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List:       openjdk-openjfx-dev
Subject:    Re: OSX+Radeon crash VideoDataBuffer.convert YCbCr_422 -> BGRA_PRE
From:       "Chris Newland" <cnewland () chrisnewland ! com>
Date:       2016-05-25 14:22:54
Message-ID: 3f42a1dcade6ee4a67f96b84561f00a8.squirrel () excalibur ! xssl ! net
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Thanks Kevin, filed RFE with Review ID: JI-9038459.

I've found this was a really powerful way to do things like real-time
chroma keying (green screening) in JavaFX so will keep an OpenJFX snapshot
around to preserve this functionality.

Will be releasing another JavaFX tech demo soon :)

Cheers,

Chris

On Wed, May 25, 2016 13:29, Kevin Rushforth wrote:
> 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
>>
>>
>>
>


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