Investigate using FFmpeg's NVDEC hwaccels instead of the CUVID decoders

[ulmus-scott]

FFmpeg's maintainer for cuviddec.c recommends using the NVDEC hwaccels instead of the CUVID decoders.

From https://ffmpeg.org/pipermail/ffmpeg-devel/2025-February/340225.html

On 2/22/25 08:16, Timo Rothenpieler wrote:

On 22.02.2025 03:52, Scott Theisen wrote:

On 2/21/25 08:26, Timo Rothenpieler wrote:

I'd highly recommend to not use cuviddec anymore, but instead use
nvdec.
cuviddec only still exists to sanity-check nvdec against it at times.

.*_cuvid are FFCodecs while .*_nvdec are FFHWAccels. I don't know
what would be required to change to .*_nvdec and the .*_cuvid
FFCodecs work fine with this change.

You just use the normal native decoder and turn on hwaccel, to very
broadly summarize it.
Would also allow using a plethora of other hwaccels with the same
code. Pretty much how ffmpeg.c -hwaccel auto works.
If you already support things like vaapi/vdpau/d3d11va, you should
already have the code necessary to also use nvdec with minimal changes.