5

我正在编写一个 Android 应用程序,我有一堆 5-15 秒的 .mp4 文件要剪辑。我一直在尝试使用 Sebastian Annies 的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“开始时间已被另一个使用 SyncSample 的轨道更正。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“hint”时崩溃。如果我将此部分注释掉:

    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.");
        }

然后程序在到达该行时会因索引越界错误而崩溃

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

我究竟做错了什么?

4

2 回答 2

3

您收到 IndexOutOfBoundsException,因为您startSample或您endSample在到达时的值有误(例如仍为 -1)

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

在我的示例中,使用start小于 2 秒的剪辑过程值会导致效果if (currentTime > lastTime && currentTime <= start)从未达到真实值,因此startSample不会从其初始值 -1 更新。一种解决方案是将初始值startSample从 -1 更改为 0。

于 2013-12-09T10:35:05.713 回答
1

使用这个 iso 解析器库。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];
}
于 2014-11-10T11:44:49.387 回答