.getSources(function(devices) {
                  resolve(devices.map(function(device) {
                    return {label: device.label,
                      kind: kinds[device.kind],
                      deviceId: device.id,
                      groupId: ''};
                  }));
                });
              });
            },
            getSupportedConstraints: function() {
              return {
                deviceId: true, echoCancellation: true, facingMode: true,
                frameRate: true, height: true, width: true
              };
            }
          };
        }
      
        // A shim for getUserMedia method on the mediaDevices object.
        // TODO(KaptenJansson) remove once implemented in Chrome stable.
        if (!navigator.mediaDevices.getUserMedia) {
          navigator.mediaDevices.getUserMedia = function(constraints) {
            return getUserMediaPromise_(constraints);
          };
        } else {
          // Even though Chrome 45 has navigator.mediaDevices and a getUserMedia
          // function which returns a Promise, it does not accept spec-style
          // constraints.
          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));
              });
            });
          };
        }
      
        // Dummy devicechange event methods.
        // TODO(KaptenJansson) remove once implemented in Chrome stable.
        if (typeof navigator.mediaDevices.addEventListener === 'undefined') {
          navigator.mediaDevices.addEventListener = function() {
            logging('Dummy mediaDevices.addEventListener called.');
          };
        }
        if (typeof navigator.mediaDevices.removeEventListener === 'undefined') {
          navigator.mediaDevices.removeEventListener = function() {
            logging('Dummy mediaDevices.removeEventListener called.');
          };
        }
      };
      
      },{"../utils.js":13}],7:[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');
      var utils = require('./utils');
      
      module.exports = {
        shimRTCIceCandidate: function(window) {
          // foundation is arbitrarily chosen as an indicator for full support for
          // https://w3c.github.io/webrtc-pc/#rtcicecandidate-interface
          if (window.RTCIceCandidate && 'foundation' in
              window.RTCIceCandidate.prototype) {
            return;
          }
      
          var NativeRTCIceCandidate = window.RTCIceCandidate;
          window.RTCIceCandidate = function(args) {
            // Remove the a= which shouldn't be part of the candidate string.
            if (typeof args === 'object' && args.candidate &&
                args.candidate.indexOf('a=') === 0) {
              args = JSON.parse(JSON.stringify(args));
              args.candidate = args.candidate.substr(2);
            }
      
            // Augment the native candidate with the parsed fields.
            var nativeCandidate = new NativeRTCIceCandidate(args);
            var parsedCandidate = SDPUtils.parseCandidate(args.candidate);
            var augmentedCandidate = Object.assign(nativeCandidate,
                parsedCandidate);
      
            // Add a serializer that does not serialize the extra attributes.
            augmentedCandidate.toJSON = function() {
              return {
                candidate: augmentedCandidate.candidate,
                sdpMid: augmentedCandidate.sdpMid,
                sdpMLineIndex: augmentedCandidate.sdpMLineIndex,
                usernameFragment: augmentedCandidate.usernameFragment,
              };
            };
            return augmentedCandidate;
          };
      
          // 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;
          });
        },
      
        // shimCreateObjectURL must be called before shimSourceObject to avoid loop.
      
        shimCreateObjectURL: function(window) {
          var URL = window && window.URL;
      
          if (!(typeof window === 'object' && window.HTMLMediaElement &&
                'srcObject' in window.HTMLMediaElement.prototype &&
              URL.createObjectURL && URL.revokeObjectURL)) {
            // Only shim CreateObjectURL using srcObject if srcObject exists.
            return undefined;
          }
      
          var nativeCreateObjectURL = URL.createObjectURL.bind(URL);
          var nativeRevokeObjectURL = URL.revokeObjectURL.bind(URL);
          var streams = new Map(), newId = 0;
      
