path: root/js/lib/adapter.js

(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.adapter = f()}})(function(){var define,module,exports;return (function 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){
 /* 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: parts[1],
    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;
      default: // Unknown extensions are silently ignored.
        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);
  }
  return 'candidate:' + sdp.join(' ');
};

// 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
SDPUtils.parseExtmap = function(line) {
  var parts = line.substr(9).split(' ');
  return {
    id: parseInt(parts[0], 10),
    uri: parts[1]
  };
};

// Generates a=extmap line from RTCRtpHeaderExtensionParameters or
// RTCRtpHeaderExtension.
SDPUtils.writeExtmap = function(headerExtension) {
  return 'a=extmap:' + (headerExtension.id || headerExtension.preferredId) +
       ' ' + 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 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.splitLines(mediaSection);
  // Search in session part, too.
  lines = lines.concat(SDPUtils.splitLines(sessionpart));
  var fpLine = lines.filter(function(line) {
    return line.indexOf('a=fingerprint:') === 0;
  })[0].substr(14);
  // Note: a=setup line is ignored since we use the 'auto' role.
  var dtlsParameters = {
    role: 'auto',
    fingerprints: [{
      algorithm: fpLine.split(' ')[0],
      value: fpLine.split(' ')[1]
    }]
  };
  return dtlsParameters;
};

// 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) {
      bandwidth = parseInt(bandwidth[0].substr(5), 10);
    }
    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 an 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]};
  }
};

SDPUtils.writeSessionBoilerplate = function() {
  // FIXME: sess-id should be an NTP timestamp.
  return 'v=0\r\n' +
      'o=thisisadapterortc 8169639915646943137 2 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.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';
};

// Expose public methods.
module.exports = SDPUtils;

},{}],2:[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';

// Shimming starts here.
(function() {
  // Utils.
  var utils = require('./utils');
  var logging = utils.log;
  var browserDetails = utils.browserDetails;
  // Export to the adapter global object visible in the browser.
  module.exports.browserDetails = browserDetails;
  module.exports.extractVersion = utils.extractVersion;
  module.exports.disableLog = utils.disableLog;

  // 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;

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

      chromeShim.shimGetUserMedia();
      chromeShim.shimMediaStream();
      utils.shimCreateObjectURL();
      chromeShim.shimSourceObject();
      chromeShim.shimPeerConnection();
      chromeShim.shimOnTrack();
      chromeShim.shimGetSendersWithDtmf();
      break;
    case 'firefox':
      if (!firefoxShim || !firefoxShim.shimPeerConnection) {
        logging('Firefox shim is not included in this adapter release.');
        return;
      }
      logging('adapter.js shimming firefox.');
      // Export to the adapter global object visible in the browser.
      module.exports.browserShim = firefoxShim;

      firefoxShim.shimGetUserMedia();
      utils.shimCreateObjectURL();
      firefoxShim.shimSourceObject();
      firefoxShim.shimPeerConnection();
      firefoxShim.shimOnTrack();
      break;
    case 'edge':
      if (!edgeShim || !edgeShim.shimPeerConnection) {
        logging('MS edge shim is not included in this adapter release.');
        return;
      }
      logging('adapter.js shimming edge.');
      // Export to the adapter global object visible in the browser.
      module.exports.browserShim = edgeShim;

      edgeShim.shimGetUserMedia();
      utils.shimCreateObjectURL();
      edgeShim.shimPeerConnection();
      break;
    case 'safari':
      if (!safariShim) {
        logging('Safari shim is not included in this adapter release.');
        return;
      }
      logging('adapter.js shimming safari.');
      // Export to the adapter global object visible in the browser.
      module.exports.browserShim = safariShim;

      safariShim.shimGetUserMedia();
      break;
    default:
      logging('Unsupported browser!');
  }
})();

},{"./chrome/chrome_shim":3,"./edge/edge_shim":5,"./firefox/firefox_shim":7,"./safari/safari_shim":9,"./utils":10}],3:[function(require,module,exports){

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

var chromeShim = {
  shimMediaStream: function() {
    window.MediaStream = window.MediaStream || window.webkitMediaStream;
  },

  shimOnTrack: function() {
    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) {
          var self = this;
          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) {
            // 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 event = new Event('track');
              event.track = te.track;
              event.receiver = {track: te.track};
              event.streams = [e.stream];
              self.dispatchEvent(event);
            });
            e.stream.getTracks().forEach(function(track) {
              var event = new Event('track');
              event.track = track;
              event.receiver = {track: track};
              event.streams = [e.stream];
              this.dispatchEvent(event);
            }.bind(this));
          }.bind(this));
        }
      });
    }
  },

  shimGetSendersWithDtmf: function() {
    if (typeof window === 'object' && window.RTCPeerConnection &&
        !('getSenders' in RTCPeerConnection.prototype) &&
        'createDTMFSender' in RTCPeerConnection.prototype) {
      RTCPeerConnection.prototype.getSenders = function() {
        return this._senders;
      };
      var origAddStream = RTCPeerConnection.prototype.addStream;
      var origRemoveStream = RTCPeerConnection.prototype.removeStream;

