File: source/stream-sdp.js

  1. /**
  2.  * Function that modifies the session description to configure settings for OPUS audio codec.
  3.  * @method _setSDPCodecParams
  4.  * @private
  5.  * @for Skylink
  6.  * @since 0.6.16
  7.  */
  8. Skylink.prototype._setSDPCodecParams = function(targetMid, sessionDescription) {
  9.   var self = this;
  10.  
  11.   var parseFn = function (type, codecName, samplingRate, settings) {
  12.     var mLine = sessionDescription.sdp.match(new RegExp('m=' + type + '\ .*\r\n', 'gi'));
  13.     // Find the m= line
  14.     if (Array.isArray(mLine) && mLine.length > 0) {
  15.       var codecsList = sessionDescription.sdp.match(new RegExp('a=rtpmap:.*\ ' + codecName + '\/' +
  16.         (samplingRate ? samplingRate + (type === 'audio' ? '[\/]*.*' : '.*') : '.*') + '\r\n', 'gi'));
  17.       // Get the list of codecs related to it
  18.       if (Array.isArray(codecsList) && codecsList.length > 0) {
  19.         for (var i = 0; i < codecsList.length; i++) {
  20.           var payload = (codecsList[i].split('a=rtpmap:')[1] || '').split(' ')[0];
  21.           if (!payload) {
  22.             continue;
  23.           }
  24.           var fmtpLine = sessionDescription.sdp.match(new RegExp('a=fmtp:' + payload + '\ .*\r\n', 'gi'));
  25.           var updatedFmtpLine = 'a=fmtp:' + payload + ' ';
  26.           var addedKeys = [];
  27.           // Check if a=fmtp: line exists
  28.           if (Array.isArray(fmtpLine) && fmtpLine.length > 0) {
  29.             var fmtpParts = (fmtpLine[0].split('a=fmtp:' + payload + ' ')[1] || '').replace(
  30.               / /g, '').replace(/\r\n/g, '').split(';');
  31.             for (var j = 0; j < fmtpParts.length; j++) {
  32.               if (!fmtpParts[j]) {
  33.                 continue;
  34.               }
  35.               var keyAndValue = fmtpParts[j].split('=');
  36.               if (settings.hasOwnProperty(keyAndValue[0])) {
  37.                 // Dont append parameter key+value if boolean and false
  38.                 updatedFmtpLine += typeof settings[keyAndValue[0]] === 'boolean' ? (settings[keyAndValue[0]] ?
  39.                   keyAndValue[0] + '=1;' : '') : keyAndValue[0] + '=' + settings[keyAndValue[0]] + ';';
  40.               } else {
  41.                 updatedFmtpLine += fmtpParts[j] + ';';
  42.               }
  43.               addedKeys.push(keyAndValue[0]);
  44.             }
  45.             sessionDescription.sdp = sessionDescription.sdp.replace(fmtpLine[0], '');
  46.           }
  47.           for (var key in settings) {
  48.             if (settings.hasOwnProperty(key) && addedKeys.indexOf(key) === -1) {
  49.               // Dont append parameter key+value if boolean and false
  50.               updatedFmtpLine += typeof settings[key] === 'boolean' ? (settings[key] ? key + '=1;' : '') :
  51.                 key + '=' + settings[key] + ';';
  52.               addedKeys.push(key);
  53.             }
  54.           }
  55.           if (updatedFmtpLine !== 'a=fmtp:' + payload + ' ') {
  56.             sessionDescription.sdp = sessionDescription.sdp.replace(codecsList[i], codecsList[i] + updatedFmtpLine + '\r\n');
  57.           }
  58.         }
  59.       }
  60.     }
  61.   };
  62.  
  63.   // Set audio codecs -> OPUS
  64.   // RFC: https://tools.ietf.org/html/draft-ietf-payload-rtp-opus-11
  65.   parseFn('audio', self.AUDIO_CODEC.OPUS, 48000, (function () {
  66.     var opusOptions = {};
  67.     var audioSettings = self._streams.screenshare ? self._streams.screenshare.settings.audio :
  68.       (self._streams.userMedia ? self._streams.userMedia.settings.audio : {});
  69.     audioSettings = audioSettings && typeof audioSettings === 'object' ? audioSettings : {};
  70.     if (typeof self._initOptions.codecParams.audio.opus.stereo === 'boolean') {
  71.       opusOptions.stereo = self._initOptions.codecParams.audio.opus.stereo;
  72.     } else if (typeof audioSettings.stereo === 'boolean') {
  73.       opusOptions.stereo = audioSettings.stereo;
  74.     }
  75.     if (typeof self._initOptions.codecParams.audio.opus['sprop-stereo'] === 'boolean') {
  76.       opusOptions['sprop-stereo'] = self._initOptions.codecParams.audio.opus['sprop-stereo'];
  77.     } else if (typeof audioSettings.stereo === 'boolean') {
  78.       opusOptions['sprop-stereo'] = audioSettings.stereo;
  79.     }
  80.     if (typeof self._initOptions.codecParams.audio.opus.usedtx === 'boolean') {
  81.       opusOptions.usedtx = self._initOptions.codecParams.audio.opus.usedtx;
  82.     } else if (typeof audioSettings.usedtx === 'boolean') {
  83.       opusOptions.usedtx = audioSettings.usedtx;
  84.     }
  85.     if (typeof self._initOptions.codecParams.audio.opus.useinbandfec === 'boolean') {
  86.       opusOptions.useinbandfec = self._initOptions.codecParams.audio.opus.useinbandfec;
  87.     } else if (typeof audioSettings.useinbandfec === 'boolean') {
  88.       opusOptions.useinbandfec = audioSettings.useinbandfec;
  89.     }
  90.     if (typeof self._initOptions.codecParams.audio.opus.maxplaybackrate === 'number') {
  91.       opusOptions.maxplaybackrate = self._initOptions.codecParams.audio.opus.maxplaybackrate;
  92.     } else if (typeof audioSettings.maxplaybackrate === 'number') {
  93.       opusOptions.maxplaybackrate = audioSettings.maxplaybackrate;
  94.     }
  95.     if (typeof self._initOptions.codecParams.audio.opus.minptime === 'number') {
  96.       opusOptions.minptime = self._initOptions.codecParams.audio.opus.minptime;
  97.     } else if (typeof audioSettings.minptime === 'number') {
  98.       opusOptions.minptime = audioSettings.minptime;
  99.     }
  100.     // Possible future params: sprop-maxcapturerate, maxaveragebitrate, sprop-stereo, cbr
  101.     // NOT recommended: maxptime, ptime, rate, minptime
  102.     return opusOptions;
  103.   })());
  104.  
  105.   // RFC: https://tools.ietf.org/html/rfc4733
  106.   // Future: Set telephone-event: 100 0-15,66,70
  107.  
  108.   // RFC: https://tools.ietf.org/html/draft-ietf-payload-vp8-17
  109.   // Set video codecs -> VP8
  110.   parseFn('video', self.VIDEO_CODEC.VP8, null, (function () {
  111.     var vp8Options = {};
  112.     // NOT recommended: max-fr, max-fs (all are codec decoder capabilities)
  113.     if (typeof self._initOptions.codecParams.video.vp8.maxFr === 'number') {
  114.       vp8Options['max-fr'] = self._initOptions.codecParams.video.vp8.maxFr;
  115.     }
  116.     if (typeof self._initOptions.codecParams.video.vp8.maxFs === 'number') {
  117.       vp8Options['max-fs'] = self._initOptions.codecParams.video.vp8.maxFs;
  118.     }
  119.     return vp8Options;
  120.   })());
  121.  
  122.   // RFC: https://tools.ietf.org/html/draft-ietf-payload-vp9-02
  123.   // Set video codecs -> VP9
  124.   parseFn('video', self.VIDEO_CODEC.VP9, null, (function () {
  125.     var vp9Options = {};
  126.     // NOT recommended: max-fr, max-fs (all are codec decoder capabilities)
  127.     if (typeof self._initOptions.codecParams.video.vp9.maxFr === 'number') {
  128.       vp9Options['max-fr'] = self._initOptions.codecParams.video.vp9.maxFr;
  129.     }
  130.     if (typeof self._initOptions.codecParams.video.vp9.maxFs === 'number') {
  131.       vp9Options['max-fs'] = self._initOptions.codecParams.video.vp9.maxFs;
  132.     }
  133.     return vp9Options;
  134.   })());
  135.  
  136.   // RFC: https://tools.ietf.org/html/rfc6184
  137.   // Set the video codecs -> H264
  138.   parseFn('video', self.VIDEO_CODEC.H264, null, (function () {
  139.     var h264Options = {};
  140.     if (typeof self._initOptions.codecParams.video.h264.levelAsymmetryAllowed === 'string') {
  141.       h264Options['profile-level-id'] = self._initOptions.codecParams.video.h264.profileLevelId;
  142.     }
  143.     if (typeof self._initOptions.codecParams.video.h264.levelAsymmetryAllowed === 'boolean') {
  144.       h264Options['level-asymmetry-allowed'] = self._initOptions.codecParams.video.h264.levelAsymmetryAllowed;
  145.     }
  146.     if (typeof self._initOptions.codecParams.video.h264.packetizationMode === 'boolean') {
  147.       h264Options['packetization-mode'] = self._initOptions.codecParams.video.h264.packetizationMode;
  148.     }
  149.     // Possible future params (remove if they are decoder/encoder capabilities or info):
  150.     //   max-recv-level, max-mbps, max-smbps, max-fs, max-cpb, max-dpb, max-br,
  151.     //   max-mbps, max-smbps, max-fs, max-cpb, max-dpb, max-br, redundant-pic-cap, sprop-parameter-sets,
  152.     //   sprop-level-parameter-sets, use-level-src-parameter-sets, in-band-parameter-sets,
  153.     //   sprop-interleaving-depth, sprop-deint-buf-req, deint-buf-cap, sprop-init-buf-time,
  154.     //   sprop-max-don-diff, max-rcmd-nalu-size, sar-understood, sar-supported
  155.     //   NOT recommended: profile-level-id (WebRTC uses "42e00a" for the moment)
  156.     //   https://bugs.chromium.org/p/chromium/issues/detail?id=645599
  157.     return h264Options;
  158.   })());
  159.  
