MediaMetadataRetriever getFrameAtTime: videoframe is a null pointer

I´m trying to get a frame of a video, so I´m using MediaMetadataRetriever.getFrameAtTime() like this: ``` Uri directorio = Uri.parse("android.resource://com.extremeye/" + R.raw.video); media = new MediaMetadataRetriever(); media.setDataSource(this, directorio); frame = (ImageView)findViewById(R.id.frame); Bitmap bmFrame = media.getFrameAtTime(); frame.setImageBitmap(bmFrame); ``` But the problem is that I get: MediaMetadataRetriever getFrameAtTime: videoframe is a null pointer in the logCat. I´m sure that the video is compatible with android OS and the MediaMetadataRetriever loads it because I can get its metadata description without problems in a 2.3.3 OS version. I don´t know why I can´t get the frame but if I use a 4.2 OS version, it works perfectly. I tried to change the codec and the format of the video but it doesn´t work... I suppose that it´s a problem of format compatibility but I don´t know what I can do... Thanks!!