[FFmpeg-devel] [PATCH] avfilter/vf_thumbnail: unroll and use multiple histograms
Niklas Haas
ffmpeg at haasn.xyz
Wed Jul 16 11:17:52 EEST 2025
On Sat, 12 Jul 2025 13:38:37 +0200 Niklas Haas <ffmpeg at haasn.xyz> wrote:
> From: Niklas Haas <git at haasn.dev>
>
> This naive hist[p[x]]++ loop suffers badly when there are large regions of
> identical values in the image, because of store-to-load forwarding delay.
>
> Splitting up the histogram into four "parallel" histograms and processing
> them one at a time speeds things up significantly, about 40% on my end.
Merging this patch soon.
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