Do you convert the NAL start code to the MPEG format? Specifically, from the start code (0001) to a 4-byte NAL unit size? VideoToolbox specifically requires 4-byte size instead of start code

@galad87 VTRegisterSupplementalVideoDecoderIfAvailable() only available on macOS. But calling this func on my M1 Pro machine will add VP9 to supported list, but AV1 will be still unavailable