将H264帧解码为字节数组

Question

I have a stream of H264 video that I need to show in my Android app. If I consigure MediaCodec with a surface, then the video gets decoded to my app no problem, and I can see it in this surface.

But I also need to obtain a Bitmap of the video in certain moments (ie to store certain frames on the SD card). Is it possible to configure the MediaCodec library to return an array of bytes instead of working directly towards a surface??

Another option would be to obtain the bitmap directly from the surface, but I couldn't find this option on the SDK either.

Answer 1

You can use MediaMetadataRetriever :

MediaMetadataRetriever mediaMetadataRetriever=new MediaMetadataRetriever(); //should be stored as an instance variable
mediaMetadataRetriever.setDataSource(mVideo.getVideoUrl(Video.SD));
int time = videoView.getCurrentPosition()* 1000; //micro-to-milliseconds
Bitmap bmFrame = mediaMetadataRetriever.getFrameAtTime(time);

Edit:

To retrieve raw byte data without the involvement of UI, you can advance time frame by frame, get the Bitmap and convert it to byte array.

To be more efficient, consider forking FFmpegMediaMetadataRetriever , whose FFmpegMediaMetadataRetriever.java has method private native byte [] _getFrameAtTime(long timeUs, int option); skipping the whole Bitmap conversion process.

Answer 2

Try this:

public class GameView extends SurfaceView {
   private Bitmap bmp;
   private SurfaceHolder holder;

   public GameView(Context context) {
         super(context);
         holder = getHolder();
         holder.addCallback(new SurfaceHolder.Callback() {

                @Override
                public void surfaceDestroyed(SurfaceHolder holder) {
                }

                @Override
                public void surfaceCreated(SurfaceHolder holder) {
                       Canvas c = holder.lockCanvas(null);
                       onDraw(c);
                       holder.unlockCanvasAndPost(c);
                }

                @Override
                public void surfaceChanged(SurfaceHolder holder, int format,
                              int width, int height) {
                }
         });
         bmp = BitmapFactory.decodeResource(getResources(), R.drawable.icon);
   }

   @Override
   protected void onDraw(Canvas canvas) {
         canvas.drawColor(Color.BLACK);
         canvas.drawBitmap(bmp, 10, 10, null);
   }

}