docs: protected boolean isChunkReady(StreamingTrack streamingTrack, StreamingSample next) {
          long ts = nextSampleStartTime.get(streamingTrack);
          long cfst = nextChunkCreateStartTime.get(streamingTrack);
  
          return (ts >= cfst + 2 * streamingTrack.getTimescale());
          // chunk interleave of 2 seconds
      }