lengthInSeconds = (double) isoFile.getMovieBox().getMovieHeaderBox().getDuration() / isoFile.getMovieBox().getMovieHeaderBox().getTimescale();

List<TrackBox> trackBoxes = isoFile.getMovieBox().getBoxes(TrackBox.class);

Iterator<TrackBox> iterator = trackBoxes.iterator();
 
SampleTableBox stbl = null;
TrackBox trackBox = null;
while (iterator.hasNext()) {
  trackBox = iterator.next();
  stbl = trackBox.getMediaBox().getMediaInformationBox().getSampleTableBox();
  // 我们只处理视频的关键帧，音频数据略过
  if (stbl.getSyncSampleBox() != null) {
    syncSamples = stbl.getSyncSampleBox().getSampleNumber();
    syncSamplesSize = new long[syncSamples.length];
    syncSamplesOffset = new long[syncSamples.length];
    timeOfSyncSamples = new double[syncSamples.length];
    break;
  }
}

// first we get all sample from the 'normal' MP4 part. if there are none - no problem.
SampleSizeBox sampleSizeBox = trackBox.getSampleTableBox().getSampleSizeBox();
ChunkOffsetBox chunkOffsetBox = trackBox.getSampleTableBox().getChunkOffsetBox();
SampleToChunkBox sampleToChunkBox = trackBox.getSampleTableBox().getSampleToChunkBox();

if (sampleToChunkBox != null
&& sampleToChunkBox.getEntries().size() > 0
&& chunkOffsetBox != null
&& chunkOffsetBox.getChunkOffsets().length > 0
&& sampleSizeBox != null && sampleSizeBox.getSampleCount() > 0) {
long[] numberOfSamplesInChunk = sampleToChunkBox.blowup(chunkOffsetBox.getChunkOffsets().length);
if (sampleSizeBox.getSampleSize() > 0) {
// Every sample has the same size! no need to store each size separately
// this happens when people use raw audio formats in MP4 (are you stupid guys???)
int sampleIndex = 0;
long sampleSize = sampleSizeBox.getSampleSize();
for (int i = 0; i < numberOfSamplesInChunk.length; i++) {
long thisChunksNumberOfSamples = numberOfSamplesInChunk[i];
long sampleOffset = chunkOffsetBox.getChunkOffsets()[i];
for (int j = 0; j < thisChunksNumberOfSamples; j++) {
   // samples always start with 1 but we start with zero
   // therefore +1
   int syncSamplesIndex = Arrays.binarySearch(syncSamples,sampleIndex + 1);
   if (syncSamplesIndex >= 0) {
      syncSamplesOffset[syncSamplesIndex] = sampleOffset;
      syncSamplesSize[syncSamplesIndex] = sampleSize;
   }
  sampleOffset += sampleSize;
  sampleIndex++;
}
}
} else {
// the normal case where all samples have different sizes
int sampleIndex = 0;
long sampleSizes[] = sampleSizeBox.getSampleSizes();
for (int i = 0; i < numberOfSamplesInChunk.length; i++) {
   long thisChunksNumberOfSamples = numberOfSamplesInChunk[i];
   long sampleOffset = chunkOffsetBox.getChunkOffsets()[i];
   for (int j = 0; j < thisChunksNumberOfSamples; j++) {
      long sampleSize = sampleSizes[sampleIndex];
      // samples always start with 1 but we start with zero therefore +1
      int syncSamplesIndex = Arrays.binarySearch(syncSamples, sampleIndex + 1);
      if (syncSamplesIndex >= 0) {
         syncSamplesOffset[syncSamplesIndex] = sampleOffset;
         syncSamplesSize[syncSamplesIndex] = sampleSize;
      }
      sampleOffset += sampleSize;
      sampleIndex++;
   }
}
}
 
MediaHeaderBox mdhd = trackBox.getMediaBox().getMediaHeaderBox();
TrackHeaderBox tkhd = trackBox.getTrackHeaderBox();
 
trackMetaData.setTrackId(tkhd.getTrackId());
trackMetaData.setCreationTime(DateHelper.convert(mdhd.getCreationTime()));
trackMetaData.setLanguage(mdhd.getLanguage());
trackMetaData.setModificationTime(DateHelper.convert(mdhd.getModificationTime()));
trackMetaData.setTimescale(mdhd.getTimescale());
trackMetaData.setHeight(tkhd.getHeight());
trackMetaData.setWidth(tkhd.getWidth());
trackMetaData.setLayer(tkhd.getLayer());
 
List<TimeToSampleBox.Entry> decodingTimeEntries = null;
if (trackBox.getParent().getBoxes(MovieExtendsBox.class).size() > 0) {
    decodingTimeEntries = new LinkedList<TimeToSampleBox.Entry>();
    for (MovieFragmentBox movieFragmentBox : trackBox.getIsoFile().getBoxes(MovieFragmentBox.class)) {
     List<TrackFragmentBox> trafs = movieFragmentBox.getBoxes(TrackFragmentBox.class);
       for (TrackFragmentBox traf : trafs) {
        if (traf.getTrackFragmentHeaderBox().getTrackId() == trackBox.getTrackHeaderBox().getTrackId()) {
          List<TrackRunBox> truns = traf.getBoxes(TrackRunBox.class);
          for (TrackRunBox trun : truns) {
             for (TrackRunBox.Entry entry : trun.getEntries()) {
               if (trun.isSampleDurationPresent()) {
                 if (decodingTimeEntries.size() == 0 || decodingTimeEntries.get(decodingTimeEntries.size() - 1).getDelta() != entry.getSampleDuration()) {
                    decodingTimeEntries.add(new TimeToSampleBox.Entry(1,entry.getSampleDuration()));
                 } else {
                    TimeToSampleBox.Entry e = decodingTimeEntries.get(decodingTimeEntries.size() - 1);
                    e.setCount(e.getCount() + 1);
               }
            }
         }
      }
    }
  }
}
} else {
    decodingTimeEntries = stbl.getTimeToSampleBox().getEntries();
}
 
long currentSample = 0;
double currentTime = 0;
for (TimeToSampleBox.Entry entry : decodingTimeEntries) {
   for (int j = 0; j < entry.getCount(); j++) {
      int syncSamplesIndex = Arrays.binarySearch(syncSamples,currentSample + 1);
      if (syncSamplesIndex >= 0) {
        // samples always start with 1 but we start with zero therefore +1
        timeOfSyncSamples[syncSamplesIndex] = currentTime;
   }
  currentTime += (double) entry.getDelta() / (double) trackMetaData.getTimescale();
  currentSample++;
 }
}
}

public void printinfo() {
System.out.println("视频总时长(秒): " + lengthInSeconds);
System.out.println("关键帧 \t 帧偏移 \t 帧大小 \t 帧对应的时间");
 
int size = syncSamples.length;
 
for (int i = 0; i < size; i++) {
   System.out.println(syncSamples[i] + " " + syncSamplesOffset[i] + " " + syncSamplesSize[i] + " " + timeOfSyncSamples[i]);
}
}