私は Android アプリを作成しており、クリップしたい 5 ～ 15 秒の .mp4 ファイルがたくさんあります。ここに示すサンプルコードに従って、Sebastian Annies のmp4parserを使用しようとしています: ShortenExample。
これが私が使用しているコードです（上記のサンプルコードに非常に似ています）：
public static void clip(Sprinkle sprinkle, double start, double end) throws IOException {
Movie movie = MovieCreator.build(sprinkle.getLocalVideoPath());
// Save all tracks then remove them from movie
List<Track> tracks = movie.getTracks();
movie.setTracks(new LinkedList<Track>());
boolean timeCorrected = false;
// Here we try to find a track that has sync samples. Since we can only start decoding
// at such a sample we SHOULD make sure that the start of the new fragment is exactly
// such a frame
for (Track track : tracks) {
if (track.getSyncSamples() != null && track.getSyncSamples().length > 0) {
if (timeCorrected) {
// This exception here could be a false positive in case we have multiple tracks
// with sync samples at exactly the same positions. E.g. a single movie containing
// multiple qualities of the same video (Microsoft Smooth Streaming file)
Log.v("clip", "track.getSyncSamples().length: " + track.getSyncSamples().length);
throw new RuntimeException("The startTime has already been corrected by another track with SyncSample. Not Supported.");
}
Log.v("syncSample", "start before: " + start);
Log.v("syncSample", "end before: " + end);
start = correctTimeToSyncSample(track, start, false);
end = correctTimeToSyncSample(track, end, true);
Log.v("syncSample", "start after: " + start);
Log.v("syncSample", "end after: " + end);
timeCorrected = true;
}
}
for (Track track : tracks) {
long currentSample = 0;
double currentTime = 0;
double lastTime = 0;
long startSample = -1;
long endSample = -1;
for (int i = 0; i < track.getDecodingTimeEntries().size(); i++) {
TimeToSampleBox.Entry entry = track.getDecodingTimeEntries().get(i);
for (int j = 0; j < entry.getCount(); j++) {
if (currentTime > lastTime && currentTime <= start) {
// current sample is still before the new starttime
startSample = currentSample;
}
if (currentTime > lastTime && currentTime <= end) {
// current sample is after the new start time and still before the new endtime
endSample = currentSample;
}
lastTime = currentTime;
currentTime += (double) entry.getDelta() / (double) track.getTrackMetaData().getTimescale();
currentSample++;
}
}
movie.addTrack(new AppendTrack(new CroppedTrack(track, startSample, endSample)));
}
long start1 = System.currentTimeMillis();
Container out = new DefaultMp4Builder().build(movie);
long start2 = System.currentTimeMillis();
File file = Constants.getEditsDir();
FileOutputStream fos = new FileOutputStream(file.getPath() + String.format("output-%f-%f.mp4", start, end));
FileChannel fc = fos.getChannel();
out.writeContainer(fc);
fc.close();
fos.close();
long start3 = System.currentTimeMillis();
System.err.println("Building IsoFile took : " + (start2 - start1) + "ms");
System.err.println("Writing IsoFile took : " + (start3 - start2) + "ms");
System.err.println("Writing IsoFile speed : " + (new File(String.format("output-%f-%f.mp4", start, end)).length() / (start3 - start2) / 1000) + "MB/s");
}
private static double correctTimeToSyncSample(Track track, double cutHere, boolean next) {
double[] timeOfSyncSamples = new double[track.getSyncSamples().length];
long currentSample = 0;
double currentTime = 0;
for (int i = 0; i < track.getDecodingTimeEntries().size(); i++) {
TimeToSampleBox.Entry entry = track.getDecodingTimeEntries().get(i);
for (int j = 0; j < entry.getCount(); j++) {
if (Arrays.binarySearch(track.getSyncSamples(), currentSample + 1) >= 0) {
// samples always start with 1 but we start with zero therefore +1
timeOfSyncSamples[Arrays.binarySearch(track.getSyncSamples(), currentSample + 1)] = currentTime;
}
currentTime += (double) entry.getDelta() / (double) track.getTrackMetaData().getTimescale();
currentSample++;
}
}
double previous = 0;
for (double timeOfSyncSample : timeOfSyncSamples) {
if (timeOfSyncSample > cutHere) {
if (next) {
return timeOfSyncSample;
} else {
return previous;
}
}
previous = timeOfSyncSample;
}
return timeOfSyncSamples[timeOfSyncSamples.length - 1];
}
「StartTime は、SyncSample を使用する別のトラックによって既に修正されています。サポートされていません。」というエラーを防ぐことができないようです。発生から。ループしているトラックをログに記録すると、getHandler() は「ビデオ」、「サウンド」を返し、「ヒント」になるとクラッシュします。この部分をコメントアウトすると：
if (timeCorrected) {
// This exception here could be a false positive in case we have multiple tracks
// with sync samples at exactly the same positions. E.g. a single movie containing
// multiple qualities of the same video (Microsoft Smooth Streaming file)
Log.v("clip", "track.getSyncSamples().length: " + track.getSyncSamples().length);
throw new RuntimeException("The startTime has already been corrected by another track with SyncSample. Not Supported.");
}
その後、行に到達すると、プログラムはインデックス範囲外エラーでクラッシュします
Container out = new DefaultMp4Builder().build(movie);
私は何を間違っていますか？