[FFmpeg-user] Issue with hwaccel cuvid

[Dennis Mungai]

On Wed, 8 Apr 2020 at 19:04, Andy Sheimo <asheimo at gmail.com> wrote:

> This still produces the same error;
>
> ffmpeg -threads 1 -loglevel verbose -hwaccel cuvid
> -hwaccel_output_format cuda -c:v mpeg2_cuvid -extra_hw_frames 3 -i
> "l:\welter_originals\gamera the brave\Latatude Zero-trailer.mkv" -c:a copy
> -c:v h264_nvenc test.mkv
>
> But this works to complete the job;
>
> ffmpeg -threads 1 -loglevel verbose -hwaccel cuda
> -hwaccel_output_format cuda -extra_hw_frames 3 -i
> "l:\welter_originals\gamera the brave\Latatude Zero-trailer.mkv" -c:a copy
> -c:v h264_nvenc test.mkv
>
> By not specifying  -c:v mpeg2_cuvid do we know what decoder is being used?
> Is the process still completely in hardware? Do you think this is a
> limitation of the cuvid decoder?
>
> Thanks for your help. -Andy
>

NVDEC (an alias to the CUDA hwaccel) handles GPU memory quite differently
from CUVID, and when its' in use, the decoder is not specified.
CUVID, however, was never a true hwaccel, but rather a "wrapper" that
"brings up"/initializes a specific decoder by name passed to it via -c:v,
in a similar fashion to the bring-up seen with QuickSync (-hwaccel qsv).

I cannot speak much about why CUVID is failing on your end. I migrated all
my workflows to NVDEC an year ago.

Perhaps omitting the hwacccel_output_format with CUVID will help?

Try this:

ffmpeg -threads 1 -loglevel verbose -hwaccel cuvid
-c:v mpeg2_cuvid -extra_hw_frames 3 -i
"l:\welter_originals\gamera the brave\Latatude Zero-trailer.mkv" -c:a copy
-c:v h264_nvenc test.mkv

Then report back.