          URL.createObjectURL = function(stream) {
            if ('getTracks' in stream) {
              var url = 'polyblob:' + (++newId);
              streams.set(url, stream);
              utils.deprecated('URL.createObjectURL(stream)',
                  'elem.srcObject = stream');
              return url;
            }
            return nativeCreateObjectURL(stream);
          };
          URL.revokeObjectURL = function(url) {
            nativeRevokeObjectURL(url);
            streams.delete(url);
          };
      
          var dsc = Object.getOwnPropertyDescriptor(window.HTMLMediaElement.prototype,
                                                    'src');
          Object.defineProperty(window.HTMLMediaElement.prototype, 'src', {
            get: function() {
              return dsc.get.apply(this);
            },
            set: function(url) {
              this.srcObject = streams.get(url) || null;
              return dsc.set.apply(this, [url]);
            }
          });
      
          var nativeSetAttribute = window.HTMLMediaElement.prototype.setAttribute;
          window.HTMLMediaElement.prototype.setAttribute = function() {
            if (arguments.length === 2 &&
                ('' + arguments[0]).toLowerCase() === 'src') {
              this.srcObject = streams.get(arguments[1]) || null;
            }
            return nativeSetAttribute.apply(this, arguments);
          };
        },
      
        shimMaxMessageSize: function(window) {
          if (window.RTCSctpTransport || !window.RTCPeerConnection) {
            return;
          }
          var browserDetails = utils.detectBrowser(window);
      
          if (!('sctp' in window.RTCPeerConnection.prototype)) {
            Object.defineProperty(window.RTCPeerConnection.prototype, 'sctp', {
              get: function() {
                return typeof this._sctp === 'undefined' ? null : this._sctp;
              }
            });
          }
      
          var sctpInDescription = function(description) {
            var sections = SDPUtils.splitSections(description.sdp);
            sections.shift();
            return sections.some(function(mediaSection) {
              var mLine = SDPUtils.parseMLine(mediaSection);
              return mLine && mLine.kind === 'application'
                  && mLine.protocol.indexOf('SCTP') !== -1;
            });
          };
      
          var getRemoteFirefoxVersion = function(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(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 {
                // 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;
              }
            }
            return canSendMaxMessageSize;
          };
      
          var getMaxMessageSize = function(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 = SDPUtils.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() {
            var pc = this;
            pc._sctp = null;
      
            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;
              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() {
                  return maxMessageSize;
                }
              });
              pc._sctp = sctp;
            }
      
            return origSetRemoteDescription.apply(pc, arguments);
          };
        },
      
        shimSendThrowTypeError: function(window) {
          // 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
      
          var origCreateDataChannel =
            window.RTCPeerConnection.prototype.createDataChannel;
          window.RTCPeerConnection.prototype.createDataChannel = function() {
            var pc = this;
            var dataChannel = origCreateDataChannel.apply(pc, arguments);
            var origDataChannelSend = dataChannel.send;
      
            // Patch 'send' method
            dataChannel.send = function() {
              var dc = this;
              var data = arguments[0];
              var length = data.length || data.size || data.byteLength;
              if (length > pc.sctp.maxMessageSize) {
                throw new DOMException('Message too large (can send a maximum of ' +
                  pc.sctp.maxMessageSize + ' bytes)', 'TypeError');
              }
              return origDataChannelSend.apply(dc, arguments);
            };
      
            return dataChannel;
          };
        }
      };
      
      },{"./utils":13,"sdp":2}],8:[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 utils = require('../utils');
      var shimRTCPeerConnection = require('rtcpeerconnection-shim');
      
      module.exports = {
        shimGetUserMedia: require('./getusermedia'),
        shimPeerConnection: function(window) {
          var browserDetails = utils.detectBrowser(window);
      
          if (window.RTCIceGatherer) {
            // ORTC defines an RTCIceCandidate object but no constructor.
            // Not implemented in Edge.
            if (!window.RTCIceCandidate) {
              window.RTCIceCandidate = function(args) {
                return args;
              };
            }
            // ORTC does not have a session description object but
            // other browsers (i.e. Chrome) that will support both PC and ORTC
            // in the future might have this defined already.
            if (!window.RTCSessionDescription) {
              window.RTCSessionDescription = function(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(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() {
                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;
              }
            });
          }
      
          window.RTCPeerConnection =
              shimRTCPeerConnection(window, browserDetails.version);
        },
        shimReplaceTrack: function(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":13,"./getusermedia":9,"rtcpeerconnection-shim":1}],9:[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';
      
