SDPUtils.parseRtpEncodingParameters = function()

in monitoring-stack-cdk/resources/frontend/connect-rtc.js [5141:5212]
62 lines of code
14 McCabe index (conditional complexity)

    SDPUtils.parseRtpEncodingParameters = function(mediaSection) {
      var encodingParameters = [];
      var description = SDPUtils.parseRtpParameters(mediaSection);
      var hasRed = description.fecMechanisms.indexOf('RED') !== -1;
      var hasUlpfec = description.fecMechanisms.indexOf('ULPFEC') !== -1;
    
      // filter a=ssrc:... cname:, ignore PlanB-msid
      var ssrcs = SDPUtils.matchPrefix(mediaSection, 'a=ssrc:')
        .map(function(line) {
          return SDPUtils.parseSsrcMedia(line);
        })
        .filter(function(parts) {
          return parts.attribute === 'cname';
        });
      var primarySsrc = ssrcs.length > 0 && ssrcs[0].ssrc;
      var secondarySsrc;
    
      var flows = SDPUtils.matchPrefix(mediaSection, 'a=ssrc-group:FID')
        .map(function(line) {
          var parts = line.substr(17).split(' ');
          return parts.map(function(part) {
            return parseInt(part, 10);
          });
        });
      if (flows.length > 0 && flows[0].length > 1 && flows[0][0] === primarySsrc) {
        secondarySsrc = flows[0][1];
      }
    
      description.codecs.forEach(function(codec) {
        if (codec.name.toUpperCase() === 'RTX' && codec.parameters.apt) {
          var encParam = {
            ssrc: primarySsrc,
            codecPayloadType: parseInt(codec.parameters.apt, 10)
          };
          if (primarySsrc && secondarySsrc) {
            encParam.rtx = {ssrc: secondarySsrc};
          }
          encodingParameters.push(encParam);
          if (hasRed) {
            encParam = JSON.parse(JSON.stringify(encParam));
            encParam.fec = {
              ssrc: primarySsrc,
              mechanism: hasUlpfec ? 'red+ulpfec' : 'red'
            };
            encodingParameters.push(encParam);
          }
        }
      });
      if (encodingParameters.length === 0 && primarySsrc) {
        encodingParameters.push({
          ssrc: primarySsrc
        });
      }
    
      // we support both b=AS and b=TIAS but interpret AS as TIAS.
      var bandwidth = SDPUtils.matchPrefix(mediaSection, 'b=');
      if (bandwidth.length) {
        if (bandwidth[0].indexOf('b=TIAS:') === 0) {
          bandwidth = parseInt(bandwidth[0].substr(7), 10);
        } else if (bandwidth[0].indexOf('b=AS:') === 0) {
          // use formula from JSEP to convert b=AS to TIAS value.
          bandwidth = parseInt(bandwidth[0].substr(5), 10) * 1000 * 0.95
              - (50 * 40 * 8);
        } else {
          bandwidth = undefined;
        }
        encodingParameters.forEach(function(params) {
          params.maxBitrate = bandwidth;
        });
      }
      return encodingParameters;
    };