  160.   return sessionDescription.sdp;
  161. };
  162.  
  163. /**
  164.  * Function that modifies the session description to limit the maximum sending bandwidth.
  165.  * Setting this may not necessarily work in Firefox.
  166.  * @method _setSDPBitrate
  167.  * @private
  168.  * @for Skylink
  169.  * @since 0.5.10
  170.  */
  171. Skylink.prototype._setSDPBitrate = function(targetMid, sessionDescription) {
  172.   var sdpLines = sessionDescription.sdp.split('\r\n');
  173.   var parseFn = function (type, bw) {
  174.     var mLineType = type;
  175.     var mLineIndex = -1;
  176.     var cLineIndex = -1;
  177.  
  178.     if (type === 'data') {
  179.       mLineType = 'application';
  180.     }
  181.  
  182.     for (var i = 0; i < sdpLines.length; i++) {
  183.       if (sdpLines[i].indexOf('m=' + mLineType) === 0) {
  184.         mLineIndex = i;
  185.       } else if (mLineIndex > 0) {
  186.         if (sdpLines[i].indexOf('m=') === 0) {
  187.           break;
  188.         }
  189.  
  190.         if (sdpLines[i].indexOf('c=') === 0) {
  191.           cLineIndex = i;
  192.         // Remove previous b:AS settings
  193.         } else if (sdpLines[i].indexOf('b=AS:') === 0 || sdpLines[i].indexOf('b:TIAS:') === 0) {
  194.           sdpLines.splice(i, 1);
  195.           i--;
  196.         }
  197.       }
  198.     }
  199.  
  200.     if (!(typeof bw === 'number' && bw > 0)) {
  201.       log.warn([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Not limiting "' + type + '" bandwidth']);
  202.       return;
  203.     }
  204.  
  205.     if (cLineIndex === -1) {
  206.       log.error([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Failed setting "' +
  207.         type + '" bandwidth as c-line is missing.']);
  208.       return;
  209.     }
  210.  
  211.     // Follow RFC 4566, that the b-line should follow after c-line.
  212.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Limiting maximum sending "' + type + '" bandwidth ->'], bw);
  213.     sdpLines.splice(cLineIndex + 1, 0, window.webrtcDetectedBrowser === 'firefox' ? 'b=TIAS:' + (bw * 1000 *
  214.     (window.webrtcDetectedVersion > 52 && window.webrtcDetectedVersion < 55 ? 1000 : 1)).toFixed(0) : 'b=AS:' + bw);
  215.   };
  216.  
  217.   var bASAudioBw = this._streamsBandwidthSettings.bAS.audio;
  218.   var bASVideoBw = this._streamsBandwidthSettings.bAS.video;
  219.   var bASDataBw = this._streamsBandwidthSettings.bAS.data;
  220.   var googleXMinBw = this._streamsBandwidthSettings.googleX.min;
  221.   var googleXMaxBw = this._streamsBandwidthSettings.googleX.max;
  222.  
  223.   if (this._peerCustomConfigs[targetMid]) {
  224.     if (this._peerCustomConfigs[targetMid].bandwidth &&
  225.       typeof this._peerCustomConfigs[targetMid].bandwidth === 'object') {
  226.       if (typeof this._peerCustomConfigs[targetMid].bandwidth.audio === 'number') {
  227.         bASAudioBw = this._peerCustomConfigs[targetMid].bandwidth.audio;
  228.       }
  229.       if (typeof this._peerCustomConfigs[targetMid].bandwidth.video === 'number') {
  230.         bASVideoBw = this._peerCustomConfigs[targetMid].bandwidth.video;
  231.       }
  232.       if (typeof this._peerCustomConfigs[targetMid].bandwidth.data === 'number') {
  233.         bASDataBw = this._peerCustomConfigs[targetMid].bandwidth.data;
  234.       }
  235.     }
  236.     if (this._peerCustomConfigs[targetMid].googleXBandwidth &&
  237.       typeof this._peerCustomConfigs[targetMid].googleXBandwidth === 'object') {
  238.       if (typeof this._peerCustomConfigs[targetMid].googleXBandwidth.min === 'number') {
  239.         googleXMinBw = this._peerCustomConfigs[targetMid].googleXBandwidth.min;
  240.       }
  241.       if (typeof this._peerCustomConfigs[targetMid].googleXBandwidth.max === 'number') {
  242.         googleXMaxBw = this._peerCustomConfigs[targetMid].googleXBandwidth.max;
  243.       }
  244.     }
  245.   }
  246.  
  247.   parseFn('audio', bASAudioBw);
  248.   parseFn('video', bASVideoBw);
  249.   parseFn('data', bASDataBw);
  250.  
  251.   // Sets the experimental google bandwidth
  252.   if ((typeof googleXMinBw === 'number') || (typeof googleXMaxBw === 'number')) {
  253.     var codec = null;
  254.     var codecRtpMapLineIndex = -1;
  255.     var codecFmtpLineIndex = -1;
  256.  
  257.     for (var j = 0; j < sdpLines.length; j++) {
  258.       if (sdpLines[j].indexOf('m=video') === 0) {
  259.         codec = sdpLines[j].split(' ')[3];
  260.       } else if (codec) {
  261.         if (sdpLines[j].indexOf('m=') === 0) {
  262.           break;
  263.         }
  264.  
  265.         if (sdpLines[j].indexOf('a=rtpmap:' + codec + ' ') === 0) {
  266.           codecRtpMapLineIndex = j;
  267.         } else if (sdpLines[j].indexOf('a=fmtp:' + codec + ' ') === 0) {
  268.           sdpLines[j] = sdpLines[j].replace(/x-google-(min|max)-bitrate=[0-9]*[;]*/gi, '');
  269.           codecFmtpLineIndex = j;
  270.           break;
  271.         }
  272.       }
  273.     }
  274.  
  275.     if (codecRtpMapLineIndex > -1) {
  276.       var xGoogleParams = '';
  277.  
  278.       if (typeof googleXMinBw === 'number') {
  279.         xGoogleParams += 'x-google-min-bitrate=' + googleXMinBw + ';';
  280.       }
  281.  
  282.       if (typeof googleXMaxBw === 'number') {
  283.         xGoogleParams += 'x-google-max-bitrate=' + googleXMaxBw + ';';
  284.       }
  285.  
  286.       log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Limiting x-google-bitrate ->'], xGoogleParams);
  287.  
  288.       if (codecFmtpLineIndex > -1) {
  289.         sdpLines[codecFmtpLineIndex] += (sdpLines[codecFmtpLineIndex].split(' ')[1] ? ';' : '') + xGoogleParams;
  290.       } else {
  291.         sdpLines.splice(codecRtpMapLineIndex + 1, 0, 'a=fmtp:' + codec + ' ' + xGoogleParams);
  292.       }
  293.     }
  294.   }
  295.  
  296.   return sdpLines.join('\r\n');
  297. };
  298.  
  299. /**
  300.  * Function that modifies the session description to set the preferred audio/video codec.
  301.  * @method _setSDPCodec
  302.  * @private
  303.  * @for Skylink
  304.  * @since 0.6.16
  305.  */
  306. Skylink.prototype._setSDPCodec = function(targetMid, sessionDescription, overrideSettings) {
  307.   var self = this;
  308.   var parseFn = function (type, codecSettings) {
  309.     var codec = typeof codecSettings === 'object' ? codecSettings.codec : codecSettings;
  310.     var samplingRate = typeof codecSettings === 'object' ? codecSettings.samplingRate : null;
  311.     var channels = typeof codecSettings === 'object' ? codecSettings.channels : null;
  312.  
  313.     if (codec === self[type === 'audio' ? 'AUDIO_CODEC' : 'VIDEO_CODEC'].AUTO) {
  314.       log.warn([targetMid, 'RTCSessionDesription', sessionDescription.type,
  315.         'Not preferring any codec for "' + type + '" streaming. Using browser selection.']);
  316.       return;
  317.     }
  318.  
  319.     var mLine = sessionDescription.sdp.match(new RegExp('m=' + type + ' .*\r\n', 'gi'));
  320.  
  321.     if (!(Array.isArray(mLine) && mLine.length > 0)) {
  322.       log.error([targetMid, 'RTCSessionDesription', sessionDescription.type,
  323.         'Not preferring any codec for "' + type + '" streaming as m= line is not found.']);
  324.       return;
  325.     }
  326.  
  327.     var setLineFn = function (codecsList, isSROk, isChnlsOk) {
  328.       if (Array.isArray(codecsList) && codecsList.length > 0) {
  329.         if (!isSROk) {
  330.           samplingRate = null;
  331.         }
  332.         if (!isChnlsOk) {
  333.           channels = null;
  334.         }
  335.         log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Preferring "' +
  336.           codec + '" (samplingRate: ' + (samplingRate || 'n/a') + ', channels: ' +
  337.           (channels || 'n/a') + ') for "' + type + '" streaming.']);
  338.  