      // Expose public methods.
      module.exports = function(window) {
        var navigator = window && window.navigator;
      
        var shimError_ = function(e) {
          return {
            name: {PermissionDeniedError: 'NotAllowedError'}[e.name] || e.name,
            message: e.message,
            constraint: e.constraint,
            toString: function() {
              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));
          });
        };
      };
      
      },{}],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';
      
      var utils = require('../utils');
      
      module.exports = {
        shimGetUserMedia: require('./getusermedia'),
        shimOnTrack: function(window) {
          if (typeof window === 'object' && window.RTCPeerConnection && !('ontrack' in
              window.RTCPeerConnection.prototype)) {
            Object.defineProperty(window.RTCPeerConnection.prototype, 'ontrack', {
              get: function() {
                return this._ontrack;
              },
              set: function(f) {
                if (this._ontrack) {
                  this.removeEventListener('track', this._ontrack);
                  this.removeEventListener('addstream', this._ontrackpoly);
                }
                this.addEventListener('track', this._ontrack = f);
                this.addEventListener('addstream', this._ontrackpoly = function(e) {
                  e.stream.getTracks().forEach(function(track) {
                    var event = new Event('track');
                    event.track = track;
                    event.receiver = {track: track};
                    event.transceiver = {receiver: event.receiver};
                    event.streams = [e.stream];
                    this.dispatchEvent(event);
                  }.bind(this));
                }.bind(this));
              }
            });
          }
          if (typeof window === 'object' && window.RTCTrackEvent &&
              ('receiver' in window.RTCTrackEvent.prototype) &&
              !('transceiver' in window.RTCTrackEvent.prototype)) {
            Object.defineProperty(window.RTCTrackEvent.prototype, 'transceiver', {
              get: function() {
                return {receiver: this.receiver};
              }
            });
          }
        },
      
        shimSourceObject: function(window) {
          // Firefox has supported mozSrcObject since FF22, unprefixed in 42.
          if (typeof window === 'object') {
            if (window.HTMLMediaElement &&
              !('srcObject' in window.HTMLMediaElement.prototype)) {
              // Shim the srcObject property, once, when HTMLMediaElement is found.
              Object.defineProperty(window.HTMLMediaElement.prototype, 'srcObject', {
                get: function() {
                  return this.mozSrcObject;
                },
                set: function(stream) {
                  this.mozSrcObject = stream;
                }
              });
            }
          }
        },
      
        shimPeerConnection: function(window) {
          var browserDetails = utils.detectBrowser(window);
      
          if (typeof window !== 'object' || !(window.RTCPeerConnection ||
              window.mozRTCPeerConnection)) {
            return; // probably media.peerconnection.enabled=false in about:config
          }
          // The RTCPeerConnection object.
          if (!window.RTCPeerConnection) {
            window.RTCPeerConnection = function(pcConfig, pcConstraints) {
              if (browserDetails.version < 38) {
                // .urls is not supported in FF < 38.
                // create RTCIceServers with a single url.
                if (pcConfig && pcConfig.iceServers) {
                  var newIceServers = [];
                  for (var i = 0; i < pcConfig.iceServers.length; i++) {
                    var server = pcConfig.iceServers[i];
                    if (server.hasOwnProperty('urls')) {
                      for (var j = 0; j < server.urls.length; j++) {
                        var newServer = {
                          url: server.urls[j]
                        };
                        if (server.urls[j].indexOf('turn') === 0) {
                          newServer.username = server.username;
                          newServer.credential = server.credential;
                        }
                        newIceServers.push(newServer);
                      }
                    } else {
                      newIceServers.push(pcConfig.iceServers[i]);
                    }
                  }
                  pcConfig.iceServers = newIceServers;
                }
              }
              return new window.mozRTCPeerConnection(pcConfig, pcConstraints);
            };
            window.RTCPeerConnection.prototype =
                window.mozRTCPeerConnection.prototype;
      
