[FFmpeg-user] Clarification for decoding AV1 input on the GPU

[Mario Roy]

I also wanted to mention that -hwaccel nvdec -c:v av1 is noticeably slower
than -hwaccel nvdec -c:v av1_cuvid and not sure if this is the expected
performance.

AV1:
$ ffmpeg -y -hwaccel nvdec -c:v av1_cuvid -i input_av1.mp4 output.ts   #
GPU fps=653
$ ffmpeg -y -hwaccel nvdec -c:v av1 -i input_av1.mp4 output.ts         #
GPU fps=454
$ ffmpeg -y -hwaccel vdpau -c:v av1 -i input_av1.mp4 output.ts         #
GPU fps=246

VP9:
$ ffmpeg -y -hwaccel nvdec -c:v vp9_cuvid -i input_vp9.webm output.ts  #
GPU fps=669
$ ffmpeg -y -hwaccel nvdec -c:v vp9 -i input_vp9.webm output.ts        #
GPU fps=662
$ ffmpeg -y -hwaccel vdpau -c:v vp9 -i input_vp9.webm output.ts        #
GPU fps=529

Thanks,
Mario

On Wed, Jul 20, 2022 at 12:04 AM Mario Roy <marioeroy at gmail.com> wrote:

> Thank you, Haihao. I applied the patchset to FFmpeg 5.1 branch.  Passing
> -hwaccel {nvdec|vdpau} without -c:v av1 still decoded on the CPU. I double
> checked to be sure the patchset was applied.
>
> I obtained AV1 and VP9 samples via yt-dlp: 1920x1080 resolution.
>
> $ yt-dlp -F https://youtu.be/mIAfxj7nd9k
> $ yt-dlp -f 399 https://youtu.be/mIAfxj7nd9k -o input_av1.mp4
> $ yt-dlp -f 248 https://youtu.be/mIAfxj7nd9k -o input_vp9.webm
>
> Hardware: GeForce RTX 3070 FE
>
> AV1 Observations.
>
> $ ffmpeg -y -hwaccel nvdec -c:v av1_cuvid -i input_av1.mp4 output.ts   #
> GPU fps=653
> $ ffmpeg -y -hwaccel vdpau -c:v av1_cuvid -i input_av1.mp4 output.ts   #
> Core Dumps
> $ ffmpeg -y -hwaccel nvdec -c:v av1 -i input_av1.mp4 output.ts         #
> GPU fps=454
> $ ffmpeg -y -hwaccel vdpau -c:v av1 -i input_av1.mp4 output.ts         #
> GPU fps=246
> $ ffmpeg -y -hwaccel nvdec -i input_av1.mp4 output.ts                  #
> CPU libdav1d
> $ ffmpeg -y -hwaccel vdpau -i input_av1.mp4 output.ts                  #
> CPU libdav1d
>
> VP9 Observations.
>
> $ ffmpeg -y -hwaccel nvdec -c:v vp9_cuvid -i input_vp9.webm output.ts  #
> GPU fps=669
> $ ffmpeg -y -hwaccel vdpau -c:v vp9_cuvid -i input_vp9.webm output.ts  #
> Core Dumps
> $ ffmpeg -y -hwaccel nvdec -c:v vp9 -i input_vp9.webm output.ts        #
> GPU fps=662
> $ ffmpeg -y -hwaccel vdpau -c:v vp9 -i input_vp9.webm output.ts        #
> GPU fps=529
> $ ffmpeg -y -hwaccel nvdec -i input_vp9.webm output.ts                 #
> GPU fps=655
> $ ffmpeg -y -hwaccel vdpau -i input_vp9.webm output.ts                 #
> GPU fps=533
>
> Looking at the AV1 results, -hwaccel vdpau -c:v av1 is nearly 2x slower
> than -hwaccel nvdec -c:v av1.
>
> Should FFmpeg exit gracefully if passing unsupported options for -hwaccel
> vdpau? Or is this a bug?
> -hwaccel vdpau -c:v av1_cuvid  # Crashes
> -hwaccel vdpau -c:v vp9_cuvid  # Crashes
>
> Thanks,
> Mario
>
> On Tue, Jul 19, 2022 at 8:42 PM Xiang, Haihao <
> haihao.xiang-at-intel.com at ffmpeg.org> wrote:
>
>> On Tue, 2022-07-19 at 16:54 -0500, Mario Roy wrote:
>> > Greetings,
>> >
>> > With the recent FFmpeg 5.1 supporting AV1 using VDPAU, should decoding
>> AV1
>> > occur on the GPU automatically (NVIDIA 3000 series), similarly to
>> decoding
>> > VP9?
>> >
>> > ffmpeg -y -hwaccel vdpau -i input_av1.mp4 output.ts   # decodes on the
>> CPU
>>
>>
>> libdav1d has higher priority than the the native av1 decoder in FFmpeg,
>> you
>> should specify the native av1 in your command line if you want to use
>> vdpau.
>>
>> $ ffmpeg -y -hwaccel vdpau -c:v av1 -i input_av1.mp4 output.ts
>>
>> Or you may try
>>
>> https://patchwork.ffmpeg.org/project/ffmpeg/patch/20210922074207.19451-2-haihao.xiang@intel.com/
>>  which can decode AV1 on the GPU automatically when -hwaccel xxx is
>> specified in
>> the command line. (You need to rebase the patchset).
>>
>> Thanks
>> Haihao
>>
>>
>> > ffmpeg -y -hwaccel vdpau -i input_vp9.webm output.ts  # decodes on the
>> GPU
>> >
>> >  Are the following incorrect usage? Both segfaults.
>> >
>> > ffmpeg -y -hwaccel vdpau -c:v av1_cuvid -i input_av1.mp4 output.ts   #
>> > segfaults
>> > ffmpeg -y -hwaccel vdpau -c:v vp9_cuvid -i input_vp9.webm output.ts  #
>> > segfaults
>> >
>> > Thanks,
>> > Mario
>> >
>> > On Wed, Jul 13, 2022 at 9:44 AM Mario Roy <marioeroy at gmail.com> wrote:
>> >
>> > > Hi,
>> > >
>> > > What are the recommended arguments for folks using NVIDIA 3000 series
>> > > graphics and decoding AV1 media? I tried the same with VP9 media.
>> > >
>> > > The following was done using FFmpeg 5.1.
>> > >
>> > > ffmpeg -y -hwaccel vdpau -c:v av1_cuvid -i input_av1.mp4
>> > > output.ts   segfaults
>> > > ffmpeg -y -hwaccel vdpau -c:v vp9_cuvid -i input_vp9.webm
>> > > output.ts  segfaults
>> > >
>> > > ffmpeg -y -hwaccel vdpau -i input_av1.mp4 output.ts   decodes on the
>> CPU
>> > > ffmpeg -y -hwaccel vdpau -i input_vp9.webm output.ts  decodes on the
>> GPU
>> > >
>> > > ffmpeg -y -hwaccel nvdec -c:v av1_cuvid -i input_av1.mp4 output.ts
>> > > ffmpeg -y -hwaccel nvdec -c:v vp9_cuvid -i input_vp9.webm output.ts
>> > >
>> > > ffmpeg -y -c:v av1_cuvid -i input_av1.mp4 output.ts
>> > > ffmpeg -y -c:v vp9_cuvid -i input_vp9.webm output.ts
>> > >
>> > > Best,
>> > > Mario
>> > >
>> > >
>> >
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