Change #239983

Comments

avfilter/vf_thumbnail: unroll and use multiple histograms
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.

Changed files

• libavfilter/vf_thumbnail.c