Technical Q&A QA1839

Specifying color space information for pixel buffers

Q:  Why does the AVAssetWriterInputPixelBufferAdaptor appendPixelBuffer:withPresentationTime: method fail with the AVAssetWriter error property set to -12917 (kVTInsufficientSourceColorDataErr) when I try to write pixel buffers not allocated from the provided CVPixelBufferPool to an output file?

A: The -12917 (kVTInsufficientSourceColorDataErr) error indicates a color space has not been specified for the source pixel buffers. If you are not using pixel buffers allocated from the provided CVPixelBufferPool for AVAssetWriterInputPixelBufferAdaptor instances you must specify color space information for the buffers.

For RGB source buffers, set the kCVImageBufferICCProfileKey or kCVImageBufferCGColorSpaceKey attachment on the buffer. Here’s an example of how to set a color space attachment for RGB pixel buffers on OS X:

Listing 1  Specifying a color space attachment for RGB pixel buffers on OS X.

CGColorSpaceRef sRGBColorSpace = CGColorSpaceCreateWithName(kCGColorSpaceSRGB);
if (sRGBColorSpace != NULL)
{
    CFDataRef sRGBProfileData = CGColorSpaceCopyICCProfile(sRGBColorSpace);
    if (sRGBProfileData != NULL)
    {
        NSDictionary *pbAttachements =
                    @{(id)kCVImageBufferICCProfileKey : (id)sRGBProfileData};
 
        CFRelease(sRGBProfileData);
 
        CVBufferRef pixelBuffer = <#Your pixel buffer#>;
 
        /* set the color space attachment on the buffer */
        CVBufferSetAttachments(pixelBuffer,
                    (CFDictionaryRef)pbAttachements, kCVAttachmentMode_ShouldPropagate);
    }
    else
    {
        NSLog(@"CGColorSpaceCopyICCProfile returned NULL");
 
        /* handle the error */
    }
 
    CFRelease(sRGBColorSpace);
}
else
{
    NSLog(@"CGColorSpaceCreateWithName returned NULL");
 
    /* handle the error */
}

Set the kCVImageBufferYCbCrMatrixKey, kCVImageBufferColorPrimariesKey, and kCVImageBufferTransferFunctionKey attachments to describe YUV buffers. Here's an example:

Listing 2  Specifying a color space attachment for YUV pixel buffers.

NSDictionary *pbAttachments =
    @{(id)kCVImageBufferYCbCrMatrixKey:(id)kCVImageBufferYCbCrMatrix_ITU_R_709_2,
     (id)kCVImageBufferColorPrimariesKey:(id)kCVImageBufferColorPrimaries_ITU_R_709_2,
     (id)kCVImageBufferTransferFunctionKey:(id)kCVImageBufferTransferFunction_ITU_R_709_2};
CVBufferRef pixelBuffer = <#Your pixel buffer#>;
CVBufferSetAttachments(pixelBuffer,
    (CFDictionaryRef)pbAttachments, kCVAttachmentMode_ShouldPropagate);

Document Revision History


DateNotes
2014-06-05

New document that describes how to specify color space information for pixel buffers




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