      RTCPeerConnection.prototype.addStream = function(stream) {
        var pc = this;
        pc._senders = pc._senders || [];
        origAddStream.apply(pc, [stream]);
        stream.getTracks().forEach(function(track) {
          pc._senders.push({
            track: track,
            get dtmf() {
              if (this._dtmf === undefined) {
                if (track.kind === 'audio') {
                  this._dtmf = pc.createDTMFSender(track);
                } else {
                  this._dtmf = null;
                }
              }
              return this._dtmf;
            }
          });
        });
      };

      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
          }
        });
      };
    }
  },

  shimSourceObject: function() {
    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);
            });
          }
        });
      }
    }
  },

  shimPeerConnection: function() {
    // The RTCPeerConnection object.
    if (!window.RTCPeerConnection) {
      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 webkitRTCPeerConnection(pcConfig, pcConstraints);
      };
      window.RTCPeerConnection.prototype = webkitRTCPeerConnection.prototype;
      // wrap static methods. Currently just generateCertificate.
      if (webkitRTCPeerConnection.generateCertificate) {
        Object.defineProperty(window.RTCPeerConnection, 'generateCertificate', {
          get: function() {
            return webkitRTCPeerConnection.generateCertificate;
          }
        });
      }
    }

    var origGetStats = RTCPeerConnection.prototype.getStats;
    RTCPeerConnection.prototype.getStats = function(selector,
        successCallback, errorCallback) {
      var self = 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(self, [
          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 = RTCPeerConnection.prototype[method];
            RTCPeerConnection.prototype[method] = function() {
              var args = arguments;
              var self = this;
              var promise = new Promise(function(resolve, reject) {
                nativeMethod.apply(self, [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 = RTCPeerConnection.prototype[method];
        RTCPeerConnection.prototype[method] = function() {
          var self = 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(self, [resolve, reject, opts]);
            });
          }
          return nativeMethod.apply(this, arguments);
        };
      });
    }

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

    // support for addIceCandidate(null or undefined)
    var nativeAddIceCandidate =
        RTCPeerConnection.prototype.addIceCandidate;
    RTCPeerConnection.prototype.addIceCandidate = function() {
      if (!arguments[0]) {
        if (arguments[1]) {
          arguments[1].apply(null);
        }
        return Promise.resolve();
      }
      return nativeAddIceCandidate.apply(this, arguments);
    };
  }
};


// Expose public methods.
module.exports = {
  shimMediaStream: chromeShim.shimMediaStream,
  shimOnTrack: chromeShim.shimOnTrack,
  shimGetSendersWithDtmf: chromeShim.shimGetSendersWithDtmf,
  shimSourceObject: chromeShim.shimSourceObject,
  shimPeerConnection: chromeShim.shimPeerConnection,
  shimGetUserMedia: require('./getusermedia')
};

},{"../utils.js":10,"./getusermedia":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 logging = require('../utils.js').log;
var browserDetails = require('../utils.js').browserDetails;

// Expose public methods.
module.exports = function() {
  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) {
    constraints = JSON.parse(JSON.stringify(constraints));
    if (constraints && constraints.audio) {
      constraints.audio = constraintsToChrome_(constraints.audio);
    }
    if (constraints && typeof constraints.video === 'object') {
      // Shim facingMode for mobile, where it defaults to "user".
      var face = constraints.video.facingMode;
      face = face && ((typeof face === 'object') ? face : {ideal: face});
      var getSupportedFacingModeLies = browserDetails.version < 59;

      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;
        if (face.exact === 'environment' || face.ideal === 'environment') {
          // Look for "back" in label, or use last cam (typically back cam).
          return navigator.mediaDevices.enumerateDevices()
          .then(function(devices) {
            devices = devices.filter(function(d) {
              return d.kind === 'videoinput';
            });
            var back = devices.find(function(d) {
              return d.label.toLowerCase().indexOf('back') !== -1;
            }) || (devices.length && devices[devices.length - 1]);
            if (back) {
              constraints.video.deviceId = face.exact ? {exact: back.deviceId} :
                                                        {ideal: back.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',
        ConstraintNotSatisfiedError: 'OverconstrainedError'
      }[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) {
        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 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":10}],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 SDPUtils = require('sdp');
var browserDetails = require('../utils').browserDetails;

// sort tracks such that they follow an a-v-a-v...
// pattern.
function sortTracks(tracks) {
  var audioTracks = tracks.filter(function(track) {
    return track.kind === 'audio';
  });
  var videoTracks = tracks.filter(function(track) {
    return track.kind === 'video';
  });
  tracks = [];
  while (audioTracks.length || videoTracks.length) {
    if (audioTracks.length) {
      tracks.push(audioTracks.shift());
    }
    if (videoTracks.length) {
      tracks.push(videoTracks.shift());
    }
  }
  return tracks;
}

// Edge does not like
// 1) stun:
// 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) {
  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;
      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 &&
            browserDetails.version >= 14393;
      });

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

var edgeShim = {
  shimPeerConnection: function() {
    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(
            MediaStreamTrack.prototype, 'enabled');
        Object.defineProperty(MediaStreamTrack.prototype, 'enabled', {
          set: function(value) {
            origMSTEnabled.set.call(this, value);
            var ev = new Event('enabled');
            ev.enabled = value;
            this.dispatchEvent(ev);
          }
        });
      }
    }

    window.RTCPeerConnection = function(config) {
      var self = this;

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

      this.onicecandidate = null;
      this.onaddstream = null;
      this.ontrack = null;
      this.onremovestream = null;
      this.onsignalingstatechange = null;
      this.oniceconnectionstatechange = null;
      this.onicegatheringstatechange = null;
      this.onnegotiationneeded = null;
      this.ondatachannel = null;

      this.localStreams = [];
      this.remoteStreams = [];
      this.getLocalStreams = function() {
        return self.localStreams;
      };
      this.getRemoteStreams = function() {
        return self.remoteStreams;
      };

      this.localDescription = new RTCSessionDescription({
        type: '',
        sdp: ''
      });
      this.remoteDescription = new RTCSessionDescription({
        type: '',
        sdp: ''
      });
      this.signalingState = 'stable';
      this.iceConnectionState = 'new';
      this.iceGatheringState = 'new';

      this.iceOptions = {
        gatherPolicy: 'all',
        iceServers: []
      };
      if (config && config.iceTransportPolicy) {
        switch (config.iceTransportPolicy) {
          case 'all':
          case 'relay':
            this.iceOptions.gatherPolicy = config.iceTransportPolicy;
            break;
          default:
            // don't set iceTransportPolicy.
            break;
        }
      }
      this.usingBundle = config && config.bundlePolicy === 'max-bundle';

      if (config && config.iceServers) {
        this.iceOptions.iceServers = filterIceServers(config.iceServers);
      }
      this._config = config;

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

      // since the iceGatherer is currently created in createOffer but we
      // must not emit candidates until after setLocalDescription we buffer
      // them in this array.
      this._localIceCandidatesBuffer = [];
    };

    window.RTCPeerConnection.prototype._emitGatheringStateChange = function() {
      var event = new Event('icegatheringstatechange');
      this.dispatchEvent(event);
      if (this.onicegatheringstatechange !== null) {
        this.onicegatheringstatechange(event);
      }
    };

    window.RTCPeerConnection.prototype._emitBufferedCandidates = function() {
      var self = this;
      var sections = SDPUtils.splitSections(self.localDescription.sdp);
      // FIXME: need to apply ice candidates in a way which is async but
      // in-order
      this._localIceCandidatesBuffer.forEach(function(event) {
        var end = !event.candidate || Object.keys(event.candidate).length === 0;
        if (end) {
          for (var j = 1; j < sections.length; j++) {
            if (sections[j].indexOf('\r\na=end-of-candidates\r\n') === -1) {
              sections[j] += 'a=end-of-candidates\r\n';
            }
          }
        } else {
          sections[event.candidate.sdpMLineIndex + 1] +=
              'a=' + event.candidate.candidate + '\r\n';
        }
        self.localDescription.sdp = sections.join('');
        self.dispatchEvent(event);
        if (self.onicecandidate !== null) {
          self.onicecandidate(event);
        }
        if (!event.candidate && self.iceGatheringState !== 'complete') {
          var complete = self.transceivers.every(function(transceiver) {
            return transceiver.iceGatherer &&
                transceiver.iceGatherer.state === 'completed';
          });
          if (complete && self.iceGatheringStateChange !== 'complete') {
            self.iceGatheringState = 'complete';
            self._emitGatheringStateChange();
          }
        }
      });
      this._localIceCandidatesBuffer = [];
    };

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

    window.RTCPeerConnection.prototype.addStream = function(stream) {
      if (browserDetails.version >= 15025) {
        this.localStreams.push(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;
          });
        });
        this.localStreams.push(clonedStream);
      }
      this._maybeFireNegotiationNeeded();
    };

    window.RTCPeerConnection.prototype.removeStream = function(stream) {
      var idx = this.localStreams.indexOf(stream);
      if (idx > -1) {
        this.localStreams.splice(idx, 1);
        this._maybeFireNegotiationNeeded();
      }
    };

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

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

    // Determines the intersection of local and remote capabilities.
    window.RTCPeerConnection.prototype._getCommonCapabilities =
        function(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;
        };

    // Create ICE gatherer, ICE transport and DTLS transport.
    window.RTCPeerConnection.prototype._createIceAndDtlsTransports =
        function(mid, sdpMLineIndex) {
          var self = this;
          var iceGatherer = new RTCIceGatherer(self.iceOptions);
          var iceTransport = new RTCIceTransport(iceGatherer);
          iceGatherer.onlocalcandidate = function(evt) {
            var event = new Event('icecandidate');
            event.candidate = {sdpMid: mid, sdpMLineIndex: sdpMLineIndex};

            var cand = evt.candidate;
            var end = !cand || Object.keys(cand).length === 0;
            // Edge emits an empty object for RTCIceCandidateComplete‥
            if (end) {
              // polyfill since RTCIceGatherer.state is not implemented in
              // Edge 10547 yet.
              if (iceGatherer.state === undefined) {
                iceGatherer.state = 'completed';
              }
            } else {
              // RTCIceCandidate doesn't have a component, needs to be added
              cand.component = iceTransport.component === 'RTCP' ? 2 : 1;
              event.candidate.candidate = SDPUtils.writeCandidate(cand);
            }

            // update local description.
            var sections = SDPUtils.splitSections(self.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';
            }
            self.localDescription.sdp = sections.join('');
            var transceivers = self._pendingOffer ? self._pendingOffer :
                self.transceivers;
            var complete = transceivers.every(function(transceiver) {
              return transceiver.iceGatherer &&
                  transceiver.iceGatherer.state === 'completed';
            });

            // Emit candidate if localDescription is set.
            // Also emits null candidate when all gatherers are complete.
            switch (self.iceGatheringState) {
              case 'new':
                if (!end) {
                  self._localIceCandidatesBuffer.push(event);
                }
                if (end && complete) {
                  self._localIceCandidatesBuffer.push(
                      new Event('icecandidate'));
                }
                break;
              case 'gathering':
                self._emitBufferedCandidates();
                if (!end) {
                  self.dispatchEvent(event);
                  if (self.onicecandidate !== null) {
                    self.onicecandidate(event);
                  }
                }
                if (complete) {
                  self.dispatchEvent(new Event('icecandidate'));
                  if (self.onicecandidate !== null) {
                    self.onicecandidate(new Event('icecandidate'));
                  }
                  self.iceGatheringState = 'complete';
                  self._emitGatheringStateChange();
                }
                break;
              case 'complete':
                // should not happen... currently!
                break;
              default: // no-op.
                break;
            }
          };
          iceTransport.onicestatechange = function() {
            self._updateConnectionState();
          };

          var dtlsTransport = new RTCDtlsTransport(iceTransport);
          dtlsTransport.ondtlsstatechange = function() {
            self._updateConnectionState();
          };
          dtlsTransport.onerror = function() {
            // onerror does not set state to failed by itself.
            dtlsTransport.state = 'failed';
            self._updateConnectionState();
          };

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

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

    window.RTCPeerConnection.prototype.setLocalDescription =
        function(description) {
          var self = this;
          var sections;
          var sessionpart;
          if (description.type === 'offer') {
            // FIXME: What was the purpose of this empty if statement?
            // if (!this._pendingOffer) {
            // } else {
            if (this._pendingOffer) {
              // 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);
                self._pendingOffer[sdpMLineIndex].localCapabilities = caps;
              });
              this.transceivers = this._pendingOffer;
              delete this._pendingOffer;
            }
          } else if (description.type === 'answer') {
            sections = SDPUtils.splitSections(self.remoteDescription.sdp);
            sessionpart = sections.shift();
            var isIceLite = SDPUtils.matchPrefix(sessionpart,
                'a=ice-lite').length > 0;
            sections.forEach(function(mediaSection, sdpMLineIndex) {
              var transceiver = self.transceivers[sdpMLineIndex];
              var iceGatherer = transceiver.iceGatherer;
              var iceTransport = transceiver.iceTransport;
              var dtlsTransport = transceiver.dtlsTransport;
              var localCapabilities = transceiver.localCapabilities;
              var remoteCapabilities = transceiver.remoteCapabilities;

              var rejected = mediaSection.split('\n', 1)[0]
                  .split(' ', 2)[1] === '0';

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

                if (!self.usingBundle || sdpMLineIndex === 0) {
                  iceTransport.start(iceGatherer, remoteIceParameters,
                      isIceLite ? 'controlling' : 'controlled');
                  dtlsTransport.start(remoteDtlsParameters);
                }

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

                // Start the RTCRtpSender. The RTCRtpReceiver for this
                // transceiver has already been started in setRemoteDescription.
                self._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 +
                  '"');
          }

          // If a success callback was provided, emit ICE candidates after it
          // has been executed. Otherwise, emit callback after the Promise is
          // resolved.
          var hasCallback = arguments.length > 1 &&
            typeof arguments[1] === 'function';
          if (hasCallback) {
            var cb = arguments[1];
            window.setTimeout(function() {
              cb();
              if (self.iceGatheringState === 'new') {
                self.iceGatheringState = 'gathering';
                self._emitGatheringStateChange();
              }
              self._emitBufferedCandidates();
            }, 0);
          }
          var p = Promise.resolve();
          p.then(function() {
            if (!hasCallback) {
              if (self.iceGatheringState === 'new') {
                self.iceGatheringState = 'gathering';
                self._emitGatheringStateChange();
              }
              // Usually candidates will be emitted earlier.
              window.setTimeout(self._emitBufferedCandidates.bind(self), 500);
            }
          });
          return p;
        };

    window.RTCPeerConnection.prototype.setRemoteDescription =
        function(description) {
          var self = this;
          var stream = new MediaStream();
          var receiverList = [];
          var sections = SDPUtils.splitSections(description.sdp);
          var sessionpart = sections.shift();
          var isIceLite = SDPUtils.matchPrefix(sessionpart,
              'a=ice-lite').length > 0;
          this.usingBundle = SDPUtils.matchPrefix(sessionpart,
              'a=group:BUNDLE ').length > 0;
          sections.forEach(function(mediaSection, sdpMLineIndex) {
            var lines = SDPUtils.splitLines(mediaSection);
            var mline = lines[0].substr(2).split(' ');
            var kind = mline[0];
            var rejected = mline[1] === '0';
            var direction = SDPUtils.getDirection(mediaSection, sessionpart);

            var mid = SDPUtils.matchPrefix(mediaSection, 'a=mid:');
            if (mid.length) {
              mid = mid[0].substr(6);
            } else {
              mid = SDPUtils.generateIdentifier();
            }

            // Reject datachannels which are not implemented yet.
            if (kind === 'application' && mline[2] === 'DTLS/SCTP') {
              self.transceivers[sdpMLineIndex] = {
                mid: mid,
                isDatachannel: true
              };
              return;
            }

            var transceiver;
            var iceGatherer;
            var iceTransport;
            var dtlsTransport;
            var rtpSender;
            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 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) {
              cname = remoteSsrc.value;
            }

            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';
                });
            if (description.type === 'offer' && !rejected) {
              var transports = self.usingBundle && sdpMLineIndex > 0 ? {
                iceGatherer: self.transceivers[0].iceGatherer,
                iceTransport: self.transceivers[0].iceTransport,
                dtlsTransport: self.transceivers[0].dtlsTransport
              } : self._createIceAndDtlsTransports(mid, sdpMLineIndex);

              if (isComplete && (!self.usingBundle || sdpMLineIndex === 0)) {
                transports.iceTransport.setRemoteCandidates(cands);
              }

              localCapabilities = RTCRtpReceiver.getCapabilities(kind);

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

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

              if (direction === 'sendrecv' || direction === 'sendonly') {
                rtpReceiver = new RTCRtpReceiver(transports.dtlsTransport,
                    kind);

                track = rtpReceiver.track;
                receiverList.push([track, rtpReceiver]);
                // FIXME: not correct when there are multiple streams but that
                // is not currently supported in this shim.
                stream.addTrack(track);
              }

              // FIXME: look at direction.
              if (self.localStreams.length > 0 &&
                  self.localStreams[0].getTracks().length >= sdpMLineIndex) {
                var localTrack;
                if (kind === 'audio') {
                  localTrack = self.localStreams[0].getAudioTracks()[0];
                } else if (kind === 'video') {
                  localTrack = self.localStreams[0].getVideoTracks()[0];
                }
                if (localTrack) {
                  // add RTX
                  if (browserDetails.version >= 15019 && kind === 'video') {
                    sendEncodingParameters[0].rtx = {
                      ssrc: (2 * sdpMLineIndex + 2) * 1001 + 1
                    };
                  }
                  rtpSender = new RTCRtpSender(localTrack,
                      transports.dtlsTransport);
                }
              }

              self.transceivers[sdpMLineIndex] = {
                iceGatherer: transports.iceGatherer,
                iceTransport: transports.iceTransport,
                dtlsTransport: transports.dtlsTransport,
                localCapabilities: localCapabilities,
                remoteCapabilities: remoteCapabilities,
                rtpSender: rtpSender,
                rtpReceiver: rtpReceiver,
                kind: kind,
                mid: mid,
                cname: cname,
                sendEncodingParameters: sendEncodingParameters,
                recvEncodingParameters: recvEncodingParameters
              };
              // Start the RTCRtpReceiver now. The RTPSender is started in
              // setLocalDescription.
              self._transceive(self.transceivers[sdpMLineIndex],
                  false,
                  direction === 'sendrecv' || direction === 'sendonly');
            } else if (description.type === 'answer' && !rejected) {
              transceiver = self.transceivers[sdpMLineIndex];
              iceGatherer = transceiver.iceGatherer;
              iceTransport = transceiver.iceTransport;
              dtlsTransport = transceiver.dtlsTransport;
              rtpSender = transceiver.rtpSender;
              rtpReceiver = transceiver.rtpReceiver;
              sendEncodingParameters = transceiver.sendEncodingParameters;
              localCapabilities = transceiver.localCapabilities;

              self.transceivers[sdpMLineIndex].recvEncodingParameters =
                  recvEncodingParameters;
              self.transceivers[sdpMLineIndex].remoteCapabilities =
                  remoteCapabilities;
              self.transceivers[sdpMLineIndex].cname = cname;

              if ((isIceLite || isComplete) && cands.length) {
                iceTransport.setRemoteCandidates(cands);
              }
              if (!self.usingBundle || sdpMLineIndex === 0) {
                iceTransport.start(iceGatherer, remoteIceParameters,
                    'controlling');
                dtlsTransport.start(remoteDtlsParameters);
              }

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

              if (rtpReceiver &&
                  (direction === 'sendrecv' || direction === 'sendonly')) {
                track = rtpReceiver.track;
                receiverList.push([track, rtpReceiver]);
                stream.addTrack(track);
              } else {
                // FIXME: actually the receiver should be created later.
                delete transceiver.rtpReceiver;
              }
            }
          });