            // wrap static methods. Currently just generateCertificate.
            if (window.mozRTCPeerConnection.generateCertificate) {
              Object.defineProperty(window.RTCPeerConnection, 'generateCertificate', {
                get: function() {
                  return window.mozRTCPeerConnection.generateCertificate;
                }
              });
            }
      
            window.RTCSessionDescription = window.mozRTCSessionDescription;
            window.RTCIceCandidate = window.mozRTCIceCandidate;
          }
      
          // shim away need for obsolete RTCIceCandidate/RTCSessionDescription.
          ['setLocalDescription', 'setRemoteDescription', 'addIceCandidate']
              .forEach(function(method) {
                var nativeMethod = window.RTCPeerConnection.prototype[method];
                window.RTCPeerConnection.prototype[method] = function() {
                  arguments[0] = new ((method === 'addIceCandidate') ?
                      window.RTCIceCandidate :
                      window.RTCSessionDescription)(arguments[0]);
                  return nativeMethod.apply(this, arguments);
                };
              });
      
          // support for addIceCandidate(null or undefined)
          var nativeAddIceCandidate =
              window.RTCPeerConnection.prototype.addIceCandidate;
          window.RTCPeerConnection.prototype.addIceCandidate = function() {
            if (!arguments[0]) {
              if (arguments[1]) {
                arguments[1].apply(null);
              }
              return Promise.resolve();
            }
            return nativeAddIceCandidate.apply(this, arguments);
          };
      
          // shim getStats with maplike support
          var makeMapStats = function(stats) {
            var map = new Map();
            Object.keys(stats).forEach(function(key) {
              map.set(key, stats[key]);
              map[key] = stats[key];
            });
            return map;
          };
      
          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(
            selector,
            onSucc,
            onErr
          ) {
            return nativeGetStats.apply(this, [selector || null])
              .then(function(stats) {
                if (browserDetails.version < 48) {
                  stats = makeMapStats(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);
          };
        },
      
        shimRemoveStream: function(window) {
          if (!window.RTCPeerConnection ||
              'removeStream' in window.RTCPeerConnection.prototype) {
            return;
          }
          window.RTCPeerConnection.prototype.removeStream = function(stream) {
            var pc = this;
            utils.deprecated('removeStream', 'removeTrack');
            this.getSenders().forEach(function(sender) {
              if (sender.track && stream.getTracks().indexOf(sender.track) !== -1) {
                pc.removeTrack(sender);
              }
            });
          };
        }
      };
      
      },{"../utils":13,"./getusermedia":11}],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';
      
      var utils = require('../utils');
      var logging = utils.log;
      
      // Expose public methods.
      module.exports = function(window) {
        var browserDetails = utils.detectBrowser(window);
        var navigator = window && window.navigator;
        var MediaStreamTrack = window && window.MediaStreamTrack;
      
        var shimError_ = function(e) {
          return {
            name: {
              InternalError: 'NotReadableError',
              NotSupportedError: 'TypeError',
              PermissionDeniedError: 'NotAllowedError',
              SecurityError: 'NotAllowedError'
            }[e.name] || e.name,
            message: {
              'The operation is insecure.': 'The request is not allowed by the ' +
              'user agent or the platform in the current context.'
            }[e.message] || e.message,
            constraint: e.constraint,
            toString: function() {
              return this.name + (this.message && ': ') + this.message;
            }
          };
        };
      
