[FFmpeg-devel] [PATCH 10/10] lavfi/vf_scale: pass the thread count to the scaler

[Michael Niedermayer]

On Sun, Aug 29, 2021 at 06:48:36PM +0200, Anton Khirnov wrote:
> Quoting Michael Niedermayer (2021-08-09 22:30:06)
> > On Sun, Aug 08, 2021 at 07:29:41PM +0200, Anton Khirnov wrote:
> > > ---
> > >  libavfilter/vf_scale.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/libavfilter/vf_scale.c b/libavfilter/vf_scale.c
> > > index b62fb37d4b..14e202bf77 100644
> > > --- a/libavfilter/vf_scale.c
> > > +++ b/libavfilter/vf_scale.c
> > > @@ -542,6 +542,7 @@ static int config_props(AVFilterLink *outlink)
> > >              av_opt_set_int(*s, "sws_flags", scale->flags, 0);
> > >              av_opt_set_int(*s, "param0", scale->param[0], 0);
> > >              av_opt_set_int(*s, "param1", scale->param[1], 0);
> > > +            av_opt_set_int(*s, "threads", ff_filter_get_nb_threads(ctx), 0);
> > >              if (scale->in_range != AVCOL_RANGE_UNSPECIFIED)
> > >                  av_opt_set_int(*s, "src_range",
> > >                                 scale->in_range == AVCOL_RANGE_JPEG, 0);
> > > -- 
> > > 2.30.2
> > 
> > breaks:
> > ./ffmpeg -i ~/tickets/1012/IV50_random_points.avi  -threads 5 -y file1012.avi
> > 
> > it contains horizontal bright green lines
> 
> Should be fixed with the updated patches I sent just now.
> 

> That said, I think the special 410->420 scaler should be dropped - its
> output fundamentally depends on how the slices are submitted. Given that

hmm, iam not sure i understand the issue you describe.
Is this because the 410->420 scaler interpolates the chroma and to do so
it has to handle the image borders differently?
That is done by the standard code path too and would be the expected
"high quality" thing to do. It is more noticable with 410 because chroma
is subsampled so extreemly so artifacts are more vissible but for best
quality we should interpolate all the chroma subsample convertions
by default.
But maybe there is some other issue in this converter which i forgot ...


> 410 is a pretty obscure format, it's unlikely anyone needs a super-fast
> non-exact conversion.

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When you are offended at any man's fault, turn to yourself and study your
own failings. Then you will forget your anger. -- Epictetus
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