Draw over SurfaceHolder/MediaPlayer on android?

Question

I'm working on a live wallpaper application. For the service, I'm playing a video as a wallpaper on loop using the MediaPlayer class. I would like to know if it's possible to draw over the video like it was a canvas, or at least a work around for do something like that (video playing and a drawn generated on top of it). I've been trying to make it work but no success at all after googling a lot and trying different alternatives.

The wallpaper service I'm using:

public class LiveWallpaperService extends WallpaperService {

@Override
public Engine onCreateEngine() {
    ThemeList.init(getApplicationContext());
    return new LiveWallpaperEngine();
}

private class LiveWallpaperEngine extends Engine {

    private MediaPlayer mp;
    private SurfaceHolder sh;
    private Uri L, P;

    public LiveWallpaperEngine() {
        checkConfig();
    }

    public void onSurfaceCreated(SurfaceHolder holder) {
        sh = new VideoHolder(holder);
    }

    @Override
    public void onSurfaceChanged(SurfaceHolder holder, int format,
            int width, int height) {
        super.onSurfaceChanged(holder, format, width, height);
    }

    @Override
    public void onVisibilityChanged(boolean visible) {
        //Check the current configuration
        checkConfig();
        if (visible) playTheme();
        /* 
        Canvas canvas = null;
        try {

            canvas = sh.lockCanvas();

            if (canvas != null) {
                Log.d("DRAW", "DRAWING!");
                Paint p = new Paint();
                p.setColor(Color.WHITE);
                p.setStrokeWidth(8.0f);
                p.setTextSize(100.0f);
                canvas.drawText("Testing", 150, 250, p);
            } else {
                Log.d("DRAW", "NOT DRAWING!");
            }
        } finally {
            sh.unlockCanvasAndPost(canvas);
        }*/
        super.onVisibilityChanged(visible);
    }

    private void playTheme() {
        //Check the current orientation and select the proper file to load
        mp = orientationCheck();
        //Start the video
        mp.setDisplay(sh);
        mp.setLooping(true);
        mp.start();
    }

    private MediaPlayer orientationCheck() {
        if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) {
            return MediaPlayer.create(getApplicationContext(), L);
        } else if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT) {
            return MediaPlayer.create(getApplicationContext(), P);
        } else {
            return MediaPlayer.create(getApplicationContext(), P);
        }
    }

    private void checkConfig() {
        //This code generates the L and P URIs based on the configuration set on the app
    }
}
}

The commented code is one of the things I tried to do it, but it gives java.lang.IllegalArgumentException: canvas object must be the same instance that was previously returned by lockCanvas"

The VideoHolder is just a class that extends from SurfaceHolder.

If I don't try to draw anything the video just plays fine, and the commented code works if the video is not initialized.

Thanks!