ffmpeg nvenc command

[hanaluluelle]

what's the command for lossless encoding in nv12 pixel format using h264_nvenc?

i know i want my preset to be losslesshp(lossless high performance). what about profile? should it be main, high, or high444p?
should there be a command for the pixel format?

[poisondeathray]

what's the command for lossless encoding in nv12 pixel format using h264_nvenc?

i know i want my preset to be losslesshp(lossless high performance). what about profile? should it be main, high, or high444p?
should there be a command for the pixel format?

-pix_fmt nv12

The AVC profile will be set automatically

eg. (no audio)

ffmpeg -i input.ext -pix_fmt nv12 -c:v h264_nvenc -preset losslesshp -an output.mp4

[hanaluluelle]

doing this in obs gives the output a high444 profile. i wonder if that's just how it is with any lossless setup.

[poisondeathray]

doing this in obs gives the output a high444 profile. i wonder if that's just how it is with any lossless setup.

Yes, for AVC High444 is the only profile that supports lossless encoding
https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Profiles

But if you're recording something like a video game, it won't be "lossless". There will be no compression lossess, but there will be colorspace and chroma subsampling losses ( NV12 is chroma subsampled 4:2:0 )

NVEnc does support full unsubsampled color (4:4:4) in lossless mode, if you don't force NV12 . But it doesn't support RGB

[hanaluluelle]

will there be a noticeable performance impact using nvenc if i go from nv12 to 4:2:0? i've decided to just use cqp mode in obs. cqp 14 high quality preset and high profile seems indistinguishable.

[poisondeathray]

will there be a noticeable performance impact using nvenc if i go from nv12 to 4:2:0? i've decided to just use cqp mode in obs. cqp 14 high quality preset and high profile seems indistinguishable.

I don't understand your question

NV12 is 4:2:0

https://www.fourcc.org/pixel-format/yuv-nv12/

YV12, IYUV , I420, etc... are 4:2:0 too. They are just slightly different ways of arranging and storing the data. 4:2:0 just means the color information, the U,V planes have half width, half height . e.g. for 1920x1080 , the color information (each U, V plane) is only 960x540


But for NVEnc, and 4:2:0 encoding - it expects NV12 pixel format . If you send it something else, you willl get chroma errors. Rigaya's nvencc automatically converts to nv12 when encoding 4:2:0 if you send it something else

[hanaluluelle]

i meant changing the color format option in obs. it has both nv12 and i420.

[poisondeathray]

I don't know what obs is doing, maybe look at the log if there is one. If it's converting back and forth needlessly it would be slower. Or do some tests and time it if you really want to know. NVEnc, the actual encoder , expects NV12 .

[hanaluluelle]

i'll stick with nv12 since it's recommended by most including obs staff. i'm actually digging quicksync now, currently using la-icq with quality 12, async depth at 4, and lookahead depth at 40. i should tried this a long time ago. my intel gpu was just sitting there while i play