On Sun, May 06, 2018 at 04:53:54PM +0200, Moritz Barsnick wrote:
> On Sun, May 06, 2018 at 13:40:58 +0200, Clément Bœsch wrote:
> > Overall speed appears to be 1.1x faster with no noticeable quality impact.
>
> Probably platform dependant?
>
> > struct weighted_avg {
> > -double total_weight;
> > -double sum;
> > +float total_weight;
> > +float sum;
> > };
>
> I believe these calculaions in nlmeans_plane() will promote to double
> before being cast back to float:
>
>// Also weight the centered pixel
> wa->total_weight += 1.0;
> wa->sum += 1.0 * src[y*src_linesize + x];
>
> (At least the second one. The first one - just an assignment of a
> constant - is covered by the preprocessor, IIUC.) They need to use
> "1.0f".
>
It doesn't really matter here actually, in "lavfi/nlmeans: move final
weighted averaging out of nlmeans_plane" you can see that this code
represents 0.24% of the CPU time. I fixed it locally anyway, thanks.
> (There are others, but only in init(), which don't matter for
> performance.)
Yeah, I left these to double on purpose.
--
Clément B.
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