  339.         var line = mLine[0];
  340.         var lineParts = line.replace('\r\n', '').split(' ');
  341.         // Set the m=x x UDP/xxx
  342.         line = lineParts[0] + ' ' + lineParts[1] + ' ' + lineParts[2] + ' ';
  343.         // Remove them to leave the codecs only
  344.         lineParts.splice(0, 3);
  345.         // Loop for the codecs list to append first
  346.         for (var i = 0; i < codecsList.length; i++) {
  347.           var parts = (codecsList[i].split('a=rtpmap:')[1] || '').split(' ');
  348.           if (parts.length < 2) {
  349.             continue;
  350.           }
  351.           line += parts[0] + ' ';
  352.         }
  353.         // Loop for later fallback codecs to append
  354.         for (var j = 0; j < lineParts.length; j++) {
  355.           if (line.indexOf(' ' + lineParts[j]) > 0) {
  356.             lineParts.splice(j, 1);
  357.             j--;
  358.           } else if (sessionDescription.sdp.match(new RegExp('a=rtpmap:' + lineParts[j] +
  359.             '\ ' + codec + '/.*\r\n', 'gi'))) {
  360.             line += lineParts[j] + ' ';
  361.             lineParts.splice(j, 1);
  362.             j--;
  363.           }
  364.         }
  365.         // Append the rest of the codecs
  366.         line += lineParts.join(' ') + '\r\n';
  367.         sessionDescription.sdp = sessionDescription.sdp.replace(mLine[0], line);
  368.         return true;
  369.       }
  370.     };
  371.  
  372.     // If samplingRate & channels
  373.     if (samplingRate) {
  374.       if (type === 'audio' && channels && setLineFn(sessionDescription.sdp.match(new RegExp('a=rtpmap:.*\ ' +
  375.         codec + '\/' + samplingRate + (channels === 1 ? '[\/1]*' : '\/' + channels) + '\r\n', 'gi')), true, true)) {
  376.         return;
  377.       } else if (setLineFn(sessionDescription.sdp.match(new RegExp('a=rtpmap:.*\ ' + codec + '\/' +
  378.         samplingRate + '[\/]*.*\r\n', 'gi')), true)) {
  379.         return;
  380.       }
  381.     }
  382.     if (type === 'audio' && channels && setLineFn(sessionDescription.sdp.match(new RegExp('a=rtpmap:.*\ ' +
  383.       codec + '\/.*\/' + channels + '\r\n', 'gi')), false, true)) {
  384.       return;
  385.     }
  386.  
  387.     setLineFn(sessionDescription.sdp.match(new RegExp('a=rtpmap:.*\ ' + codec + '\/.*\r\n', 'gi')));
  388.   };
  389.  
  390.   parseFn('audio', overrideSettings ? overrideSettings.audio : self._initOptions.audioCodec);
  391.   parseFn('video', overrideSettings ? overrideSettings.video : self._initOptions.videoCodec);
  392.  
  393.   return sessionDescription.sdp;
  394. };
  395.  
  396. /**
  397.  * Function that modifies the session description to remove the previous experimental H264
  398.  * codec that is apparently breaking connections.
  399.  * NOTE: We should perhaps not remove it since H264 is supported?
  400.  * @method _removeSDPFirefoxH264Pref
  401.  * @private
  402.  * @for Skylink
  403.  * @since 0.5.2
  404.  */
  405. Skylink.prototype._removeSDPFirefoxH264Pref = function(targetMid, sessionDescription) {
  406.   log.info([targetMid, 'RTCSessionDesription', sessionDescription.type,
  407.     'Removing Firefox experimental H264 flag to ensure interopability reliability']);
  408.  
  409.   return sessionDescription.sdp.replace(/a=fmtp:0 profile-level-id=0x42e00c;packetization-mode=1\r\n/g, '');
  410. };
  411.  
  412. /**
  413.  * Function that modifies the session description to remove apt/rtx lines that does exists.
  414.  * @method _removeSDPUnknownAptRtx
  415.  * @private
  416.  * @for Skylink
  417.  * @since 0.6.18
  418.  */
  419. Skylink.prototype._removeSDPUnknownAptRtx = function (targetMid, sessionDescription) {
  420.   var codecsPayload = []; // m=audio 9 UDP/TLS/RTP/SAVPF [Start from index 3] 102 9 0 8 97 13 118 101
  421.   var sdpLines = sessionDescription.sdp.split('\r\n');
  422.   var mediaLines = sessionDescription.sdp.split('m=');
  423.  
  424.   // Remove unmapped rtx lines
  425.   var formatRtx = function (str) {
  426.     (str.match(/a=rtpmap:.*\ rtx\/.*\r\n/gi) || []).forEach(function (line) {
  427.       var payload = (line.split('a=rtpmap:')[1] || '').split(' ')[0] || '';
  428.       var fmtpLine = (str.match(new RegExp('a=fmtp:' + payload + '\ .*\r\n', 'gi')) || [])[0];
  429.  
  430.       if (!fmtpLine) {
  431.         str = str.replace(new RegExp(line, 'g'), '');
  432.         return;
  433.       }
  434.  
  435.       var codecPayload = (fmtpLine.split(' apt=')[1] || '').replace(/\r\n/gi, '');
  436.       var rtmpLine = str.match(new RegExp('a=rtpmap:' + codecPayload + '\ .*\r\n', 'gi'));
  437.  
  438.       if (!rtmpLine) {
  439.         str = str.replace(new RegExp(line, 'g'), '');
  440.         str = str.replace(new RegExp(fmtpLine, 'g'), '');
  441.       }
  442.     });
  443.  
  444.     return str;
  445.   };
  446.  
  447.   // Remove unmapped fmtp and rtcp-fb lines
  448.   var formatFmtpRtcpFb = function (str) {
  449.     (str.match(/a=(fmtp|rtcp-fb):.*\ rtx\/.*\r\n/gi) || []).forEach(function (line) {
  450.       var payload = (line.split('a=' + (line.indexOf('rtcp') > 0 ? 'rtcp-fb' : 'fmtp'))[1] || '').split(' ')[0] || '';
  451.       var rtmpLine = str.match(new RegExp('a=rtpmap:' + payload + '\ .*\r\n', 'gi'));
  452.  
  453.       if (!rtmpLine) {
  454.         str = str.replace(new RegExp(line, 'g'), '');
  455.       }
  456.     });
  457.  
  458.     return str;
  459.   };
  460.  
  461.   // Remove rtx or apt= lines that prevent connections for browsers without VP8 or VP9 support
  462.   // See: https://bugs.chromium.org/p/webrtc/issues/detail?id=3962
  463.   for (var m = 0; m < mediaLines.length; m++) {
  464.     mediaLines[m] = formatRtx(mediaLines[m]);
  465.     mediaLines[m] = formatFmtpRtcpFb(mediaLines[m]);
  466.   }
  467.  
  468.   return mediaLines.join('m=');
  469. };
  470.  
  471. /**
  472.  * Function that modifies the session description to remove codecs.
  473.  * @method _removeSDPCodecs
  474.  * @private
  475.  * @for Skylink
  476.  * @since 0.6.16
  477.  */
  478. Skylink.prototype._removeSDPCodecs = function (targetMid, sessionDescription) {
  479.   var audioSettings = this.getPeerInfo().settings.audio;
  480.  
  481.   var parseFn = function (type, codec) {
  482.     var payloadList = sessionDescription.sdp.match(new RegExp('a=rtpmap:(\\d*)\\ ' + codec + '.*', 'gi'));
  483.  
  484.     if (!(Array.isArray(payloadList) && payloadList.length > 0)) {
  485.       log.warn([targetMid, 'RTCSessionDesription', sessionDescription.type,
  486.         'Not removing "' + codec + '" as it does not exists.']);
  487.       return;
  488.     }
  489.  
  490.     for (var i = 0; i < payloadList.length; i++) {
  491.       var payload = payloadList[i].split(' ')[0].split(':')[1];
  492.  
  493.       log.info([targetMid, 'RTCSessionDesription', sessionDescription.type,
  494.         'Removing "' + codec + '" payload ->'], payload);
  495.  
  496.       sessionDescription.sdp = sessionDescription.sdp.replace(
  497.         new RegExp('a=rtpmap:' + payload + '\\ .*\\r\\n', 'g'), '');
  498.       sessionDescription.sdp = sessionDescription.sdp.replace(
  499.         new RegExp('a=fmtp:' + payload + '\\ .*\\r\\n', 'g'), '');
  500.       sessionDescription.sdp = sessionDescription.sdp.replace(
  501.         new RegExp('a=rtpmap:\\d+ rtx\\/\\d+\\r\\na=fmtp:\\d+ apt=' + payload + '\\r\\n', 'g'), '');
  502.  
  503.       // Remove the m-line codec
  504.       var sdpLines = sessionDescription.sdp.split('\r\n');
  505.  
  506.       for (var j = 0; j < sdpLines.length; j++) {
  507.         if (sdpLines[j].indexOf('m=' + type) === 0) {
  508.           var parts = sdpLines[j].split(' ');
  509.  
  510.           if (parts.indexOf(payload) >= 3) {
  511.             parts.splice(parts.indexOf(payload), 1);
  512.           }
  513.  
