Can't append CMSampleBuffer to AVAssertWriterInput (error -12780) - ios

Question

I'm manually decoding h264 RTSP stream using ffmpeg and trying to save the uncompressed frames using AVAssertWriter and AVAssertWriterInput.
I'm getting the following error when calling AVAssetWriterInput appendBuffer -
Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo={NSUnderlyingError=0x170059530 {Error Domain=NSOSStatusErrorDomain Code=-12780 "(null)"}, NSLocalizedFailureReason=An unknown error occurred (-12780), NSLocalizedDescription=The operation could not be completed}
The CMSampleBuffer contains BGRA frames and looks like this -
CMSampleBuffer 0x159d12900 retainCount: 1 allocator: 0x1b3aa3bb8
invalid = NO
dataReady = YES
makeDataReadyCallback = 0x0
makeDataReadyRefcon = 0x0
formatDescription = <CMVideoFormatDescription 0x17405bd50 [0x1b3aa3bb8]> {
mediaType:'vide'
mediaSubType:'BGRA'
mediaSpecific: {
codecType: 'BGRA'
dimensions: 720 x 1280
}
extensions: {<CFBasicHash 0x1742652c0 [0x1b3aa3bb8]>{type = immutable dict, count = 4,
entries =>
0 : <CFString 0x1addb17c8 [0x1b3aa3bb8]>{contents = "CVImageBufferYCbCrMatrix"} = <CFString 0x1addb1808 [0x1b3aa3bb8]>{contents = "ITU_R_601_4"}
1 : <CFString 0x1addb1928 [0x1b3aa3bb8]>{contents = "CVImageBufferTransferFunction"} = <CFString 0x1addb17e8 [0x1b3aa3bb8]>{contents = "ITU_R_709_2"}
2 : <CFString 0x1adde3800 [0x1b3aa3bb8]>{contents = "CVBytesPerRow"} = <CFNumber 0xb00000000000b402 [0x1b3aa3bb8]>{value = +2880, type = kCFNumberSInt32Type}
3 : <CFString 0x1adde3880 [0x1b3aa3bb8]>{contents = "Version"} = <CFNumber 0xb000000000000022 [0x1b3aa3bb8]>{value = +2, type = kCFNumberSInt32Type}
}
}
}
sbufToTrackReadiness = 0x0
numSamples = 1
sampleTimingArray[1] = {
{PTS = {3000/90000 = 0.033}, DTS = {INVALID}, duration = {INVALID}},
}
imageBuffer = 0x17413ebe0
I've looked on the following question and answers as well but it doesn't seem to explain the issue I'm having (the format I used is a supported pixel format):
Why won't AVFoundation accept my planar pixel buffers on an iOS device?
Any help will be grateful!
FYI - When I save BGRA CMSampleBuffers I get from the iPhone camera it just works, if needed I can paste an example CMSampleBuffer as well.

Answer 1

I'll answer myself as I've found the issue -
The CMSampleBuffer wasn't IOSurface backed. I've used CVPixelBufferCreateWithBytes which created a CVPixelBuffer without IOSurface backing, as soon as I used CVPixelBufferCreate and passed the kCVPixelBufferIOSurfacePropertiesKey key it worked.
https://developer.apple.com/library/content/qa/qa1781/_index.html has all the information about creating IOSurface-backed CVPixelBuffers.