我正在开发一个使用 mp4parser 库(isoparser-1.0-RC-27.jar 和 aspectjrt-1.8.0.jar)合并 mp4 剪辑的应用程序。合并两个剪辑时,它们会变成一个剪辑,但随着向其中添加更多剪辑,输出的 mp4 会在视频后面显示音频。
代码如下:
Movie[] clips = new Movie[2];
//location of the movie clip storage
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "TestMerge");
//Build the two clips into movies
Movie firstClip = MovieCreator.build(first);
Movie secondClip = MovieCreator.build(second);
//Add both movie clips
clips[0] = firstClip;
clips[1] = secondClip;
//List for audio and video tracks
List<Track> videoTracks = new LinkedList<Track>();
List<Track> audioTracks = new LinkedList<Track>();
//Iterate all the movie clips and find the audio and videos
for (Movie movie: clips) {
for (Track track : movie.getTracks()) {
if (track.getHandler().equals("soun"))
audioTracks.add(track);
if (track.getHandler().equals("vide"))
videoTracks.add(track);
}
}
//Result movie from putting the audio and video together from the two clips
Movie result = new Movie();
//Append all audio and video
if (videoTracks.size() > 0)
result.addTrack(new AppendTrack(videoTracks.toArray(new Track[videoTracks.size()])));
if (audioTracks.size() > 0)
result.addTrack(new AppendTrack(audioTracks.toArray(new Track[audioTracks.size()])));
//Output the resulting movie to a new mp4 file
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String outputLocation = mediaStorageDir.getPath()+timeStamp;
Container out = new DefaultMp4Builder().build(result);
FileChannel fc = new RandomAccessFile(String.format(outputLocation), "rw").getChannel();
out.writeContainer(fc);
fc.close();
//Now set the active URL to play as the combined videos!
setURL(outputLocation);
}
我的猜测是,随着添加的剪辑越来越多,视频与音频的同步被打乱了,因为如果合并两个较长的剪辑,那么音频/视频就没问题了。无论如何,有没有办法防止多个较小剪辑中的视频和音频同步不佳,或者有没有人找到使用 mp4parser 这样做的解决方案? FFMpeg 是我正在考虑的另一种解决方案,但还没有发现其他人使用它来做到这一点
编辑: 我发现音频通常比视频长,因此,当添加越来越多的剪辑来创建一个剪辑时,这就是导致最终生成的视频偏移如此之多的原因。我将通过切断音频样本来解决
最佳答案
只是将代码添加到 Lucas 上面的回答中:
1.
LinkedList<Track> videoTracks = new LinkedList<>();
LinkedList<Track> audioTracks = new LinkedList<>();
double[] audioDuration = {0}, videoDuration = {0};
for (Movie m : clips) {
for (Track t : m.getTracks()) {
if (t.getHandler().equals("soun")) {
for (long a : t.getSampleDurations()) audioDuration[0] += ((double) a) / t.getTrackMetaData().getTimescale();
audioTracks.add(t);
} else if (t.getHandler().equals("vide")) {
for (long v : t.getSampleDurations()) videoDuration[0] += ((double) v) / t.getTrackMetaData().getTimescale();
videoTracks.add(t);
}
}
adjustDurations(videoTracks, audioTracks, videoDuration, audioDuration);
}
2.
private void adjustDurations(LinkedList<Track> videoTracks, LinkedList<Track> audioTracks, double[] videoDuration, double[] audioDuration) {
double diff = audioDuration[0] - videoDuration[0];
//nothing to do
if (diff == 0) {
return;
}
//audio is longer
LinkedList<Track> tracks = audioTracks;
//video is longer
if (diff < 0) {
tracks = videoTracks;
diff *= -1;
}
Track track = tracks.getLast();
long[] sampleDurations = track.getSampleDurations();
long counter = 0;
for (int i = sampleDurations.length - 1; i > -1; i--) {
if (((double) (sampleDurations[i]) / track.getTrackMetaData().getTimescale()) > diff) {
break;
}
diff -= ((double) (sampleDurations[i]) / track.getTrackMetaData().getTimescale());
audioDuration[0] -= ((double) (sampleDurations[i]) / track.getTrackMetaData().getTimescale());
counter++;
}
if (counter == 0) {
return;
}
track = new CroppedTrack(track, 0, track.getSamples().size() - counter);
//update the original reference
tracks.removeLast();
tracks.addLast(track);
}
关于java - 使用 mp4parser 合并 mp4 剪辑使音频隐藏在视频后面,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25857474/