  514.           sdpLines[j] = parts.join(' ');
  515.           break;
  516.         }
  517.       }
  518.  
  519.       sessionDescription.sdp = sdpLines.join('\r\n');
  520.     }
  521.   };
  522.  
  523.   if (this._initOptions.disableVideoFecCodecs) {
  524.     if (this._hasMCU) {
  525.       log.warn([targetMid, 'RTCSessionDesription', sessionDescription.type,
  526.         'Not removing "ulpfec" or "red" codecs as connected to MCU to prevent connectivity issues.']);
  527.     } else {
  528.       parseFn('video', 'red');
  529.       parseFn('video', 'ulpfec');
  530.     }
  531.   }
  532.  
  533.   if (this._initOptions.disableComfortNoiseCodec && audioSettings && typeof audioSettings === 'object' && audioSettings.stereo) {
  534.     parseFn('audio', 'CN');
  535.   }
  536.  
  537.   if (window.webrtcDetectedBrowser === 'edge' &&
  538.     (((this._peerInformations[targetMid] || {}).agent || {}).name || 'unknown').name !== 'edge') {
  539.     sessionDescription.sdp = sessionDescription.sdp.replace(/a=rtcp-fb:.*\ x-message\ .*\r\n/gi, '');
  540.   }
  541.  
  542.   return sessionDescription.sdp;
  543. };
  544.  
  545. /**
  546.  * Function that modifies the session description to remove REMB packets fb.
  547.  * @method _removeSDPREMBPackets
  548.  * @private
  549.  * @for Skylink
  550.  * @since 0.6.16
  551.  */
  552. Skylink.prototype._removeSDPREMBPackets = function (targetMid, sessionDescription) {
  553.   if (!this._initOptions.disableREMB) {
  554.     return sessionDescription.sdp;
  555.   }
  556.  
  557.   log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Removing REMB packets.']);
  558.   return sessionDescription.sdp.replace(/a=rtcp-fb:\d+ goog-remb\r\n/g, '');
  559. };
  560.  
  561. /**
  562.  * Function that retrieves the session description selected codec.
  563.  * @method _getSDPSelectedCodec
  564.  * @private
  565.  * @for Skylink
  566.  * @since 0.6.16
  567.  */
  568. Skylink.prototype._getSDPSelectedCodec = function (targetMid, sessionDescription, type, beSilentOnLogs) {
  569.   var codecInfo = {
  570.     name: null,
  571.     implementation: null,
  572.     clockRate: null,
  573.     channels: null,
  574.     payloadType: null,
  575.     params: null
  576.   };
  577.  
  578.   if (!(sessionDescription && sessionDescription.sdp)) {
  579.     return codecInfo;
  580.   }
  581.  
  582.   sessionDescription.sdp.split('m=').forEach(function (mediaItem, index) {
  583.     if (index === 0 || mediaItem.indexOf(type + ' ') !== 0) {
  584.       return;
  585.     }
  586.  
  587.     var codecs = (mediaItem.split('\r\n')[0] || '').split(' ');
  588.     // Remove audio[0] 65266[1] UDP/TLS/RTP/SAVPF[2]
  589.     codecs.splice(0, 3);
  590.  
  591.     for (var i = 0; i < codecs.length; i++) {
  592.       var match = mediaItem.match(new RegExp('a=rtpmap:' + codecs[i] + '.*\r\n', 'gi'));
  593.  
  594.       if (!match) {
  595.         continue;
  596.       }
  597.  
  598.       // Format: codec/clockRate/channels
  599.       var parts = ((match[0] || '').replace(/\r\n/g, '').split(' ')[1] || '').split('/');
  600.  
  601.       // Ignore rtcp codecs, dtmf or comfort noise
  602.       if (['red', 'ulpfec', 'telephone-event', 'cn', 'rtx'].indexOf(parts[0].toLowerCase()) > -1) {
  603.         continue;
  604.       }
  605.  
  606.       codecInfo.name = parts[0];
  607.       codecInfo.clockRate = parseInt(parts[1], 10) || 0;
  608.       codecInfo.channels = parseInt(parts[2] || '1', 10) || 1;
  609.       codecInfo.payloadType = parseInt(codecs[i], 10);
  610.       codecInfo.params = '';
  611.  
  612.       // Get the list of codec parameters
  613.       var params = mediaItem.match(new RegExp('a=fmtp:' + codecs[i] + '.*\r\n', 'gi')) || [];
  614.       params.forEach(function (paramItem) {
  615.         codecInfo.params += paramItem.replace(new RegExp('a=fmtp:' + codecs[i], 'gi'), '').replace(/\ /g, '').replace(/\r\n/g, '');
  616.       });
  617.       break;
  618.     }
  619.   });
  620.  
  621.   if (!beSilentOnLogs) {
  622.     log.debug([targetMid, 'RTCSessionDesription', sessionDescription.type,
  623.       'Parsing session description "' + type + '" codecs ->'], codecInfo);
  624.   }
  625.  
  626.   return codecInfo;
  627. };
  628.  
  629. /**
  630.  * Function that modifies the session description to remove non-relay ICE candidates.
  631.  * @method _removeSDPFilteredCandidates
  632.  * @private
  633.  * @for Skylink
  634.  * @since 0.6.16
  635.  */
  636. Skylink.prototype._removeSDPFilteredCandidates = function (targetMid, sessionDescription) {
  637.   // Handle Firefox MCU Peer ICE candidates
  638.   if (targetMid === 'MCU' && sessionDescription.type === this.HANDSHAKE_PROGRESS.ANSWER &&
  639.     window.webrtcDetectedBrowser === 'firefox') {
  640.     sessionDescription.sdp = sessionDescription.sdp.replace(/ generation 0/g, '');
  641.     sessionDescription.sdp = sessionDescription.sdp.replace(/ udp /g, ' UDP ');
  642.   }
  643.  
  644.   if (this._initOptions.forceTURN && this._hasMCU) {
  645.     log.warn([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Not filtering ICE candidates as ' +
  646.       'TURN connections are enforced as MCU is present (and act as a TURN itself) so filtering of ICE candidate ' +
  647.       'flags are not honoured']);
  648.     return sessionDescription.sdp;
  649.   }
  650.  
  651.   if (this._initOptions.filterCandidatesType.host) {
  652.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Removing "host" ICE candidates.']);
  653.     sessionDescription.sdp = sessionDescription.sdp.replace(/a=candidate:.*host.*\r\n/g, '');
  654.   }
  655.  
  656.   if (this._initOptions.filterCandidatesType.srflx) {
  657.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Removing "srflx" ICE candidates.']);
  658.     sessionDescription.sdp = sessionDescription.sdp.replace(/a=candidate:.*srflx.*\r\n/g, '');
  659.   }
  660.  
  661.   if (this._initOptions.filterCandidatesType.relay) {
  662.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Removing "relay" ICE candidates.']);
  663.     sessionDescription.sdp = sessionDescription.sdp.replace(/a=candidate:.*relay.*\r\n/g, '');
  664.   }
  665.  
  666.   // sessionDescription.sdp = sessionDescription.sdp.replace(/a=candidate:(?!.*relay.*).*\r\n/g, '');
  667.  
  668.   return sessionDescription.sdp;
  669. };
  670.  
  671. /**
  672.  * Function that retrieves the current list of support codecs.
  673.  * @method _getCodecsSupport
  674.  * @private
  675.  * @for Skylink
  676.  * @since 0.6.18
  677.  */
  678. Skylink.prototype._getCodecsSupport = function (callback) {
  679.   var self = this;
  680.  
  681.   if (self._currentCodecSupport) {
  682.     callback(null);
  683.     return;
  684.   }
  685.  
  686.   self._currentCodecSupport = { audio: {}, video: {} };
  687.  
  688.   // Safari 11 REQUIRES a stream first before connection works, hence let's spoof it for now
  689.   if (AdapterJS.webrtcDetectedType === 'AppleWebKit') {
  690.     self._currentCodecSupport.audio = {
  691.       opus: ['48000/2']
  692.     };
  693.     self._currentCodecSupport.video = {
  694.       h264: ['48000']
  695.     };
  696.     return callback(null);
  697.   }
  698.  
  699.   try {
  700.     if (window.webrtcDetectedBrowser === 'edge') {
  701.       var codecs = RTCRtpSender.getCapabilities().codecs;
  702.  
  703.       for (var i = 0; i < codecs.length; i++) {
  704.         if (['audio','video'].indexOf(codecs[i].kind) > -1 && codecs[i].name) {
  705.           var codec = codecs[i].name.toLowerCase();
  706.           self._currentCodecSupport[codecs[i].kind][codec] = codecs[i].clockRate +
  707.             (codecs[i].numChannels > 1 ? '/' + codecs[i].numChannels : '');
  708.         }
  709.       }
  710.       // Ignore .fecMechanisms for now
  711.       callback(null);
  712.  
  713.     } else {
  714.       var pc = new RTCPeerConnection(null);
  715.       var offerConstraints = AdapterJS.webrtcDetectedType !== 'plugin' ? {
  716.         offerToReceiveAudio: true,
  717.         offerToReceiveVideo: true
  718.       } : {
  719.         mandatory: {
  720.           OfferToReceiveVideo: true,
  721.           OfferToReceiveAudio: true
  722.         }
  723.       };
  724.  
  725.       // Prevent errors and proceed with create offer still...
  726.       try {
  727.         var channel = pc.createDataChannel('test');
  728.         self._binaryChunkType = channel.binaryType || self._binaryChunkType;
  729.         self._binaryChunkType = self._binaryChunkType.toLowerCase().indexOf('array') > -1 ?
  730.           self.DATA_TRANSFER_DATA_TYPE.ARRAY_BUFFER : self._binaryChunkType;
  731.         // Set the value according to the property
  732.         for (var prop in self.DATA_TRANSFER_DATA_TYPE) {
  733.           if (self.DATA_TRANSFER_DATA_TYPE.hasOwnProperty(prop) &&
  734.             self._binaryChunkType.toLowerCase() === self.DATA_TRANSFER_DATA_TYPE[prop].toLowerCase()) {
  735.             self._binaryChunkType = self.DATA_TRANSFER_DATA_TYPE[prop];
  736.             break;
  737.           }
  738.         }
  739.       } catch (e) {}
  740.  
  741.       pc.createOffer(function (offer) {
  742.         self._currentCodecSupport = self._getSDPCodecsSupport(null, offer);
  743.         callback(null);
  744.  
  745.       }, function (error) {
  746.         callback(error);
  747.       }, offerConstraints);
  748.     }
  749.   } catch (error) {
  750.     callback(error);
  751.   }
  752. };
  753.  
  754. /**
  755.  * Function that modifies the session description to handle the connection settings.
  756.  * This is experimental and never recommended to end-users.
  757.  * @method _handleSDPConnectionSettings
  758.  * @private
  759.  * @for Skylink
  760.  * @since 0.6.16
  761.  */
  762. Skylink.prototype._handleSDPConnectionSettings = function (targetMid, sessionDescription, direction) {
  763.   var self = this;
  764.  
  765.   if (!self._sdpSessions[targetMid]) {
  766.     return sessionDescription.sdp;
  767.   }
  768.  
  769.   var sessionDescriptionStr = sessionDescription.sdp;
  770.  
  771.   // Handle a=end-of-candidates signaling for non-trickle ICE before setting remote session description
  772.   if (direction === 'remote' && !self.getPeerInfo(targetMid).config.enableIceTrickle) {
  773.     sessionDescriptionStr = sessionDescriptionStr.replace(/a=end-of-candidates\r\n/g, '');
  774.   }
  775.  
  776.   var sdpLines = sessionDescriptionStr.split('\r\n');
  777.   var peerAgent = ((self._peerInformations[targetMid] || {}).agent || {}).name || '';
  778.   var peerVersion = ((self._peerInformations[targetMid] || {}).agent || {}).version || 0;
  779.   var mediaType = '';
  780.   var bundleLineIndex = -1;
  781.   var bundleLineMids = [];
  782.   var mLineIndex = -1;
  783.   var settings = clone(self._sdpSettings);
  784.  
  785.   if (targetMid === 'MCU') {
  786.     settings.connection.audio = true;
  787.     settings.connection.video = true;
  788.     settings.connection.data = true;
  789.   }
  790.  
  791.   // Patches for MCU sending empty video stream despite audio+video is not sending at all
  792.   // Apply as a=inactive when supported
  793.   if (self._hasMCU) {
  794.     var peerStreamSettings = clone(self.getPeerInfo(targetMid)).settings || {};
  795.     settings.direction.audio.receive = targetMid === 'MCU' ? true : !!peerStreamSettings.audio;
  796.     settings.direction.audio.send = targetMid === 'MCU' ? true : false;
  797.     settings.direction.video.receive = targetMid === 'MCU' ? true : !!peerStreamSettings.video;
  798.     settings.direction.video.send = targetMid === 'MCU' ? true : false;
  799.   }
  800.  
  801.   if (direction === 'remote') {
  802.     var offerCodecs = self._getSDPCommonSupports(targetMid, sessionDescription);
  803.  
  804.     if (!offerCodecs.audio) {
  805.       settings.connection.audio = false;
  806.     }
  807.  
  808.     if (!offerCodecs.video) {
  809.       settings.connection.video = false;
  810.     }
  811.   }
  812.  
  813.   // ANSWERER: Reject only the m= lines. Returned rejected m= lines as well.
  814.   // OFFERER: Remove m= lines
  815.  
  816.   self._sdpSessions[targetMid][direction].mLines = [];
  817.   self._sdpSessions[targetMid][direction].bundleLine = '';
  818.   self._sdpSessions[targetMid][direction].connection = {
  819.     audio: null,
  820.     video: null,
  821.     data: null
  822.   };
  823.  
  824.   for (var i = 0; i < sdpLines.length; i++) {
  825.     // Cache the a=group:BUNDLE line used for remote answer from Edge later
  826.     if (sdpLines[i].indexOf('a=group:BUNDLE') === 0) {
  827.       self._sdpSessions[targetMid][direction].bundleLine = sdpLines[i];
  828.       bundleLineIndex = i;
  829.  
  830.     // Check if there's a need to reject m= line
  831.     } else if (sdpLines[i].indexOf('m=') === 0) {
  832.       mediaType = (sdpLines[i].split('m=')[1] || '').split(' ')[0] || '';
  833.       mediaType = mediaType === 'application' ? 'data' : mediaType;
  834.       mLineIndex++;
  835.  
  836.       self._sdpSessions[targetMid][direction].mLines[mLineIndex] = sdpLines[i];
  837.  
  838.       // Check if there is missing unsupported video codecs support and reject it regardles of MCU Peer or not
  839.       if (!settings.connection[mediaType]) {
  840.         log.log([targetMid, 'RTCSessionDesription', sessionDescription.type,
  841.           'Removing rejected m=' + mediaType + ' line ->'], sdpLines[i]);
  842.  
  843.         // Check if answerer and we do not have the power to remove the m line if index is 0
  844.         // Set as a=inactive because we do not have that power to reject it somehow..
  845.         // first m= line cannot be rejected for BUNDLE
  846.         if (self._peerConnectionConfig.bundlePolicy === self.BUNDLE_POLICY.MAX_BUNDLE &&
  847.           bundleLineIndex > -1 && mLineIndex === 0 && (direction === 'remote' ?
  848.           sessionDescription.type === this.HANDSHAKE_PROGRESS.OFFER :
  849.           sessionDescription.type === this.HANDSHAKE_PROGRESS.ANSWER)) {
  850.           log.warn([targetMid, 'RTCSessionDesription', sessionDescription.type,
  851.             'Not removing rejected m=' + mediaType + ' line ->'], sdpLines[i]);
  852.           settings.connection[mediaType] = true;
  853.           if (['audio', 'video'].indexOf(mediaType) > -1) {
  854.             settings.direction[mediaType].send = false;
  855.             settings.direction[mediaType].receive = false;
  856.           }
  857.           continue;
  858.         }
  859.  
  860.         if (window.webrtcDetectedBrowser === 'edge') {
  861.           sdpLines.splice(i, 1);
  862.           i--;
  863.           continue;
  864.         } else if (direction === 'remote' || sessionDescription.type === this.HANDSHAKE_PROGRESS.ANSWER) {
  865.           var parts = sdpLines[i].split(' ');
  866.           parts[1] = 0;
  867.           sdpLines[i] = parts.join(' ');
  868.           continue;
  869.         }
  870.       }
  871.     }
  872.  
  873.     if (direction === 'remote' && sdpLines[i].indexOf('a=candidate:') === 0 &&
  874.       !self.getPeerInfo(targetMid).config.enableIceTrickle) {
  875.       if (sdpLines[i + 1] ? !(sdpLines[i + 1].indexOf('a=candidate:') === 0 ||
  876.         sdpLines[i + 1].indexOf('a=end-of-candidates') === 0) : true) {
  877.         log.info([targetMid, 'RTCSessionDesription', sessionDescription.type,
  878.           'Appending end-of-candidates signal for non-trickle ICE connection.']);
  879.         sdpLines.splice(i + 1, 0, 'a=end-of-candidates');
  880.         i++;
  881.       }
  882.     }
  883.  
  884.     if (mediaType) {
  885.       // Remove lines if we are rejecting the media and ensure unless (rejectVideoMedia is true), MCU has to enable those m= lines
  886.       if (!settings.connection[mediaType]) {
  887.         sdpLines.splice(i, 1);
  888.         i--;
  889.  
  890.       // Store the mids session description
  891.       } else if (sdpLines[i].indexOf('a=mid:') === 0) {
  892.         bundleLineMids.push(sdpLines[i].split('a=mid:')[1] || '');
  893.  
  894.       // Configure direction a=sendonly etc for local sessiondescription
  895.       }  else if (mediaType && ['a=sendrecv', 'a=sendonly', 'a=recvonly'].indexOf(sdpLines[i]) > -1) {
  896.         if (['audio', 'video'].indexOf(mediaType) === -1) {
  897.           self._sdpSessions[targetMid][direction].connection.data = sdpLines[i];
  898.           continue;
  899.         }
  900.  
  901.         if (direction === 'local') {
  902.           if (settings.direction[mediaType].send && !settings.direction[mediaType].receive) {
  903.             sdpLines[i] = sdpLines[i].indexOf('send') > -1 ? 'a=sendonly' : 'a=inactive';
  904.           } else if (!settings.direction[mediaType].send && settings.direction[mediaType].receive) {
  905.             sdpLines[i] = sdpLines[i].indexOf('recv') > -1 ? 'a=recvonly' : 'a=inactive';
  906.           } else if (!settings.direction[mediaType].send && !settings.direction[mediaType].receive) {
  907.           // MCU currently does not support a=inactive flag.. what do we do here?
  908.             sdpLines[i] = 'a=inactive';
  909.           }
  910.  
  911.           // Handle Chrome bundle bug. - See: https://bugs.chromium.org/p/webrtc/issues/detail?id=6280
  912.           if (!self._hasMCU && window.webrtcDetectedBrowser !== 'firefox' && peerAgent === 'firefox' &&
  913.             sessionDescription.type === self.HANDSHAKE_PROGRESS.OFFER && sdpLines[i] === 'a=recvonly') {
  914.             log.warn([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Overriding any original settings ' +
  915.               'to receive only to send and receive to resolve chrome BUNDLE errors.']);
  916.             sdpLines[i] = 'a=sendrecv';
  917.             settings.direction[mediaType].send = true;
  918.             settings.direction[mediaType].receive = true;
  919.           }
  920.         // Patch for incorrect responses
  921.         } else if (sessionDescription.type === self.HANDSHAKE_PROGRESS.ANSWER) {
  922.           var localOfferRes = self._sdpSessions[targetMid].local.connection[mediaType];
  923.           // Parse a=sendonly response
  924.           if (localOfferRes === 'a=sendonly') {
  925.             sdpLines[i] = ['a=inactive', 'a=recvonly'].indexOf(sdpLines[i]) === -1 ?
  926.               (sdpLines[i] === 'a=sendonly' ? 'a=inactive' : 'a=recvonly') : sdpLines[i];
  927.           // Parse a=recvonly
  928.           } else if (localOfferRes === 'a=recvonly') {
  929.             sdpLines[i] = ['a=inactive', 'a=sendonly'].indexOf(sdpLines[i]) === -1 ?
  930.               (sdpLines[i] === 'a=recvonly' ? 'a=inactive' : 'a=sendonly') : sdpLines[i];
  931.           // Parse a=sendrecv
  932.           } else if (localOfferRes === 'a=inactive') {
  933.             sdpLines[i] = 'a=inactive';
  934.           }
  935.         }
  936.         self._sdpSessions[targetMid][direction].connection[mediaType] = sdpLines[i];
  937.       }
  938.     }
  939.  
  940.     // Remove weird empty characters for Edge case.. :(
  941.     if (!(sdpLines[i] || '').replace(/\n|\r|\s|\ /gi, '')) {
  942.       sdpLines.splice(i, 1);
  943.       i--;
  944.     }
  945.   }
  946.  
  947.   // Fix chrome "offerToReceiveAudio" local offer not removing audio BUNDLE
  948.   if (bundleLineIndex > -1) {
  949.     if (self._peerConnectionConfig.bundlePolicy === self.BUNDLE_POLICY.MAX_BUNDLE) {
  950.       sdpLines[bundleLineIndex] = 'a=group:BUNDLE ' + bundleLineMids.join(' ');
  951.     // Remove a=group:BUNDLE line
  952.     } else if (self._peerConnectionConfig.bundlePolicy === self.BUNDLE_POLICY.NONE) {
  953.       sdpLines.splice(bundleLineIndex, 1);
  954.     }
  955.   }
  956.  
  957.   // Append empty space below
  958.   if (window.webrtcDetectedBrowser !== 'edge') {
  959.     if (!sdpLines[sdpLines.length - 1].replace(/\n|\r|\s/gi, '')) {
  960.       sdpLines[sdpLines.length - 1] = '';
  961.     } else {
  962.       sdpLines.push('');
  963.     }
  964.   }
  965.  
  966.   log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Handling connection lines and direction ->'], settings);
  967.  
  968.   return sdpLines.join('\r\n');
  969. };
  970.  
  971. /**
  972.  * Function that parses and retrieves the session description fingerprint.
  973.  * @method _getSDPFingerprint
  974.  * @private
  975.  * @for Skylink
  976.  * @since 0.6.18
  977.  */
  978. Skylink.prototype._getSDPFingerprint = function (targetMid, sessionDescription, beSilentOnLogs) {
  979.   var fingerprint = {
  980.     fingerprint: null,
  981.     fingerprintAlgorithm: null,
  982.     derBase64: null
  983.   };
  984.  
  985.   if (!(sessionDescription && sessionDescription.sdp)) {
  986.     return fingerprint;
  987.   }
  988.  
  989.   var sdpLines = sessionDescription.sdp.split('\r\n');
  990.  
  991.   for (var i = 0; i < sdpLines.length; i++) {
  992.     if (sdpLines[i].indexOf('a=fingerprint') === 0) {
  993.       var parts = sdpLines[i].replace('a=fingerprint:', '').split(' ');
  994.       fingerprint.fingerprint = parts[1];
  995.       fingerprint.fingerprintAlgorithm = parts[0];
  996.       break;
  997.     }
  998.   }
  999.  
  1000.   if (!beSilentOnLogs) {
  1001.     log.debug([targetMid, 'RTCSessionDesription', sessionDescription.type,
  1002.       'Parsing session description fingerprint ->'], fingerprint);
  1003.   }
  1004.  
  1005.   return fingerprint;
  1006. };
  1007.  
  1008. /**
  1009.  * Function that modifies the session description to append the MediaStream and MediaStreamTrack IDs that seems
  1010.  * to be missing from Firefox answer session description to Chrome connection causing freezes in re-negotiation.
  1011.  * @method _renderSDPOutput
  1012.  * @private
  1013.  * @for Skylink
  1014.  * @since 0.6.25
  1015.  */
  1016. Skylink.prototype._renderSDPOutput = function (targetMid, sessionDescription) {
  1017.   var self = this;
  1018.   var localStream = null;
  1019.   var localStreamId = null;
  1020.  
  1021.   if (!(sessionDescription && sessionDescription.sdp)) {
  1022.     return;
  1023.   }
  1024.  
  1025.   if (!self._peerConnections[targetMid]) {
  1026.     return sessionDescription.sdp;
  1027.   }
  1028.  
  1029.   if (self._peerConnections[targetMid].localStream) {
  1030.     localStream = self._peerConnections[targetMid].localStream;
  1031.     localStreamId = self._peerConnections[targetMid].localStreamId || self._peerConnections[targetMid].localStream.id;
  1032.   }
  1033.  
  1034.   // For non-trickle ICE, remove the a=end-of-candidates line first to append it properly later
  1035.   var sdpLines = (!self._initOptions.enableIceTrickle ? sessionDescription.sdp.replace(/a=end-of-candidates\r\n/g, '') : sessionDescription.sdp).split('\r\n');
  1036.   var agent = ((self._peerInformations[targetMid] || {}).agent || {}).name || '';
  1037.  
  1038.   // Parse and replace with the correct msid to prevent unwanted streams.
  1039.   // Making it simple without replacing with the track IDs or labels, neither setting prefixing "mslabel" and "label" as required labels.
  1040.   if (localStream) {
  1041.     var ssrcId = null;
  1042.     var mediaType = '';
  1043.  
  1044.     for (var i = 0; i < sdpLines.length; i++) {
  1045.       if (sdpLines[i].indexOf('m=') === 0) {
  1046.         mediaType = (sdpLines[i].split('m=')[1] || '').split(' ')[0] || '';
  1047.         mediaType = ['audio', 'video'].indexOf(mediaType) === -1 ? '' : mediaType;
  1048.  
  1049.       } else if (mediaType) {
  1050.         if (sdpLines[i].indexOf('a=msid:') === 0) {
  1051.           var msidParts = sdpLines[i].split(' ');
  1052.           msidParts[0] = 'a=msid:' + localStreamId;
  1053.           sdpLines[i] = msidParts.join(' ');
  1054.  
  1055.         } else if (sdpLines[i].indexOf('a=ssrc:') === 0) {
  1056.           var ssrcParts = null;
  1057.  
  1058.           // Replace for "msid:" and "mslabel:"
  1059.           if (sdpLines[i].indexOf(' msid:') > 0) {
  1060.             ssrcParts = sdpLines[i].split(' msid:');
  1061.           } else if (sdpLines[i].indexOf(' mslabel:') > 0) {
  1062.             ssrcParts = sdpLines[i].split(' mslabel:');
  1063.           }
  1064.  
  1065.           if (ssrcParts) {
  1066.             var ssrcMsidParts = (ssrcParts[1] || '').split(' ');
  1067.             ssrcMsidParts[0] = localStreamId;
  1068.             ssrcParts[1] = ssrcMsidParts.join(' ');
  1069.  
  1070.             if (sdpLines[i].indexOf(' msid:') > 0) {
  1071.               sdpLines[i] = ssrcParts.join(' msid:');
  1072.             } else if (sdpLines[i].indexOf(' mslabel:') > 0) {
  1073.               sdpLines[i] = ssrcParts.join(' mslabel:');
  1074.             }
  1075.           }
  1076.         }
  1077.       }
  1078.     }
  1079.   }
  1080.  
  1081.   // For non-trickle ICE, append the signaling of end-of-candidates properly
  1082.   if (!self._initOptions.enableIceTrickle){
  1083.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type,
  1084.       'Appending end-of-candidates signal for non-trickle ICE connection.']);
  1085.  
  1086.     for (var e = 0; e < sdpLines.length; e++) {
  1087.       if (sdpLines[e].indexOf('a=candidate:') === 0) {
  1088.         if (sdpLines[e + 1] ? !(sdpLines[e + 1].indexOf('a=candidate:') === 0 ||
  1089.           sdpLines[e + 1].indexOf('a=end-of-candidates') === 0) : true) {
  1090.           sdpLines.splice(e + 1, 0, 'a=end-of-candidates');
  1091.           e++;
  1092.         }
  1093.       }
  1094.     }
  1095.   }
  1096.  
  1097.   // Replace the bundle policy to prevent complete removal of m= lines for some cases that do not accept missing m= lines except edge.
  1098.   if (sessionDescription.type === this.HANDSHAKE_PROGRESS.ANSWER && this._sdpSessions[targetMid]) {
  1099.     var bundleLineIndex = -1;
  1100.     var mLineIndex = -1;
  1101.  
  1102.     for (var j = 0; j < sdpLines.length; j++) {
  1103.       if (sdpLines[j].indexOf('a=group:BUNDLE') === 0 && this._sdpSessions[targetMid].remote.bundleLine &&
  1104.         this._peerConnectionConfig.bundlePolicy === this.BUNDLE_POLICY.MAX_BUNDLE) {
  1105.         sdpLines[j] = this._sdpSessions[targetMid].remote.bundleLine;
  1106.       } else if (sdpLines[j].indexOf('m=') === 0) {
  1107.         mLineIndex++;
  1108.         var compareA = sdpLines[j].split(' ');
  1109.         var compareB = (this._sdpSessions[targetMid].remote.mLines[mLineIndex] || '').split(' ');
  1110.  
  1111.         if (compareA[0] && compareB[0] && compareA[0] !== compareB[0]) {
  1112.           compareB[1] = 0;
  1113.           log.info([targetMid, 'RTCSessionDesription', sessionDescription.type,
  1114.             'Appending middle rejected m= line ->'], compareB.join(' '));
  1115.           sdpLines.splice(j, 0, compareB.join(' '));
  1116.           j++;
  1117.           mLineIndex++;
  1118.         }
  1119.       }
  1120.     }
  1121.  
  1122.     while (this._sdpSessions[targetMid].remote.mLines[mLineIndex + 1]) {
  1123.       mLineIndex++;
  1124.       var appendIndex = sdpLines.length;
  1125.       if (!sdpLines[appendIndex - 1].replace(/\s/gi, '')) {
  1126.         appendIndex -= 1;
  1127.       }
  1128.       var parts = (this._sdpSessions[targetMid].remote.mLines[mLineIndex] || '').split(' ');
  1129.       parts[1] = 0;
  1130.       log.info([targetMid, 'RTCSessionDesription', sessionDescription.type,
  1131.         'Appending later rejected m= line ->'], parts.join(' '));
  1132.       sdpLines.splice(appendIndex, 0, parts.join(' '));
  1133.     }
  1134.   }
  1135.  
  1136.   // Ensure for chrome case to have empty "" at last line or it will return invalid SDP errors
  1137.   if (window.webrtcDetectedBrowser === 'edge' && sessionDescription.type === this.HANDSHAKE_PROGRESS.OFFER &&
  1138.     !sdpLines[sdpLines.length - 1].replace(/\s/gi, '')) {
  1139.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Removing last empty space for Edge browsers']);
  1140.     sdpLines.splice(sdpLines.length - 1, 1);
  1141.   }
  1142.  
  1143.   /*
  1144.   var outputStr = sdpLines.join('\r\n');
  1145.   if (window.webrtcDetectedBrowser === 'edge' && this._streams.userMedia && this._streams.userMedia.stream) {
  1146.     var correctStreamId = this._streams.userMedia.stream.id || this._streams.userMedia.stream.label;
  1147.     outputStr = outputStr.replace(new RegExp('a=msid:.*\ ', 'gi'), 'a=msid:' + correctStreamId + ' ');
  1148.     outputStr = outputStr.replace(new RegExp('\ msid:.*\ ', 'gi'), ' msid:' + correctStreamId + ' ');
  1149.   }*/
  1150.  
  1151.   log.info([targetMid, 'RTCSessionDescription', sessionDescription.type, 'Formatted output ->'], sdpLines.join('\r\n'));
  1152.  
  1153.   return sdpLines.join('\r\n');
  1154. };
  1155.  
  1156. /**
  1157.  * Function that parses the session description to get the MediaStream IDs.
  1158.  * NOTE: It might not completely accurate if the setRemoteDescription() fails..
  1159.  * @method _parseSDPMediaStreamIDs
  1160.  * @private
  1161.  * @for Skylink
  1162.  * @since 0.6.25
  1163.  */
  1164. Skylink.prototype._parseSDPMediaStreamIDs = function (targetMid, sessionDescription) {
  1165.   if (!this._peerConnections[targetMid]) {
  1166.     return;
  1167.   }
  1168.  
  1169.   if (!(sessionDescription && sessionDescription.sdp)) {
  1170.     this._peerConnections[targetMid].remoteStreamId = null;
  1171.     return;
  1172.   }
  1173.  
  1174.   var sdpLines = sessionDescription.sdp.split('\r\n');
  1175.   var currentStreamId = null;
  1176.  
  1177.   for (var i = 0; i < sdpLines.length; i++) {
  1178.     // a=msid:{31145dc5-b3e2-da4c-a341-315ef3ebac6b} {e0cac7dd-64a0-7447-b719-7d5bf042ca05}
  1179.     if (sdpLines[i].indexOf('a=msid:') === 0) {
  1180.       currentStreamId = (sdpLines[i].split('a=msid:')[1] || '').split(' ')[0];
  1181.       break;
  1182.     // a=ssrc:691169016 msid:c58721ed-b7db-4e7c-ac37-47432a7a2d6f 2e27a4b8-bc74-4118-b3d4-0f1c4ed4869b
  1183.     } else if (sdpLines[i].indexOf('a=ssrc:') === 0 && sdpLines[i].indexOf(' msid:') > 0) {
  1184.       currentStreamId = (sdpLines[i].split(' msid:')[1] || '').split(' ')[0];
  1185.       break;
  1186.     }
  1187.   }
  1188.  
  1189.   // No stream set
  1190.   if (!currentStreamId) {
  1191.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'No remote stream is sent.']);
  1192.     this._peerConnections[targetMid].remoteStreamId = null;
  1193.   // New stream set
  1194.   } else if (currentStreamId !== this._peerConnections[targetMid].remoteStreamId) {
  1195.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'New remote stream is sent ->'], currentStreamId);
  1196.     this._peerConnections[targetMid].remoteStreamId = currentStreamId;
  1197.   // Same stream set
  1198.   } else {
  1199.     log.info([targetMid, 'RTCSessionDesription', sessionDescription.type, 'Same remote stream is sent ->'], currentStreamId);
  1200.   }
  1201. };
  1202.  
  1203. /**
  1204.  * Function that parses and retrieves the session description ICE candidates.
  1205.  * @method _getSDPICECandidates
  1206.  * @private
  1207.  * @for Skylink
  1208.  * @since 0.6.18
  1209.  */
  1210. Skylink.prototype._getSDPICECandidates = function (targetMid, sessionDescription, beSilentOnLogs) {
  1211.   var candidates = {
  1212.     host: [],
  1213.     srflx: [],
  1214.     relay: []
  1215.   };
  1216.  
  1217.   if (!(sessionDescription && sessionDescription.sdp)) {
  1218.     return candidates;
  1219.   }
  1220.  
  1221.   sessionDescription.sdp.split('m=').forEach(function (mediaItem, index) {
  1222.     // Ignore the v=0 lines etc..
  1223.     if (index === 0) {
  1224.       return;
  1225.     }
  1226.  
  1227.     // Remove a=mid: and \r\n
  1228.     var sdpMid = ((mediaItem.match(/a=mid:.*\r\n/gi) || [])[0] || '').replace(/a=mid:/gi, '').replace(/\r\n/, '');
  1229.     var sdpMLineIndex = index - 1;
  1230.  
  1231.     (mediaItem.match(/a=candidate:.*\r\n/gi) || []).forEach(function (item) {
  1232.       // Remove \r\n for candidate type being set at the end of candidate DOM string.
  1233.       var canType = (item.split(' ')[7] || 'host').replace(/\r\n/g, '');
  1234.       candidates[canType] = candidates[canType] || [];
  1235.       candidates[canType].push(new RTCIceCandidate({
  1236.         sdpMid: sdpMid,
  1237.         sdpMLineIndex: sdpMLineIndex,
  1238.         // Remove initial "a=" in a=candidate
  1239.         candidate: (item.split('a=')[1] || '').replace(/\r\n/g, '')
  1240.       }));
  1241.     });
  1242.   });
  1243.  
  1244.   if (!beSilentOnLogs) {
  1245.     log.debug([targetMid, 'RTCSessionDesription', sessionDescription.type,
  1246.       'Parsing session description ICE candidates ->'], candidates);
  1247.   }
  1248.  
  1249.   return candidates;
  1250. };
  1251.  
  1252. /**
  1253.  * Function that gets each media line SSRCs.
  1254.  * @method _getSDPMediaSSRC
  1255.  * @private
  1256.  * @for Skylink
  1257.  * @since 0.6.18
  1258.  */
  1259. Skylink.prototype._getSDPMediaSSRC = function (targetMid, sessionDescription, beSilentOnLogs) {
  1260.   var ssrcs = {
  1261.     audio: 0,
  1262.     video: 0
  1263.   };
  1264.  
  1265.   if (!(sessionDescription && sessionDescription.sdp)) {
  1266.     return ssrcs;
  1267.   }
  1268.  
  1269.   sessionDescription.sdp.split('m=').forEach(function (mediaItem, index) {
  1270.     // Ignore the v=0 lines etc..
  1271.     if (index === 0) {
  1272.       return;
  1273.     }
  1274.  
  1275.     var mediaType = (mediaItem.split(' ')[0] || '');
  1276.     var ssrcLine = (mediaItem.match(/a=ssrc:.*\r\n/) || [])[0];
  1277.  
  1278.     if (typeof ssrcs[mediaType] !== 'number') {
  1279.       return;
  1280.     }
  1281.  
  1282.     if (ssrcLine) {
  1283.       ssrcs[mediaType] = parseInt((ssrcLine.split('a=ssrc:')[1] || '').split(' ')[0], 10) || 0;
  1284.     }
  1285.   });
  1286.  
  1287.   if (!beSilentOnLogs) {
  1288.     log.debug([targetMid, 'RTCSessionDesription', sessionDescription.type,
  1289.       'Parsing session description media SSRCs ->'], ssrcs);
  1290.   }
  1291.  
  1292.   return ssrcs;
  1293. };
  1294.  
  1295. /**
  1296.  * Function that parses the current list of supported codecs from session description.
  1297.  * @method _getSDPCodecsSupport
  1298.  * @private
  1299.  * @for Skylink
  1300.  * @since 0.6.18
  1301.  */
  1302. Skylink.prototype._getSDPCodecsSupport = function (targetMid, sessionDescription) {
  1303.   var self = this;
  1304.   var codecs = {
  1305.     audio: {},
  1306.     video: {}
  1307.   };
  1308.  
  1309.   if (!(sessionDescription && sessionDescription.sdp)) {
  1310.     return codecs;
  1311.   }
  1312.  
  1313.   var sdpLines = sessionDescription.sdp.split('\r\n');
  1314.   var mediaType = '';
  1315.  
  1316.   for (var i = 0; i < sdpLines.length; i++) {
  1317.     if (sdpLines[i].indexOf('m=') === 0) {
  1318.       mediaType = (sdpLines[i].split('m=')[1] || '').split(' ')[0];
  1319.       continue;
  1320.     }
  1321.  
  1322.     if (sdpLines[i].indexOf('a=rtpmap:') === 0) {
  1323.       var parts = (sdpLines[i].split(' ')[1] || '').split('/');
  1324.       var codec = (parts[0] || '').toLowerCase();
  1325.       var info = parts[1] + (parts[2] ? '/' + parts[2] : '');
  1326.  
  1327.       if (['ulpfec', 'red', 'telephone-event', 'cn', 'rtx'].indexOf(codec) > -1) {
  1328.         continue;
  1329.       }
  1330.  
  1331.       codecs[mediaType][codec] = codecs[mediaType][codec] || [];
  1332.  
  1333.       if (codecs[mediaType][codec].indexOf(info) === -1) {
  1334.         codecs[mediaType][codec].push(info);
  1335.       }
  1336.     }
  1337.   }
  1338.  
  1339.   log.info([targetMid || null, 'RTCSessionDescription', sessionDescription.type, 'Parsed codecs support ->'], codecs);
  1340.   return codecs;
  1341. };
  1342.  
  1343. /**
  1344.  * Function that checks if there are any common codecs supported for remote end.
  1345.  * @method _getSDPCommonSupports
  1346.  * @private
  1347.  * @for Skylink
  1348.  * @since 0.6.25
  1349.  */
  1350. Skylink.prototype._getSDPCommonSupports = function (targetMid, sessionDescription) {
  1351.   var self = this;
  1352.   var offer = {
  1353.     audio: false,
  1354.     video: false
  1355.   };
  1356.  
  1357.   if (!targetMid || !(sessionDescription && sessionDescription.sdp)) {
  1358.     offer.video = !!(self._currentCodecSupport.video.h264 || self._currentCodecSupport.video.vp8);
  1359.     offer.audio = !!self._currentCodecSupport.audio.opus;
  1360.  
  1361.     if (targetMid) {
  1362.       var peerAgent = ((self._peerInformations[targetMid] || {}).agent || {}).name || '';
  1363.  
  1364.       if (AdapterJS.webrtcDetectedBrowser === peerAgent) {
  1365.         offer.video = Object.keys(self._currentCodecSupport.video).length > 0;
  1366.         offer.audio = Object.keys(self._currentCodecSupport.audio).length > 0;
  1367.       }
  1368.     }
  1369.     return offer;
  1370.   }
  1371.  
  1372.   var remoteCodecs = self._getSDPCodecsSupport(targetMid, sessionDescription);
  1373.   var localCodecs = self._currentCodecSupport;
  1374.  
  1375.   for (var ac in localCodecs.audio) {
  1376.     if (localCodecs.audio.hasOwnProperty(ac) && localCodecs.audio[ac] && remoteCodecs.audio[ac]) {
  1377.       offer.audio = true;
  1378.       break;
  1379.     }
  1380.   }
  1381.  
  1382.   for (var vc in localCodecs.video) {
  1383.     if (localCodecs.video.hasOwnProperty(vc) && localCodecs.video[vc] && remoteCodecs.video[vc]) {
  1384.       offer.video = true;
  1385.       break;
  1386.     }
  1387.   }
  1388.  
  1389.   return offer;
  1390. };
  1391.  
  1392. /**
  1393.  * Function adds SCTP port number for Firefox 63.0.3 and above if its missing in the answer from MCU
  1394.  * @method _setSCTPport
  1395.  * @private
  1396.  * @for Skylink
  1397.  * @since 0.6.35
  1398.  */
  1399. Skylink.prototype._setSCTPport = function (targetMid, sessionDescription) {
  1400.   var self = this;
  1401.   if (AdapterJS.webrtcDetectedBrowser === 'firefox' && AdapterJS.webrtcDetectedVersion >= 63 && self._hasMCU === true) {
  1402.     var sdpLines = sessionDescription.sdp.split('\r\n');
  1403.     var mLineType = 'application';
  1404.     var mLineIndex = -1;
  1405.     var sdpType = sessionDescription.type;
  1406.  
  1407.     for (var i = 0; i < sdpLines.length; i++) {
  1408.       if (sdpLines[i].indexOf('m=' + mLineType) === 0) {
  1409.         mLineIndex = i;
  1410.       } else if (mLineIndex > 0) {
  1411.         if (sdpLines[i].indexOf('m=') === 0) {
  1412.           break;
  1413.         }
  1414.  
  1415.         // Saving m=application line when creating offer into instance variable
  1416.         if (sdpType === 'offer') {
  1417.           self._mline = sdpLines[mLineIndex];
  1418.           break;
  1419.         }
  1420.  
  1421.         // Replacing m=application line from instance variable
  1422.         if (sdpType === 'answer') {
  1423.           sdpLines[mLineIndex] = self._mline;
  1424.           sdpLines.splice(mLineIndex + 1, 0, 'a=sctp-port:5000');
  1425.           break;
  1426.         }
  1427.       }
  1428.     }
  1429.  
  1430.     return sdpLines.join('\r\n');
  1431.   }
  1432.  
  1433.   return sessionDescription.sdp;
  1434. };
  1435.  
  1436. /**
  1437.  * Function sets the original DTLS role which was negotiated on first offer/ansswer exchange
  1438.  * This needs to be done until https://bugzilla.mozilla.org/show_bug.cgi?id=1240897 is released in Firefox 68
  1439.  * Estimated release date for Firefox 68 : 2019-07-09 (https://wiki.mozilla.org/Release_Management/Calendar)
  1440.  * @method _setOriginalDTLSRole
  1441.  * @private
  1442.  * @for Skylink
  1443.  * @since 0.6.35
  1444.  */
  1445. Skylink.prototype._setOriginalDTLSRole = function (sessionDescription, isRemote) {
  1446.   var self = this;
  1447.   var sdpType = sessionDescription.type;
  1448.   var role = null;
  1449.   var aSetupPattern = null;
  1450.   var invertRoleMap = { active: 'passive', passive: 'active' };
  1451.  
  1452.   if (self._originalDTLSRole !== null || sdpType === 'offer') {
  1453.     return;
  1454.   }
  1455.  
  1456.   aSetupPattern = sessionDescription.sdp.match(/a=setup:([a-z]+)/);
  1457.  
  1458.   if (!aSetupPattern) {
  1459.     return;
  1460.   }
  1461.  
  1462.   role = aSetupPattern[1];
  1463.   self._originalDTLSRole = isRemote ? invertRoleMap[role] : role;
  1464. };
  1465.  
  1466.  
  1467. /**
  1468.  * Function that modifies the DTLS role in answer sdp
  1469.  * This needs to be done until https://bugzilla.mozilla.org/show_bug.cgi?id=1240897 is released in Firefox 68
  1470.  * Estimated release date for Firefox 68 : 2019-07-09 (https://wiki.mozilla.org/Release_Management/Calendar)
  1471.  * @method _modifyDTLSRole
  1472.  * @private
  1473.  * @for Skylink
  1474.  * @since 1.0.0
  1475.  */
  1476. Skylink.prototype._modifyDTLSRole = function (sessionDescription) {
  1477.   var self = this;
  1478.   var sdpType = sessionDescription.type;
  1479.  
  1480.   if (self._originalDTLSRole === null || sdpType === 'offer') {
  1481.     return;
  1482.   }
  1483.  
  1484.   sessionDescription.sdp = sessionDescription.sdp.replace(/a=setup:[a-z]+/g, 'a=setup:' + self._originalDTLSRole);
  1485.   return sessionDescription.sdp;
  1486. };
  1487.