OSX+Radeon crash VideoDataBuffer.convert YCbCr_422 -> BGRA_PRE

[Kevin Rushforth]

I'm not surprised this causes problems, as it is almost certainly not 
thread-safe.

FWIW, this impl_ method is already inaccessible in JDK 9 because it 
returns a type that is not exported from the javafx.media module. 
Further, this methods will go away very soon as part of the ongoing 
encapsulation of all impl_ methods.

Can you file an RFE for a public API to do this? We can consider it for 
a future version of JavaFX.

-- Kevin


Chris Newland wrote:
> Hi,
>
> This is really just an FYI as I'm doing funky stuff with multiple
> MediaPlayers and using the deprecated impl_getLatestFrame() method to grab
> frames.
>
> I can grab frames fine with a single MediaPlayer instance but when I use
> multiple MediaPlayer objects each with an AnimationTimer calling this
> code:
>
> 	public void snapshotVideo()
> 	{
> 		VideoDataBuffer buf = player.impl_getLatestFrame();
>
> 		if (buf != null)
> 		{
> 			VideoFormat newFormat = VideoFormat.BGRA_PRE;
> 			buf = buf.convertToFormat(newFormat);
>
> 			ByteBuffer bb =
> buf.getBufferForPlane(VideoDataBuffer.PACKED_FORMAT_PLANE);
>
> 			int pixel = 0;
>
> 			int max = bb.remaining() / 4;
>
> 			for (int i = 0; i < max; i++)
> 			{
> 				rawFrameData[pixel++] = bb.getInt();
> 			}
>
> 			buf.releaseFrame();
> 		}
> 	}
>
> then it crashes hard on OSX El Capitan with AMD Radeon HD 6970M with this
> dump:
> https://gist.github.com/chriswhocodes/5516d24078205dc218dead870853e018
>
> I'm guessing the native frame conversion from YCbCr_422 to BGRA_PRE is not
> thread-safe but some naive attempts to lock around this haven't solved the
> problem.
>
> This same code + videos works fine on a MacBook Pro with Intel Iris
> graphics so it's a tiny hardware+OS corner case but thought it might be
> worth a mention.
>
> The only thing I'd add is that I'd love to have an official API for
> grabbing single frames from video. I've been doing some cool real-time
> video effects in JavaFX and it's a shame to have to use a deprecated
> method which will probably go away.
>
> Cheers,
>
> Chris
>
>