title: AVCaptureVideoDataOutput videoSettings with kCVPixelBufferOpenGLESCompatibilityKey
body: <p>I am trying to get openGL compatible buffers from camera.
  I am setting up AVCaptureVideoDataOutput like this:</p>
  
  <pre><code>_videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
    [_videoDataOutput setSampleBufferDelegate:self queue:_sessionQueue];
    //  NSArray *pixelsFormats = _videoDataOutput.availableVideoCVPixelFormatTypes;
    [_videoDataOutput setVideoSettings:@{
      (NSString *)kCVPixelBufferPixelFormatTypeKey : @(kCVPixelFormatType_32BGRA),
      // Flag to enable emitting openGL frames from camera.
      (NSString *)kCVPixelBufferOpenGLESCompatibilityKey : @(YES)
    }];
    _videoDataOutput.alwaysDiscardsLateVideoFrames = YES;
  </code></pre>
  
  <p>But I get this error:</p>
  
  <pre><code>[AVCaptureVideoDataOutput setVideoSettings:] - videoSettings dictionary contains one or more unsupported (ignored) keys: (
      OpenGLESCompatibility
  )
  </code></pre>
  
  <p>Can I use kCVPixelBufferOpenGLESCompatibilityKey with AVCaptureVideoDataOutput?
  If not what is the best way to emit openGL compatible frames from camera?</p>
  
  <p>I have already considered creating CVOpenGLESTextureRef from CVImageBufferRef, but that needs a buffer copy from CPU to GPU. I am trying to avoid that.</p>
  
  <p>Note: I tried removing kCVPixelFormatType_32BGRA from settings. But still get same error.</p>