docs: protected Box createTfra(StreamingTrack track) {
          TrackFragmentRandomAccessBox tfra = new TrackFragmentRandomAccessBox();
          tfra.setVersion(1); // use long offsets and times
          long[] offsets = tfraOffsets.get(track);
          long[] times = tfraTimes.get(track);
          List<TrackFragmentRandomAccessBox.Entry> entries = new ArrayList<TrackFragmentRandomAccessBox.Entry>(times.length);
          for (int i = 0; i < times.length; i++) {
              entries.add(new TrackFragmentRandomAccessBox.Entry(times[i], offsets[i], 1, 1, 1));
          }
  
  
          tfra.setEntries(entries);
          tfra.setTrackId(track.getTrackExtension(TrackIdTrackExtension.class).getTrackId());
          return tfra;
      }