android - 如何在 Android MediaCodec 中设置演示文稿时间戳？

Question

我正在使用 MediaCodec(和 SurfaceView)在 Android 上渲染一个 h.264 视频。这是我的一些代码。

@Override
public void surfaceCreated(SurfaceHolder holder) {

}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    if (videoPlayer == null) {
        videoPlayer = new PlayerThread(holder.getSurface());
        videoPlayer.start();
    }
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    if (videoPlayer != null) {
        videoPlayer.interrupt();
        videoPlayer.isEOS = true;
        videoPlayer = null;
    }
}

private class PlayerThread extends Thread {
    private MediaCodec decoder;
    private Surface surface;
    private final static String mimeType = "video/avc";
    public boolean isEOS = false;

    public PlayerThread(Surface surface) {
        this.surface = surface;
    }

    @Override
    public void run() {
        MediaFormat format = MediaFormat.createVideoFormat(mimeType, frame.width, frame.height);
        decoder = MediaCodec.createDecoderByType(mimeType);
        decoder.configure(format, surface, null, 0);
        decoder.start();

        ByteBuffer[] inputBuffers = decoder.getInputBuffers();
        ByteBuffer[] outputBuffers = decoder.getOutputBuffers();

        int startPTS = 0;
        while (!Thread.interrupted() && !isEOS) {
            frame = frameReader.nextFrame();
            if (startPTS == 0) {
                startPTS = frame.pts;
            }
            int relativePTS = frame.pts - startPTS;
            int inIndex = decoder.dequeueInputBuffer(-1);
            if (inIndex >= 0)
            {
                ByteBuffer inputBuffer = inputBuffers[inIndex];
                inputBuffer.clear();
                inputBuffer.put(frame.buf, 0, frame.size);

                decoder.queueInputBuffer(inIndex, 0, frame.size, relativePTS*1000, 0);
            }

            MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();

            int outIndex = decoder.dequeueOutputBuffer(info, -1);

            switch (outIndex) {
                case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:
                    Log.d("DecodeActivity", "INFO_OUTPUT_BUFFERS_CHANGED");
                    outputBuffers = decoder.getOutputBuffers();
                    break;
                case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:
                    Log.d("DecodeActivity", "New format " + decoder.getOutputFormat());
                    break;
                case MediaCodec.INFO_TRY_AGAIN_LATER:
                    Log.d("DecodeActivity", "dequeueOutputBuffer timed out!");
                    break;
                default:
                    ByteBuffer outputBuffer = outputBuffers[outIndex];
                    Log.v("DecodeActivity", "We can't use this buffer but render it due to the API limit, " + outputBuffer);

                    decoder.releaseOutputBuffer(outIndex, true);
            }
        }

        /* clean */
        decoder.stop();
        decoder.release();
        decoder = null;
    }
}

我设置了 PTS，但它不起作用。视频播放速度非常快。

有人知道如何在这种情况下设置正确的呈现时间戳吗？任何帮助将不胜感激。

Answer 1

使用 MediaCodec 解码视频时，您不是设置 PTS 的人，您是接收 PTS 的人。当您调用设置了“渲染”标志的 releaseOutputBuffer() 时，您是在告诉系统尽快渲染帧。您有责任控制框架的节奏。

有关控制播放速率的基于 MediaCodec 的视频播放器的示例，请参阅 Grafika , 特别是 SpeedControlCallback 的使用类。