        // getUserMedia constraints shim.
        var getUserMedia_ = function(constraints, onSuccess, onError) {
          var constraintsToFF37_ = function(c) {
            if (typeof c !== 'object' || c.require) {
              return c;
            }
            var require = [];
            Object.keys(c).forEach(function(key) {
              if (key === 'require' || key === 'advanced' || key === 'mediaSource') {
                return;
              }
              var r = c[key] = (typeof c[key] === 'object') ?
                  c[key] : {ideal: c[key]};
              if (r.min !== undefined ||
                  r.max !== undefined || r.exact !== undefined) {
                require.push(key);
              }
              if (r.exact !== undefined) {
                if (typeof r.exact === 'number') {
                  r. min = r.max = r.exact;
                } else {
                  c[key] = r.exact;
                }
                delete r.exact;
              }
              if (r.ideal !== undefined) {
                c.advanced = c.advanced || [];
                var oc = {};
                if (typeof r.ideal === 'number') {
                  oc[key] = {min: r.ideal, max: r.ideal};
                } else {
                  oc[key] = r.ideal;
                }
                c.advanced.push(oc);
                delete r.ideal;
                if (!Object.keys(r).length) {
                  delete c[key];
                }
              }
            });
            if (require.length) {
              c.require = require;
            }
            return c;
          };
          constraints = JSON.parse(JSON.stringify(constraints));
          if (browserDetails.version < 38) {
            logging('spec: ' + JSON.stringify(constraints));
            if (constraints.audio) {
              constraints.audio = constraintsToFF37_(constraints.audio);
            }
            if (constraints.video) {
              constraints.video = constraintsToFF37_(constraints.video);
            }
            logging('ff37: ' + JSON.stringify(constraints));
          }
          return navigator.mozGetUserMedia(constraints, onSuccess, function(e) {
            onError(shimError_(e));
          });
        };
      
        // Returns the result of getUserMedia as a Promise.
        var getUserMediaPromise_ = function(constraints) {
          return new Promise(function(resolve, reject) {
            getUserMedia_(constraints, resolve, reject);
          });
        };
      
        // Shim for mediaDevices on older versions.
        if (!navigator.mediaDevices) {
          navigator.mediaDevices = {getUserMedia: getUserMediaPromise_,
            addEventListener: function() { },
            removeEventListener: function() { }
          };
        }
        navigator.mediaDevices.enumerateDevices =
            navigator.mediaDevices.enumerateDevices || function() {
              return new Promise(function(resolve) {
                var infos = [
                  {kind: 'audioinput', deviceId: 'default', label: '', groupId: ''},
                  {kind: 'videoinput', deviceId: 'default', label: '', groupId: ''}
                ];
                resolve(infos);
              });
            };
      
        if (browserDetails.version < 41) {
          // Work around http://bugzil.la/1169665
          var orgEnumerateDevices =
              navigator.mediaDevices.enumerateDevices.bind(navigator.mediaDevices);
          navigator.mediaDevices.enumerateDevices = function() {
            return orgEnumerateDevices().then(undefined, function(e) {
              if (e.name === 'NotFoundError') {
                return [];
              }
              throw e;
            });
          };
        }
        if (browserDetails.version < 49) {
          var origGetUserMedia = navigator.mediaDevices.getUserMedia.
              bind(navigator.mediaDevices);
          navigator.mediaDevices.getUserMedia = function(c) {
            return origGetUserMedia(c).then(function(stream) {
              // Work around https://bugzil.la/802326
              if (c.audio && !stream.getAudioTracks().length ||
                  c.video && !stream.getVideoTracks().length) {
                stream.getTracks().forEach(function(track) {
                  track.stop();
                });
                throw new DOMException('The object can not be found here.',
                                       'NotFoundError');
              }
              return stream;
            }, function(e) {
              return Promise.reject(shimError_(e));
            });
          };
        }
        if (!(browserDetails.version > 55 &&
            'autoGainControl' in navigator.mediaDevices.getSupportedConstraints())) {
          var remap = function(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 === '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 === 'object') {
                c = JSON.parse(JSON.stringify(c));
                remap(c, 'autoGainControl', 'mozAutoGainControl');
                remap(c, 'noiseSuppression', 'mozNoiseSuppression');
              }
              return nativeApplyConstraints.apply(this, [c]);
            };
          }
        }
        navigator.getUserMedia = function(constraints, onSuccess, onError) {
          if (browserDetails.version < 44) {
            return getUserMedia_(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);
        };
      };
      
