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POAVCaptureSession Display is White (no Video)
 

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    <p>I am using an AVCaptureSession with an output setting of:</p> <pre><code>NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey; NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange]; NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key]; [captureOutput setVideoSettings:videoSettings]; </code></pre> <p>My AVCaptureVideoPreviewLayer is displaying fine but I need more than this since I have had no success getting a screen shot using the AVCaptureVideoPreviewLayer. So when creating a CGContextRef within the captureOutput delegate, I am using these settings</p> <pre><code>uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer); size_t width = CVPixelBufferGetWidth(imageBuffer); size_t height = CVPixelBufferGetHeight(imageBuffer); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, width * 4, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); CGImageRef newImage = CGBitmapContextCreateImage(newContext); </code></pre> <p>I am no longer receiving an 'unsupported parameter combination' warning, but the display is just plain white. </p> <p>I should add that when I change</p> <pre><code>NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange]; </code></pre> <p>to</p> <pre><code>NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]; </code></pre> <p>Everything works fine. What is my problem?</p>
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    1. COFor one thing, you're trying to pull in YUV data from the camera. This comes in as two planes, Y and UV, and you're trying to create an RGB bitmap from this. That won't work, and is why telling the camera to give you BGRA input causes things to work fine.
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      1. USBrad Larson
    2. CORight, I figured as much. We have to use this video format (I think) because we are using the intensity information Y in an image processing application. So basically I am looking for the correct combination of settings to get access to each frame of video which I can display as a still image when appropriate. Even better would be some way to save and display a still frame of AVCaptureVideoPreviewLayer.
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    3. COTentatively suggests: AVCaptureStillImageOutput
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