code: function getCodecPayloadType(sdpLine) {
              var pattern = new RegExp('a=rtpmap:(\\d+) \\w+\\/\\d+');
              var result = sdpLine.match(pattern);
              return (result && result.length === 2) ? result[1] : null;
          }
docs: Gets the codec payload type from an a=rtpmap:X line.