      },{"../utils":13}],12:[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';
      var utils = require('../utils');
      
      module.exports = {
        shimLocalStreamsAPI: function(window) {
          if (typeof window !== 'object' || !window.RTCPeerConnection) {
            return;
          }
          if (!('getLocalStreams' in window.RTCPeerConnection.prototype)) {
            window.RTCPeerConnection.prototype.getLocalStreams = function() {
              if (!this._localStreams) {
                this._localStreams = [];
              }
              return this._localStreams;
            };
          }
          if (!('getStreamById' in window.RTCPeerConnection.prototype)) {
            window.RTCPeerConnection.prototype.getStreamById = function(id) {
              var result = null;
              if (this._localStreams) {
                this._localStreams.forEach(function(stream) {
                  if (stream.id === id) {
                    result = stream;
                  }
                });
              }
              if (this._remoteStreams) {
                this._remoteStreams.forEach(function(stream) {
                  if (stream.id === id) {
                    result = stream;
                  }
                });
              }
              return result;
            };
          }
          if (!('addStream' in window.RTCPeerConnection.prototype)) {
            var _addTrack = window.RTCPeerConnection.prototype.addTrack;
            window.RTCPeerConnection.prototype.addStream = function(stream) {
              if (!this._localStreams) {
                this._localStreams = [];
              }
              if (this._localStreams.indexOf(stream) === -1) {
                this._localStreams.push(stream);
              }
              var pc = this;
              stream.getTracks().forEach(function(track) {
                _addTrack.call(pc, track, stream);
              });
            };
      
            window.RTCPeerConnection.prototype.addTrack = function(track, stream) {
              if (stream) {
                if (!this._localStreams) {
                  this._localStreams = [stream];
                } else if (this._localStreams.indexOf(stream) === -1) {
                  this._localStreams.push(stream);
                }
              }
              return _addTrack.call(this, track, stream);
            };
          }
          if (!('removeStream' in window.RTCPeerConnection.prototype)) {
            window.RTCPeerConnection.prototype.removeStream = function(stream) {
              if (!this._localStreams) {
                this._localStreams = [];
              }
              var index = this._localStreams.indexOf(stream);
              if (index === -1) {
                return;
              }
              this._localStreams.splice(index, 1);
              var pc = this;
              var tracks = stream.getTracks();
              this.getSenders().forEach(function(sender) {
                if (tracks.indexOf(sender.track) !== -1) {
                  pc.removeTrack(sender);
                }
              });
            };
          }
        },
        shimRemoteStreamsAPI: function(window) {
          if (typeof window !== 'object' || !window.RTCPeerConnection) {
            return;
          }
          if (!('getRemoteStreams' in window.RTCPeerConnection.prototype)) {
            window.RTCPeerConnection.prototype.getRemoteStreams = function() {
              return this._remoteStreams ? this._remoteStreams : [];
            };
          }
          if (!('onaddstream' in window.RTCPeerConnection.prototype)) {
            Object.defineProperty(window.RTCPeerConnection.prototype, 'onaddstream', {
              get: function() {
                return this._onaddstream;
              },
              set: function(f) {
                var pc = 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 (!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);
                  });
                });
              }
            });
          }
        },
        shimCallbacksAPI: function(window) {
          if (typeof window !== 'object' || !window.RTCPeerConnection) {
            return;
          }
          var prototype = window.RTCPeerConnection.prototype;
          var createOffer = prototype.createOffer;
          var createAnswer = prototype.createAnswer;
          var setLocalDescription = prototype.setLocalDescription;
          var setRemoteDescription = prototype.setRemoteDescription;
          var addIceCandidate = prototype.addIceCandidate;
      
          prototype.createOffer = function(successCallback, failureCallback) {
            var options = (arguments.length >= 2) ? arguments[2] : arguments[0];
            var promise = createOffer.apply(this, [options]);
            if (!failureCallback) {
              return promise;
            }
            promise.then(successCallback, failureCallback);
            return Promise.resolve();
          };
      