          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 +
                  '"');
          }
          if (stream.getTracks().length) {
            self.remoteStreams.push(stream);
            window.setTimeout(function() {
              var event = new Event('addstream');
              event.stream = stream;
              self.dispatchEvent(event);
              if (self.onaddstream !== null) {
                window.setTimeout(function() {
                  self.onaddstream(event);
                }, 0);
              }

              receiverList.forEach(function(item) {
                var track = item[0];
                var receiver = item[1];
                var trackEvent = new Event('track');
                trackEvent.track = track;
                trackEvent.receiver = receiver;
                trackEvent.streams = [stream];
                self.dispatchEvent(trackEvent);
                if (self.ontrack !== null) {
                  window.setTimeout(function() {
                    self.ontrack(trackEvent);
                  }, 0);
                }
              });
            }, 0);
          }
          if (arguments.length > 1 && typeof arguments[1] === 'function') {
            window.setTimeout(arguments[1], 0);
          }
          return Promise.resolve();
        };

    window.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._updateSignalingState('closed');
    };

    // Update the signaling state.
    window.RTCPeerConnection.prototype._updateSignalingState =
        function(newState) {
          this.signalingState = newState;
          var event = new Event('signalingstatechange');
          this.dispatchEvent(event);
          if (this.onsignalingstatechange !== null) {
            this.onsignalingstatechange(event);
          }
        };

    // Determine whether to fire the negotiationneeded event.
    window.RTCPeerConnection.prototype._maybeFireNegotiationNeeded =
        function() {
          // Fire away (for now).
          var event = new Event('negotiationneeded');
          this.dispatchEvent(event);
          if (this.onnegotiationneeded !== null) {
            this.onnegotiationneeded(event);
          }
        };

    // Update the connection state.
    window.RTCPeerConnection.prototype._updateConnectionState = function() {
      var self = this;
      var newState;
      var states = {
        'new': 0,
        closed: 0,
        connecting: 0,
        checking: 0,
        connected: 0,
        completed: 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 !== self.iceConnectionState) {
        self.iceConnectionState = newState;
        var event = new Event('iceconnectionstatechange');
        this.dispatchEvent(event);
        if (this.oniceconnectionstatechange !== null) {
          this.oniceconnectionstatechange(event);
        }
      }
    };

    window.RTCPeerConnection.prototype.createOffer = function() {
      var self = this;
      if (this._pendingOffer) {
        throw new Error('createOffer called while there is a pending offer.');
      }
      var offerOptions;
      if (arguments.length === 1 && typeof arguments[0] !== 'function') {
        offerOptions = arguments[0];
      } else if (arguments.length === 3) {
        offerOptions = arguments[2];
      }

      var tracks = [];
      var numAudioTracks = 0;
      var numVideoTracks = 0;
      // Default to sendrecv.
      if (this.localStreams.length) {
        numAudioTracks = this.localStreams[0].getAudioTracks().length;
        numVideoTracks = this.localStreams[0].getVideoTracks().length;
      }
      // Determine number of audio and video tracks we need to send/recv.
      if (offerOptions) {
        // Reject Chrome legacy constraints.
        if (offerOptions.mandatory || offerOptions.optional) {
          throw new TypeError(
              'Legacy mandatory/optional constraints not supported.');
        }
        if (offerOptions.offerToReceiveAudio !== undefined) {
          numAudioTracks = offerOptions.offerToReceiveAudio;
        }
        if (offerOptions.offerToReceiveVideo !== undefined) {
          numVideoTracks = offerOptions.offerToReceiveVideo;
        }
      }
      if (this.localStreams.length) {
        // Push local streams.
        this.localStreams[0].getTracks().forEach(function(track) {
          tracks.push({
            kind: track.kind,
            track: track,
            wantReceive: track.kind === 'audio' ?
                numAudioTracks > 0 : numVideoTracks > 0
          });
          if (track.kind === 'audio') {
            numAudioTracks--;
          } else if (track.kind === 'video') {
            numVideoTracks--;
          }
        });
      }
      // Create M-lines for recvonly streams.
      while (numAudioTracks > 0 || numVideoTracks > 0) {
        if (numAudioTracks > 0) {
          tracks.push({
            kind: 'audio',
            wantReceive: true
          });
          numAudioTracks--;
        }
        if (numVideoTracks > 0) {
          tracks.push({
            kind: 'video',
            wantReceive: true
          });
          numVideoTracks--;
        }
      }
      // reorder tracks
      tracks = sortTracks(tracks);

      var sdp = SDPUtils.writeSessionBoilerplate();
      var transceivers = [];
      tracks.forEach(function(mline, sdpMLineIndex) {
        // For each track, create an ice gatherer, ice transport,
        // dtls transport, potentially rtpsender and rtpreceiver.
        var track = mline.track;
        var kind = mline.kind;
        var mid = SDPUtils.generateIdentifier();

        var transports = self.usingBundle && sdpMLineIndex > 0 ? {
          iceGatherer: transceivers[0].iceGatherer,
          iceTransport: transceivers[0].iceTransport,
          dtlsTransport: transceivers[0].dtlsTransport
        } : self._createIceAndDtlsTransports(mid, sdpMLineIndex);

        var localCapabilities = RTCRtpSender.getCapabilities(kind);
        // filter RTX until additional stuff needed for RTX is implemented
        // in adapter.js
        if (browserDetails.version < 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';
          }
        });

        var rtpSender;
        var rtpReceiver;

