TN3145: HDR video metadata

Question

OP

Apple

Created Mar ’23

Replies 2

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Learn about the usage and requirements of “Ambient Viewing Environment” metadata with Dolby Vision™ Profile 8.4 playback.

View Technote TN3145 >

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Answer 1

testinstadev OP

Apr ’23

How to attach ambientViewingEnvironment to new pixel buffer as attachment? I tried many things but it fails.

Update: It seems the attachment needs to be copied as NSData, example

 CVBufferSetAttachment(pixelBuffer, kCVImageBufferAmbientViewingEnvironmentKey, ambientViewingEnvironmentData! as NSData, .shouldPropagate)

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Answer 2

testinstadev OP

Oct ’23

@Jason It seems AVAssetWriter is crashing with error -12743 when appending NSData for kCVImageBufferAmbientViewingEnvironmentKey. Please describe how exactly to copy this attachment to new pixel buffer. Here is my code:

    var ambientViewingEnvironment:CMFormatDescription.Extensions.Value?
    var ambientViewingEnvironmentData:NSData?
     ambientViewingEnvironment = sampleBuffer.formatDescription?.extensions[.ambientViewingEnvironment]
     let plist = ambientViewingEnvironment?.propertyListRepresentation
       ambientViewingEnvironmentData = plist as? NSData

And then attaching this data,

   CVBufferSetAttachment(renderedPixelBuffer, kCVImageBufferAmbientViewingEnvironmentKey, ambientViewingEnvironmentData! as CFData, .shouldPropagate)

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