          prototype.createAnswer = function(successCallback, failureCallback) {
            var options = (arguments.length >= 2) ? arguments[2] : arguments[0];
            var promise = createAnswer.apply(this, [options]);
            if (!failureCallback) {
              return promise;
            }
            promise.then(successCallback, failureCallback);
            return Promise.resolve();
          };
      
          var withCallback = function(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(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(candidate, successCallback, failureCallback) {
            var promise = addIceCandidate.apply(this, [candidate]);
            if (!failureCallback) {
              return promise;
            }
            promise.then(successCallback, failureCallback);
            return Promise.resolve();
          };
          prototype.addIceCandidate = withCallback;
        },
        shimGetUserMedia: function(window) {
          var navigator = window && window.navigator;
      
          if (!navigator.getUserMedia) {
            if (navigator.webkitGetUserMedia) {
              navigator.getUserMedia = navigator.webkitGetUserMedia.bind(navigator);
            } else if (navigator.mediaDevices &&
                navigator.mediaDevices.getUserMedia) {
              navigator.getUserMedia = function(constraints, cb, errcb) {
                navigator.mediaDevices.getUserMedia(constraints)
                .then(cb, errcb);
              }.bind(navigator);
            }
          }
        },
        shimRTCIceServerUrls: function(window) {
          // migrate from non-spec RTCIceServer.url to RTCIceServer.urls
          var OrigPeerConnection = window.RTCPeerConnection;
          window.RTCPeerConnection = function(pcConfig, pcConstraints) {
            if (pcConfig && pcConfig.iceServers) {
              var newIceServers = [];
              for (var i = 0; i < pcConfig.iceServers.length; i++) {
                var server = pcConfig.iceServers[i];
                if (!server.hasOwnProperty('urls') &&
                    server.hasOwnProperty('url')) {
                  utils.deprecated('RTCIceServer.url', 'RTCIceServer.urls');
                  server = JSON.parse(JSON.stringify(server));
                  server.urls = server.url;
                  delete server.url;
                  newIceServers.push(server);
                } else {
                  newIceServers.push(pcConfig.iceServers[i]);
                }
              }
              pcConfig.iceServers = newIceServers;
            }
            return new OrigPeerConnection(pcConfig, pcConstraints);
          };
          window.RTCPeerConnection.prototype = OrigPeerConnection.prototype;
          // wrap static methods. Currently just generateCertificate.
          if ('generateCertificate' in window.RTCPeerConnection) {
            Object.defineProperty(window.RTCPeerConnection, 'generateCertificate', {
              get: function() {
                return OrigPeerConnection.generateCertificate;
              }
            });
          }
        },
        shimTrackEventTransceiver: function(window) {
          // Add event.transceiver member over deprecated event.receiver
          if (typeof window === 'object' && window.RTCPeerConnection &&
              ('receiver' in window.RTCTrackEvent.prototype) &&
              // can't check 'transceiver' in window.RTCTrackEvent.prototype, as it is
              // defined for some reason even when window.RTCTransceiver is not.
              !window.RTCTransceiver) {
            Object.defineProperty(window.RTCTrackEvent.prototype, 'transceiver', {
              get: function() {
                return {receiver: this.receiver};
              }
            });
          }
        },
      
        shimCreateOfferLegacy: function(window) {
          var origCreateOffer = window.RTCPeerConnection.prototype.createOffer;
          window.RTCPeerConnection.prototype.createOffer = function(offerOptions) {
            var pc = this;
            if (offerOptions) {
              var audioTransceiver = pc.getTransceivers().find(function(transceiver) {
                return transceiver.sender.track &&
                    transceiver.sender.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) {
                pc.addTransceiver('audio');
              }
      
              var videoTransceiver = pc.getTransceivers().find(function(transceiver) {
                return transceiver.sender.track &&
                    transceiver.sender.track.kind === 'video';
              });
              if (offerOptions.offerToReceiveVideo === false && videoTransceiver) {
                if (videoTransceiver.direction === 'sendrecv') {
                  videoTransceiver.setDirection('sendonly');
                } else if (videoTransceiver.direction === 'recvonly') {
                  videoTransceiver.setDirection('inactive');
                }
              } else if (offerOptions.offerToReceiveVideo === true &&
                  !videoTransceiver) {
                pc.addTransceiver('video');
              }
            }
            return origCreateOffer.apply(pc, arguments);
          };
        }
      };
      
