> -----Original Message----- > From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of > Clément Bœsch > Sent: Sunday, October 30, 2022 6:58 PM > To: ffmpeg-devel@ffmpeg.org > Cc: softwo...@hotmail.com; Clément Bœsch <u...@pkh.me> > Subject: [FFmpeg-devel] [PATCH] Revert "avfilter/vf_palette(gen|use): > support palettes with alpha" > > This reverts commit dea673d0d548c864ec85f9260d8900d944ef7a2a. > > This change cannot work for several reasons, the most obvious ones > are: > > - the alpha is being part of the scoring of the color difference, > even > though we can not interpret the alpha as part of the perception of > the > color (we don't even know if it's premultiplied or postmultiplied) > - the colors are averaged with their alpha value which simply cannot > work > > The command proposed in the original thread of the patch actually > produces a completely broken file: > > ffmpeg -y -loglevel verbose -i fate-suite/apng/o_sample.png - > filter_complex > "split[split1][split2];[split1]palettegen=max_colors=254:use_alpha=1[ > pal1];[split2][pal1]paletteuse=use_alpha=1" -frames:v 1 out.png > > We can see that many color pixels are off, but more importantly some > colors have a random alpha value: https://imgur.com/eFQ2UK7 > > I don't see any easy fix for this unfortunately, the approach appears > to > be flawed by design. > ---
At the time of submission I did a lot of experiments and the results seemed to be very useful: https://gist.github.com/softworkz/deef5c2a43d3d629c3e17f9e21544a8f softworkz _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
