docs: public long[] sampleNumbers(Track track) {
          long[] segmentStartSamples = new long[]{1};
          long[] sampleDurations = track.getSampleDurations();
          long[] syncSamples = track.getSyncSamples();
          long timescale = track.getTrackMetaData().getTimescale();
          double time = 0;
          for (int i = 0; i < sampleDurations.length; i++) {
              time += (double) sampleDurations[i] / timescale;
              if (time >= fragmentLength &&
                      (syncSamples == null || Arrays.binarySearch(syncSamples, i + 1) >= 0)) {
                  if (i > 0) {
                      segmentStartSamples = Mp4Arrays.copyOfAndAppend(segmentStartSamples, i + 1);
                  }
                  time = 0;
              }
          }
          return segmentStartSamples;
      }