Below code in gststreamsynchronizer seems wrong. gap event will get wrong start timestamp. The start time stamp should be segment start if segment rate bigger than 0 and should be segment stop if segment rate less then 0? Currently implement will cause audio sink get wrong gap event and block when rewind playback and demuxer send segment event (but not PCM data, demuxer output LPCM audio) and EOS event.

      if (seen_data && stream->segment.position != -1)
        timestamp = stream->segment.position;
      else if (stream->segment.rate < 0.0 || stream->segment.stop == -1)
        timestamp = stream->segment.start;
      else
        timestamp = stream->segment.stop;

Our implement will mute audio when rewind, so demuxer will send segment and eos event (without send any stream data) when rewind. If demuxer link with audio decoder, segment will be hold by decoder. stream synchronizer can't received the segment event. If demuxer output is LPCM audio, segment will sent to down streamer element. But current implement will use segment start time stamp as gap event start time stamp. It will cause audio sink get wrong gap event and block.