[FFmpeg-devel] [PATCH] lavc/nvenc: encode all RGB input as YUV444 rather than 420

[alatteri]

This looks useful.

http://ffmpeg.org/pipermail/ffmpeg-devel/2023-October/315276.html

[MartinPulec]

Well, IIRC when I've tried to add AV_PIX_FMT_X2RGB10 to the IS_YUV444() macro in FFmpeg, as it is in the patch, see comments here. I'll sum up:

1. without the patch, the x2rgb pixel format works correctly, but produces 10-bit YUV 4:2:0 only
2. with the patch, the colors were not correct

for this reason the pixel format is disabled - AV_PIX_FMT_GBRP16 is used for R10k and R12L input, which works correctly.

If you want to test after the patch gets upstream, you can try:

uv -t testcard:codec=R10k -c lavc:enc=hevc_nvenc --param lavc-use-codec=x2rgb10

lavc-use-codec enforces the use of the X2RGB pixfmt even though it is disabled otherwise. Anyways, as stated above, implicit GBRP16 works correctly producing RGB 4:4:4 10b stream now. Of course I'd be happy if we won't need to disable the pixfmt - it could have slight performance benefits (less RAW data) and there won't be exceptions in the code required.

I didn't test 8-bit RGB formats in the past, just now, and without the patch, point 1 holds (8b YUV 4:2:0 is encoded).