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

        if (mline.wantReceive) {
          rtpReceiver = new RTCRtpReceiver(transports.dtlsTransport, kind);
        }

        transceivers[sdpMLineIndex] = {
          iceGatherer: transports.iceGatherer,
          iceTransport: transports.iceTransport,
          dtlsTransport: transports.dtlsTransport,
          localCapabilities: localCapabilities,
          remoteCapabilities: null,
          rtpSender: rtpSender,
          rtpReceiver: rtpReceiver,
          kind: kind,
          mid: mid,
          sendEncodingParameters: sendEncodingParameters,
          recvEncodingParameters: null
        };
      });
      if (this.usingBundle) {
        sdp += 'a=group:BUNDLE ' + transceivers.map(function(t) {
          return t.mid;
        }).join(' ') + '\r\n';
      }
      tracks.forEach(function(mline, sdpMLineIndex) {
        var transceiver = transceivers[sdpMLineIndex];
        sdp += SDPUtils.writeMediaSection(transceiver,
            transceiver.localCapabilities, 'offer', self.localStreams[0]);
      });

      this._pendingOffer = transceivers;
      var desc = new RTCSessionDescription({
        type: 'offer',
        sdp: sdp
      });
      if (arguments.length && typeof arguments[0] === 'function') {
        window.setTimeout(arguments[0], 0, desc);
      }
      return Promise.resolve(desc);
    };

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

      var sdp = SDPUtils.writeSessionBoilerplate();
      if (this.usingBundle) {
        sdp += 'a=group:BUNDLE ' + this.transceivers.map(function(t) {
          return t.mid;
        }).join(' ') + '\r\n';
      }
      this.transceivers.forEach(function(transceiver) {
        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;
        }
        // Calculate intersection of capabilities.
        var commonCapabilities = self._getCommonCapabilities(
            transceiver.localCapabilities,
            transceiver.remoteCapabilities);

        sdp += SDPUtils.writeMediaSection(transceiver, commonCapabilities,
            'answer', self.localStreams[0]);
      });

      var desc = new RTCSessionDescription({
        type: 'answer',
        sdp: sdp
      });
      if (arguments.length && typeof arguments[0] === 'function') {
        window.setTimeout(arguments[0], 0, desc);
      }
      return Promise.resolve(desc);
    };

    window.RTCPeerConnection.prototype.addIceCandidate = function(candidate) {
      if (!candidate) {
        for (var j = 0; j < this.transceivers.length; j++) {
          this.transceivers[j].iceTransport.addRemoteCandidate({});
          if (this.usingBundle) {
            return Promise.resolve();
          }
        }
      } else {
        var mLineIndex = candidate.sdpMLineIndex;
        if (candidate.sdpMid) {
          for (var i = 0; i < this.transceivers.length; i++) {
            if (this.transceivers[i].mid === candidate.sdpMid) {
              mLineIndex = i;
              break;
            }
          }
        }
        var transceiver = this.transceivers[mLineIndex];
        if (transceiver) {
          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 !== '1') {
            return Promise.resolve();
          }
          transceiver.iceTransport.addRemoteCandidate(cand);

          // update the remoteDescription.
          var sections = SDPUtils.splitSections(this.remoteDescription.sdp);
          sections[mLineIndex + 1] += (cand.type ? candidate.candidate.trim()
              : 'a=end-of-candidates') + '\r\n';
          this.remoteDescription.sdp = sections.join('');
        }
      }
      if (arguments.length > 1 && typeof arguments[1] === 'function') {
        window.setTimeout(arguments[1], 0);
      }
      return Promise.resolve();
    };

    window.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 cb = arguments.length > 1 && typeof arguments[1] === 'function' &&
          arguments[1];
      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]);
            });
          });
          if (cb) {
            window.setTimeout(cb, 0, results);
          }
          resolve(results);
        });
      });
    };
  }
};

// Expose public methods.
module.exports = {
  shimPeerConnection: edgeShim.shimPeerConnection,
  shimGetUserMedia: require('./getusermedia')
};

},{"../utils":10,"./getusermedia":6,"sdp":1}],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';

// Expose public methods.
module.exports = function() {
  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));
    });
  };
};

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

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

var firefoxShim = {
  shimOnTrack: function() {
    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.streams = [e.stream];
              this.dispatchEvent(event);
            }.bind(this));
          }.bind(this));
        }
      });
    }
  },

  shimSourceObject: function() {
    // 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() {
    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 mozRTCPeerConnection(pcConfig, pcConstraints);
      };
      window.RTCPeerConnection.prototype = mozRTCPeerConnection.prototype;

      // wrap static methods. Currently just generateCertificate.
      if (mozRTCPeerConnection.generateCertificate) {
        Object.defineProperty(window.RTCPeerConnection, 'generateCertificate', {
          get: function() {
            return mozRTCPeerConnection.generateCertificate;
          }
        });
      }

      window.RTCSessionDescription = mozRTCSessionDescription;
      window.RTCIceCandidate = mozRTCIceCandidate;
    }

