我正在编写一个Android应用程序，我有一堆5-15秒.mp4文件，我想剪辑。我一直在尝试使用Sebastian Annies'mp4parser来执行此操作，遵循此处给出的示例代码：ShortenExample。
这是我正在使用的代码（非常类似于上面的示例代码）：
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];
}
我似乎无法阻止错误“使用SyncSample的其他曲目已经更正了startTime。不支持。”从发生。当我记录循环播放的曲目时，getHandler（）返回“vide”，“soun”，然后在“提示”时崩溃。如果我评论这部分：
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.");
}
然后当程序到达行
时，程序崩溃时出现索引越界错误 Container out = new DefaultMp4Builder().build(movie);
我做错了什么？
答案 0 :(得分：3)
您收到IndexOutOfBoundsException，因为您的startSample或您的endSample在到达时有错误的值（例如仍为-1）
Container out = new DefaultMp4Builder().build(movie);
在我的示例中，使用start值进行小于2秒的剪切过程会导致if (currentTime > lastTime && currentTime <= start)永远不会达到真值，因此startSample未从中更新startSample初始值为-1。一种解决方案是将{{1}}的初始值从-1更改为0.
答案 1 :(得分：1)
使用此iso-parser库。https://code.google.com/p/mp4parser/downloads/detail?name=isoviewer-1.0-RC-28.jar&can=2&q=
private void doShorten(final int _startTime, final int _endTime) {
try {
File folder = new File(VideoPath);
Movie movie = MovieCreator.build(VideoPath);
List<Track> tracks = movie.getTracks();
movie.setTracks(new LinkedList<Track>());
// remove all tracks we will create new tracks from the old
double startTime = _startTime;
double endTime = _endTime;// (double) getDuration(tracks.get(0)) /
// tracks.get(0).getTrackMetaData().getTimescale();
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)
throw new RuntimeException(
"The startTime has already been corrected by another track with SyncSample. Not Supported.");
}
startTime = correctTimeToSyncSample(track, startTime, false);
endTime = correctTimeToSyncSample(track, endTime, true);
timeCorrected = true;
}
}
for (Track track : tracks) {
long currentSample = 0;
double currentTime = 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++) {
// entry.getDelta() is the amount of time the current
// sample covers.
if (currentTime <= startTime) {
// current sample is still before the new starttime
startSample = currentSample;
}
if (currentTime <= endTime) {
// current sample is after the new start time and
// still before the new endtime
endSample = currentSample;
} else {
// current sample is after the end of the cropped
// video
break;
}
currentTime += (double) entry.getDelta()
/ (double) track.getTrackMetaData()
.getTimescale();
currentSample++;
}
}
movie.addTrack(new CroppedTrack(track, startSample, endSample));
}
long start1 = System.currentTimeMillis();
Container out = new DefaultMp4Builder().build(movie);
long start2 = System.currentTimeMillis();
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(new Date());
String filename = "TrimVideo"+System.currentTimeMillis()+".mp4";
RandomAccessFile fc = new RandomAccessFile(
Environment.getExternalStorageDirectory()+"/myfolder/"+filename,
"rw");
FileChannel fc2 = fc.getChannel();
out.writeContainer(fc2);
fc2.close();
AddVideoInfo(filename);
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("TMP4_APP_OUT-%f-%f", startTime,
endTime)).length() / (start3 - start2) / 1000)
+ "MB/s");
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private void AddVideoInfo(String filename) {
// TODO Auto-generated method stub
File f = new File(Environment.getExternalStorageDirectory()
+ "/TotalRecall/"+filename);
EvientVideosListActivity.mVideoNamesList.add(f.getAbsolutePath());
Date lastModDate = new Date(f.lastModified());
SimpleDateFormat sdf = new SimpleDateFormat(
"MMM dd, yyyy hh:mm");
String date = sdf.format(lastModDate);
EvientVideosListActivity.mVideoDateList.add(date);
Bitmap bitmap = ThumbnailUtils.createVideoThumbnail(
f.getAbsolutePath(),
MediaStore.Video.Thumbnails.MINI_KIND);
EvientVideosListActivity.mVideoThumbsList.add(bitmap);
Global.mVideoCheckList.add(false);
}
long getDuration(Track track) {
long duration = 0;
for (TimeToSampleBox.Entry entry : track.getDecodingTimeEntries()) {
duration += entry.getCount() * entry.getDelta();
}
return duration;
}
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];
}