[FFmpeg-user] overlay_qsv with hardware decode and encode

[Greg Oliver]

On Thu, Feb 27, 2025 at 11:49 PM Vladimir Mishonov via ffmpeg-user <
ffmpeg-user at ffmpeg.org> wrote:

> On 2025-02-28 02:36, Greg Oliver wrote:
>
> > On Thu, Feb 27, 2025 at 11:25 AM Vladimir Mishonov via ffmpeg-user <
> > ffmpeg-user at ffmpeg.org> wrote:
> >
> >
> > https://ffmpeg.org/pipermail/ffmpeg-user/2024-August/058638.html
> >
>
> Thanks for the link. Unfortunately, that seems to be only tangentially
> related to my scenario because:
>
> 1) The resolutions of each input stream do not change over time.
>
> 2) I can use software decoding and I do not need to insert any scale
> filters before sending the streams to hardware:
>
> ffmpeg -init_hw_device vaapi=hw -filter_hw_device hw \
>  -i rtmp://localhost/stream1 \
>  -i rtmp://localhost/stream2 \
>  -filter_complex
> "[0:v]format=nv12,hwupload=extra_hw_frames=120[i0];[1:v]format=nv12,hwupload=extra_hw_frames=120[i1];[i0][i1]overlay_vaapi=w=500"
>
> \
>  -c:v h264_vaapi -global_quality 25 -g 50 -r 25 -an -f null -
>
> The above command works regardless of whether the input resolutions are
> the same, or different. The CPU usage is quite low, but still
> noticeable. Note that even if some kind of filter does get automatically
> inserted, it does not interfere with the videos themselves in any way -
> otherwise, I would have noticed it long ago either because of excessive
> CPU usage, or the resolution and/or the content of the output stream
> being different from what is expected, or both.
>
> It would also be, in principle, fundamentally wrong to apply any kind of
> software processing in a (theoretically) purely hardware filter pipeline
> - not to mention pointless due to the overlay filter in the end, which
> performs its own scaling anyway.
>
> P.S. sorry for top-posting the previous response, I forget it's not
> customary because I very rarely use mailing lists, only when there is no
> other option.
>

Sorry - that link I referenced actually did not have the whole thread.  The
piece I intended to be included was:

https://lists.ffmpeg.org/pipermail/ffmpeg-user/2024-September/058652.html

If that does not solve it - sorry - I do not use QSV (except in Plex) for
anything - I just remembered seeing that email thread a while back, so
looked it up.  This one has a resolution, but I am unsure if it is software
or hardware.



> ---
> Kind regards,
> Vladimir
>
>