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

    // support for addIceCandidate(null or undefined)
    var nativeAddIceCandidate =
        RTCPeerConnection.prototype.addIceCandidate;
    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 = RTCPeerConnection.prototype.getStats;
    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);
    };
  }
};

// Expose public methods.
module.exports = {
  shimOnTrack: firefoxShim.shimOnTrack,
  shimSourceObject: firefoxShim.shimSourceObject,
  shimPeerConnection: firefoxShim.shimPeerConnection,
  shimGetUserMedia: require('./getusermedia')
};

},{"../utils":10,"./getusermedia":8}],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 logging = require('../utils').log;
var browserDetails = require('../utils').browserDetails;

// Expose public methods.
module.exports = function() {
  var shimError_ = function(e) {
    return {
      name: {
        SecurityError: 'NotAllowedError',
        PermissionDeniedError: '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));
      });
    };
  }
  navigator.getUserMedia = function(constraints, onSuccess, onError) {
    if (browserDetails.version < 44) {
      return getUserMedia_(constraints, onSuccess, onError);
    }
    // Replace Firefox 44+'s deprecation warning with unprefixed version.
    console.warn('navigator.getUserMedia has been replaced by ' +
                 'navigator.mediaDevices.getUserMedia');
    navigator.mediaDevices.getUserMedia(constraints).then(onSuccess, onError);
  };
};

},{"../utils":10}],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.
 */
'use strict';
var safariShim = {
  // TODO: DrAlex, should be here, double check against LayoutTests
  // shimOnTrack: function() { },

  // TODO: once the back-end for the mac port is done, add.
  // TODO: check for webkitGTK+
  // shimPeerConnection: function() { },

  shimGetUserMedia: function() {
    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);
      }
    }
  }
};

// Expose public methods.
module.exports = {
  shimGetUserMedia: safariShim.shimGetUserMedia
  // TODO
  // shimOnTrack: safariShim.shimOnTrack,
  // shimPeerConnection: safariShim.shimPeerConnection
};

},{}],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 logDisabled_ = true;

// Utility methods.
var utils = {
  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';
  },

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

  /**
   * 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.
   */
  extractVersion: function(uastring, expr, pos) {
    var match = uastring.match(expr);
    return match && match.length >= pos && parseInt(match[pos], 10);
  },

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

    // Firefox.
    if (navigator.mozGetUserMedia) {
      result.browser = 'firefox';
      result.version = this.extractVersion(navigator.userAgent,
          /Firefox\/(\d+)\./, 1);
    } else if (navigator.webkitGetUserMedia) {
      // Chrome, Chromium, Webview, Opera, all use the chrome shim for now
      if (window.webkitRTCPeerConnection) {
        result.browser = 'chrome';
        result.version = this.extractVersion(navigator.userAgent,
          /Chrom(e|ium)\/(\d+)\./, 2);
      } else { // Safari (in an unpublished version) or unknown webkit-based.
        if (navigator.userAgent.match(/Version\/(\d+).(\d+)/)) {
          result.browser = 'safari';
          result.version = this.extractVersion(navigator.userAgent,
            /AppleWebKit\/(\d+)\./, 1);
        } else { // unknown webkit-based browser.
          result.browser = 'Unsupported webkit-based browser ' +
              'with GUM support but no WebRTC support.';
          return result;
        }
      }
    } else if (navigator.mediaDevices &&
        navigator.userAgent.match(/Edge\/(\d+).(\d+)$/)) { // Edge.
      result.browser = 'edge';
      result.version = this.extractVersion(navigator.userAgent,
          /Edge\/(\d+).(\d+)$/, 2);
    } else if (navigator.mediaDevices &&
        navigator.userAgent.match(/AppleWebKit\/(\d+)\./)) {
        // Safari, with webkitGetUserMedia removed.
      result.browser = 'safari';
      result.version = this.extractVersion(navigator.userAgent,
          /AppleWebKit\/(\d+)\./, 1);
    } else { // Default fallthrough: not supported.
      result.browser = 'Not a supported browser.';
      return result;
    }

    return result;
  },

  // shimCreateObjectURL must be called before shimSourceObject to avoid loop.

  shimCreateObjectURL: function() {
    if (!(typeof window === 'object' && window.HTMLMediaElement &&
          'srcObject' in window.HTMLMediaElement.prototype)) {
      // 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);
        console.log('URL.createObjectURL(stream) is deprecated! ' +
                    'Use elem.srcObject = stream instead!');
        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 = HTMLMediaElement.prototype.setAttribute;
    HTMLMediaElement.prototype.setAttribute = function() {
      if (arguments.length === 2 &&
          ('' + arguments[0]).toLowerCase() === 'src') {
        this.srcObject = streams.get(arguments[1]) || null;
      }
      return nativeSetAttribute.apply(this, arguments);
    };
  }
};

// Export.
module.exports = {
  log: utils.log,
  disableLog: utils.disableLog,
  browserDetails: utils.detectBrowser(),
  extractVersion: utils.extractVersion,
  shimCreateObjectURL: utils.shimCreateObjectURL,
  detectBrowser: utils.detectBrowser.bind(utils)
};

},{}]},{},[2])(2)
});