hi,
i'm exporting BGRA frames to h264 through AVAssetWriter on iOS.
no matter what information i tag the source CVPixelBuffer(s) with (709 CGColorSpace, 709 primaries, 709 transfer function, 709 conversion matrix), the resulting file seems to always be using 601 primaries.
if i tag the file as 601 and open it back up through AVFoundation the colors seem to match the source.
i've found this comment on the internet in some opensource software...
* AVAssetWriter will use BT.601 conversion matrix for RGB to YCbCr conversion
* regardless of the kCVImageBufferYCbCrMatrixKey value.
* Tagging the resulting video file as BT.601, is the best option right now.
* Creating a proper BT.709 video is not possible at the moment.
*/
my tests seem to confirm that this is the case.
can someone how knows more confirm this?
thanks