message: use GetMediaSSR instead of media.ssrc
diff: @@ -42,7 +42,7 @@ class IncomingStreamTrackMirrored
  //Internal function for adding a new mirrored encoding to the track
  const addEncoding = (encoding) => {
  //Create mirrored source
  - const source = new Native.RTPIncomingMediaStreamMultiplexer(encoding.source.media.ssrc, timeService);
  + const source = new Native.RTPIncomingMediaStreamMultiplexer(encoding.source.GetMediaSSRC(), timeService);
  //Get mirror encoding
  const mirrored = {
  