Open Radar

 
Summary:
In using AVCaptureConnection with AVVideoPreviewLayer, I've noticed something peculiar.  Connections associated with preview layers return NO from the supportsVideoFieldMode method, even though they are decidedly video-based connections.

I'm seeing this using code derived trivially from your sample code (AVRecorder), so I'm assuming that this is a bug in the implementation rather than a problem in the way I'm using the API.

Steps to Reproduce:
1.  Modify AVRecorderDocument.m in the AVRecorder sample code project as shown:

	[super windowControllerDidLoadNib:aController];
	
	// Attach preview to session
	CALayer *previewViewLayer = [[self previewView] layer];
	[previewViewLayer setBackgroundColor:CGColorGetConstantColor(kCGColorBlack)];
	AVCaptureVideoPreviewLayer *newPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:[self session]];
	[newPreviewLayer setFrame:[previewViewLayer bounds]];
	[newPreviewLayer setAutoresizingMask:kCALayerWidthSizable | kCALayerHeightSizable];
	[previewViewLayer addSublayer:newPreviewLayer];
	[self setPreviewLayer:newPreviewLayer];
	[newPreviewLayer release];
    
    AVCaptureConnection *connection = self.previewLayer.connection;
    
    if (connection.supportsVideoFieldMode) {
        NSLog(@"Enabled deinterlacing\n");
        [connection setVideoFieldMode:AVVideoFieldModeDeinterlace];
    } else {
        NSLog(@"Deinterlacing not supported\n");
    }
	
	// Start the session
	[[self session] startRunning];
	
	// Start updating the audio level meter
	[self setAudioLevelTimer:[NSTimer scheduledTimerWithTimeInterval:0.1f target:self selector:@selector(updateAudioLevels:) userInfo:nil repeats:YES]];


Expected Results:
I expected to find support for deinterlacing during preview.

Actual Results:
Instead, it returns "NO", and won't deinterlace the incoming video.

Version:
10.9.2/13C1021

Notes:


Configuration:


Attachments: