如何使用 MediaCodec trim 视频

Question

我正在尝试使用 MediaProjection API 录制屏幕。我想 trim 媒体投影录制的视频。有没有办法在不使用任何第三方依赖的情况下做到这一点？

Answer 1

经过大量挖掘，我找到了这个片段

  /**
 * @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)
private 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);
        }
    }
    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) {
                InstabugSDKLogger.d(TAG, "Saw input EOS.");
                bufferInfo.size = 0;
                break;
            } else {
                bufferInfo.presentationTimeUs = extractor.getSampleTime();
                if (endMs > 0 && bufferInfo.presentationTimeUs > (endMs * 1000)) {
                    InstabugSDKLogger.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.
        InstabugSDKLogger.w(TAG, "The source video file is malformed");
    } finally {
        muxer.release();
    }
    return;
}

编辑：只是为此命名来源。它来自 Google 的图库应用程序，它允许在名为 "VideoUtils" 的文件中显示 trim 个视频： https://android.googlesource.com/platform/packages/apps/Gallery2/+/634248d/src/com/android/gallery3d/app/VideoUtils.java

缺少的代码是：

private static final String LOGTAG = "VideoUtils";
private static final int DEFAULT_BUFFER_SIZE = 1 * 1024 * 1024;

Answer 2

我trim正在使用上面的代码。视频文件有 3 种轨道格式

{track-id=1, file-format=video/mp4, level=1024, mime=video/avc, frame-count=5427 , profile=8, language=, display-width=810, csd-1=java.nio.HeapByteBuffer[pos=0 lim=8 cap=8], durationUs=181080900, display-height=1440, 宽度=810, rotation-degrees=0, max-input-size=874801, frame-rate=30, height=1440, csd-0=java.nio.HeapByteBuffer[pos=0 lim=33 cap=33 ]}
{max-bitrate=125588, sample-rate=44100, track-id=2, file-format=video/mp4, mime=audio/mp4a-latm、配置文件=2、比特率=125588、语言=、aac-profile=2、durationUs=181138866、aac-format-adif=0、channel-count=2、max-input-size= 65538, csd-0=java.nio.HeapByteBuffer[pos=0 lim=2 cap=2]}
{text-format-data=java.nio.HeapByteBuffer[pos=0 lim=56 cap=56], track-id=3, file-format=video/mp4, durationUs=179640000, mime=text/3gpp-tt, 语言=, max-input-size=65536}

所以我可以 trim 那个视频。它抛出 MPEG4Writer：不支持 video/audio/metadata 以外的曲目 (text/3gpp-tt) MPEG4Writer：不支持的 MIME 'text/3gpp-tt'

但我只是trimming 视频文件。请任何人解决我的问题

如何使用 MediaCodec trim 视频

How to trim video with MediaCodec

android

mediamuxer

android-mediaprojection

android-mediacodec