借助mp4Parser对视频进行裁剪

Question

我正在尝试修剪或剪切特定时间的视频，例如：- Video-1，它是30秒修剪到Video-2 10秒(0.10秒到0.20秒)。我能够做到这一点，并能够播放这个视频，但在视频的结尾，它给出错误的说法- Sorry! cant play this video.

public static void main(String args) throws IOException {

        Movie movie = new MovieCreator()
                .build(new RandomAccessFileIsoBufferWrapperImpl(
                        new File(
                                "/sdcard/Videos11/"+args+".mp4")));

        List<Track> tracks = movie.getTracks();
        movie.setTracks(new LinkedList<Track>());
        // remove all tracks we will create new tracks from the old

        double startTime = 3.000;
        double endTime = 9.000;

        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.");

            }
        }

        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));
        }

        IsoFile out = new DefaultMp4Builder().build(movie);

        String filePath = "sdcard/test"+i+".mp4";
        i++;
        File f = new File(filePath);
        FileOutputStream fos = new FileOutputStream(f);
        BufferedOutputStream bos = new BufferedOutputStream(fos, 65535);
        out.getBox(new IsoOutputStream(bos));
        bos.close();
        fos.close();

    }

附言：-我不太熟悉这个代码，但一些如何能够裁剪视频，但它在最后显示错误。

Answer 1

你应该“标准化”你的开始和停止值，使它们与mp4同步样本相对应，否则你会在输出视频甚至是损坏的文件上得到一些毛刺。

请看一下correctTimeToSyncSample方法：

1. Android Gallery source (使用mp4parser 0.9.x，I guess)
2. My sample project (使用mp4parser 1.1.18)。

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 = 0) {
            timeOfSyncSamples[Arrays.binarySearch(track.getSyncSamples(), currentSample + 1)] = currentTime;
        }
        currentTime += (double) delta / (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];
}

用法：

for (Track track : tracks) {
    if (track.getSyncSamples() != null && track.getSyncSamples().length > 0) {
        if (timeCorrected) {
            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;
    }
}

Answer 2

也许你想要剪切的位置在Iframe的中间。我也面临着类似的问题。我不能准确地剪切我想要的地方，因为在视频的开头我得到了糟糕的帧。你是不是在裁剪过的视频一开始就得到了坏帧？