      },{"../utils":13}],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';
      
      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.
      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(e) {
            cb(wrapper(e));
          };
          this._eventMap = this._eventMap || {};
          this._eventMap[cb] = wrappedCallback;
          return nativeAddEventListener.apply(this, [nativeEventName,
            wrappedCallback]);
        };
      
        var nativeRemoveEventListener = proto.removeEventListener;
        proto.removeEventListener = function(nativeEventName, cb) {
          if (nativeEventName !== eventNameToWrap || !this._eventMap
              || !this._eventMap[cb]) {
            return nativeRemoveEventListener.apply(this, arguments);
          }
          var unwrappedCb = this._eventMap[cb];
          delete this._eventMap[cb];
          return nativeRemoveEventListener.apply(this, [nativeEventName,
            unwrappedCb]);
        };
      
        Object.defineProperty(proto, 'on' + eventNameToWrap, {
          get: function() {
            return this['_on' + eventNameToWrap];
          },
          set: function(cb) {
            if (this['_on' + eventNameToWrap]) {
              this.removeEventListener(eventNameToWrap,
                  this['_on' + eventNameToWrap]);
              delete this['_on' + eventNameToWrap];
            }
            if (cb) {
              this.addEventListener(eventNameToWrap,
                  this['_on' + eventNameToWrap] = cb);
            }
          }
        });
      }
      
      // Utility methods.
      module.exports = {
        extractVersion: extractVersion,
        wrapPeerConnectionEvent: wrapPeerConnectionEvent,
        disableLog: function(bool) {
          if (typeof bool !== 'boolean') {
            return new Error('Argument type: ' + 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.
         */
        disableWarnings: function(bool) {
          if (typeof bool !== 'boolean') {
            return new Error('Argument type: ' + typeof bool +
                '. Please use a boolean.');
          }
          deprecationWarnings_ = !bool;
          return 'adapter.js deprecation warnings ' + (bool ? 'disabled' : 'enabled');
        },
      
        log: function() {
          if (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.
         */
        deprecated: function(oldMethod, newMethod) {
          if (!deprecationWarnings_) {
            return;
          }
          console.warn(oldMethod + ' is deprecated, please use ' + newMethod +
              ' instead.');
        },
      
        /**
         * Browser detector.
         *
         * @return {object} result containing browser and version
         *     properties.
         */
        detectBrowser: function(window) {
          var navigator = window && window.navigator;
      
          // Returned result object.
          var result = {};
          result.browser = null;
          result.version = null;
      
          // Fail early if it's not a browser
          if (typeof window === 'undefined' || !window.navigator) {
            result.browser = 'Not a browser.';
            return result;
          }
      
          if (navigator.mozGetUserMedia) { // Firefox.
            result.browser = 'firefox';
            result.version = extractVersion(navigator.userAgent,
                /Firefox\/(\d+)\./, 1);
          } else if (navigator.webkitGetUserMedia) {
            // Chrome, Chromium, Webview, Opera.
            // Version matches Chrome/WebRTC version.
            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 (navigator.mediaDevices &&
              navigator.userAgent.match(/AppleWebKit\/(\d+)\./)) { // Safari.
            result.browser = 'safari';
            result.version = extractVersion(navigator.userAgent,
                /AppleWebKit\/(\d+)\./, 1);
          } else { // Default fallthrough: not supported.
            result.browser = 'Not a supported browser.';
            return result;
          }
      
          return result;
        }
      };
      
      },{}]},{},[3])(3)
      });