docs: int[] getChunkSizes(Track track) {
  
          long[] referenceChunkStarts = fragmenter.sampleNumbers(track);
          int[] chunkSizes = new int[referenceChunkStarts.length];
  
  
          for (int i = 0; i < referenceChunkStarts.length; i++) {
              long start = referenceChunkStarts[i] - 1;
              long end;
              if (referenceChunkStarts.length == i + 1) {
                  end = track.getSamples().size();
              } else {
                  end = referenceChunkStarts[i + 1] - 1;
              }
  
              chunkSizes[i] = l2i(end - start);
          }
          assert DefaultMp4Builder.this.track2Sample.get(track).size() == sum(chunkSizes) : "The number of samples and the sum of all chunk lengths must be equal";
          return chunkSizes;
  
  
      }