[FFmpeg-user] How does ffmpeg decides how many threads to use for vmaf

[tarun singhal]

On Tue, 22 Oct 2024 at 21:54, Srikanth Kotagiri <srikanthk at gmail.com> wrote:

> On Mon, Oct 21, 2024 at 11:39 PM tarun singhal <tsinghal18 at gmail.com>
> wrote:
>
> > I have specified thread count as 32
> >
> > For 20 min video duration - I was able to get 1x speed
> >
> > But for 2.2hr video duration it took 12 hrs, hence lesser speed using
> same
> > ffmpeg command and same underlying infrastructure
> >
> >
> > Hence I am curious, What are the factors which helps ffmpeg decide how
> many
> > threads to use for a particular vmaf processing
> >
> >
> > Thanks
> >
> > Tarun
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> Can you share the command line you used and the full logs?
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ffmpeg -i transcodedA.mp4 -i sourceA.mxf -filter_complex
>
"[0:v][1:v]scale2ref=flags=bicubic[encoded][source];[source]format=pix_fmts=yuv420p,setpts=PTS-STARTPTS[source2];[encoded]setpts=PTS-STARTPTS[encoded1];[encoded1][source2]libvmaf=feature='name=psnr|name=float_ssim|name=float_ms_ssim':n_threads=32:log_fmt=json:log_path=A0-10.json"
> -f null -