[FFmpeg-devel] Color quantization for GIF

Clément Bœsch u at pkh.me
Sun Jan 25 20:38:36 CET 2015

On Sun, Jan 25, 2015 at 07:55:17PM +0100, Clément Bœsch wrote:
> Hi folks,
> I've been trying to improve GIF support even more recently. This is the result:
> http://lucy.pkh.me/gone-nutty-current.gifhttp://lucy.pkh.me/gone-nutty.gif

I added more here: http://lucy.pkh.me/gif-experiment/ with other dithering
(in what is available currently):

total 119M
-rw-r--r-- 1 ux ux 13M Jan 25 20:28 out-current-ad.gif
-rw-r--r-- 1 ux ux 41M Jan 25 20:28 out-current-ed.gif
-rw-r--r-- 1 ux ux 13M Jan 25 20:28 out-current.gif
-rw-r--r-- 1 ux ux 14M Jan 25 20:28 out-current-xd.gif
-rw-r--r-- 1 ux ux 40M Jan 25 20:28 out-dither.gif

total 77M
-rw-r--r-- 1 ux ux 6.5M Jan 25 20:19 out-current-ad.gif
-rw-r--r-- 1 ux ux  29M Jan 25 20:19 out-current-ed.gif
-rw-r--r-- 1 ux ux 6.1M Jan 25 20:18 out-current.gif
-rw-r--r-- 1 ux ux 7.3M Jan 25 20:19 out-current-xd.gif
-rw-r--r-- 1 ux ux  29M Jan 25 20:19 out-dither.gif

total 111M
-rw-r--r-- 1 ux ux 12M Jan 25 20:22 out-current-ad.gif
-rw-r--r-- 1 ux ux 36M Jan 25 20:22 out-current-ed.gif
-rw-r--r-- 1 ux ux 14M Jan 25 20:22 out-current.gif
-rw-r--r-- 1 ux ux 14M Jan 25 20:22 out-current-xd.gif
-rw-r--r-- 1 ux ux 38M Jan 25 20:22 out-dither.gif

So indeed, with the heckbert/floyd-steinburg dithering I implemented in
paletteuse, the results are very similar in size with error diffusion

The quality is IMO better with the palette though, except for a bug in BBB
where it seems the palette has no black (so the opening fade in looks like

I used the following for testing:


./ffmpeg -i $1 -vf trim=start=$2:end=$3,palettegen -y palette.png


./ffmpeg -i $1                -lavfi $filt                     -y out-current.gif
./ffmpeg -i $1                -lavfi $filt:sws_dither=ed       -y out-current-ed.gif
./ffmpeg -i $1                -lavfi $filt:sws_dither=a_dither -y out-current-ad.gif
./ffmpeg -i $1                -lavfi $filt:sws_dither=x_dither -y out-current-xd.gif
./ffmpeg -i $1 -i palette.png -lavfi $filt,paletteuse          -y out-dither.gif

Clément B.
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