剪切视频工具类

public class ClipUtil {
    private static final String LOGTAG = "VideoUtils";
    private static final int DEFAULT_BUFFER_SIZE = 1 * 1024 * 1024;

    /**
     * @param srcPath  the path of source video file.
     * @param dstPath  the path of destination video file.
     * @param startMs  starting time in milliseconds for trimming. Set to
     *                 negative if starting from beginning.
     * @param endMs    end time for trimming in milliseconds. Set to negative if
     *                 no trimming at the end.
     * @param useAudio true if keep the audio track from the source.
     * @param useVideo true if keep the video track from the source.
     * @throws IOException
     */
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public static void genVideoUsingmuxer(String srcPath, String dstPath,
                                          int startMs, int endMs, boolean useAudio, boolean
                                                  useVideo)
            throws IOException {
        // Set up MediaExtractor to read from the source.
        MediaExtractor extractor = new MediaExtractor();
        extractor.setDataSource(srcPath);
        int trackCount = extractor.getTrackCount();
        // Set up Mediamuxer for the destination.
        MediaMuxer muxer;
        muxer = new MediaMuxer(dstPath,             
        MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
        // Set up the tracks and retrieve the max buffer size for selected
        // tracks.
        HashMap<Integer, Integer> indexMap = new HashMap<>(trackCount);
        int bufferSize = -1;
        for (int i = 0; i < trackCount; i++) {
            MediaFormat format = extractor.getTrackFormat(i);
            String mime = format.getString(MediaFormat.KEY_MIME);
            boolean selectCurrentTrack = false;
            if (mime.startsWith("audio/") && useAudio) {
                selectCurrentTrack = true;
            } else if (mime.startsWith("video/") && useVideo) {
                selectCurrentTrack = true;
            }
            if (selectCurrentTrack) {
                extractor.selectTrack(i);
                int dstIndex = muxer.addTrack(format);
                indexMap.put(i, dstIndex);
                if (format.containsKey(MediaFormat.KEY_MAX_INPUT_SIZE)) {
                    int newSize = format.getInteger(MediaFormat.KEY_MAX_INPUT_SIZE);
                    bufferSize = newSize > bufferSize ? newSize : bufferSize;
                }
            }
        }
        if (bufferSize < 0) {
            bufferSize = DEFAULT_BUFFER_SIZE;
        }
        // Set up the orientation and starting time for extractor.
        MediaMetadataRetriever retrieverSrc = new MediaMetadataRetriever();
        retrieverSrc.setDataSource(srcPath);
        String degreesString = retrieverSrc.extractMetadata(
                MediaMetadataRetriever.METADATA_KEY_VIDEO_ROTATION);
        if (degreesString != null) {
            int degrees = Integer.parseInt(degreesString);
            if (degrees >= 0) {
                muxer.setOrientationHint(degrees);
//                muxer.setorientationHint(degrees);
            }
        }
        if (startMs > 0) {
            extractor.seekTo(startMs * 1000, MediaExtractor.SEEK_TO_CLOSEST_SYNC);
        }
        // copy the samples from MediaExtractor to Mediamuxer. We will loop
        // for copying each sample and stop when we get to the end of the source
        // file or exceed the end time of the trimming.
        int offset = 0;
        int trackIndex = -1;
        ByteBuffer dstBuf = ByteBuffer.allocate(bufferSize);
        MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
        try {
            muxer.start();
            while (true) {
                bufferInfo.offset = offset;
                bufferInfo.size = extractor.readSampleData(dstBuf, offset);
                if (bufferInfo.size < 0) {
                    Log.d(TAG, "Saw input EOS.");
                    bufferInfo.size = 0;
                    break;
                } else {
                    bufferInfo.presentationTimeUs = extractor.getSampleTime();
                    if (endMs > 0 && bufferInfo.presentationTimeUs > (endMs * 1000)) {
                        Log.d(TAG, "The current sample is over the trim end time.");
                        break;
                    } else {
                        bufferInfo.flags = extractor.getSampleFlags();
                        trackIndex = extractor.getSampleTrackIndex();
                        muxer.writeSampleData(indexMap.get(trackIndex), dstBuf,
                                bufferInfo);
                        extractor.advance();
                    }
                }
            }
            muxer.stop();
            //deleting the old file
            File file = new File(srcPath);
//            file.delete();
        } catch (IllegalStateException e) {
            // Swallow the exception due to malformed source.
            Log.w(TAG, "The source video file is malformed");
        } finally {
            muxer.release();
        }
        return;
    }
}

取自googolgit 上一个谷歌工具类
https://android.googlesource.com/platform/packages/apps/Gallery2/+/634248d/src/com/android/gallery3d/app/VideoUtils.java