High quality GIF with FFmpeg • Hacker News Board

Re: High quality GIF with FFmpeg

#11

Post by lnanek2 » Mon, Mar 16, 2015, 6:51 PM UTC

The improved screenshots do look quite improved, with less screen door effect. Nice.

Re: High quality GIF with FFmpeg

#12

Post by quotedmycode » Mon, Mar 16, 2015, 6:52 PM UTC

So it's using a simple Median Cut quantization... which is okay, but you can get great results using an octree quantizer, and without dithering. Dithering kills your compression savings in GIF so you'd want to avoid it if possible. In any case, you can see the difference a better quantizer makes here:

http://www.leptonica.com/color-quantization.html

Re: High quality GIF with FFmpeg

#13

Post by bithush » Mon, Mar 16, 2015, 6:57 PM UTC

imaginenore wrote: post #6

And to complete the circle, run the gif through Gfycat and check out the mindblowing bandwidth savings: http://gfycat.com/IllustriousHairyGermanpinscher GIF: 1 MB Video: 73k

Indeed. While this is a nice hack, GIF really needs to just die now.

Re: High quality GIF with FFmpeg

#14

Post by ux » Mon, Mar 16, 2015, 7:12 PM UTC

quotedmycode wrote: post #12

So it's using a simple Median Cut quantization... which is okay, but you can get great results using an octree quantizer, and without dithering. Dithering kills your compression savings in GIF so you'd want to avoid it if possible. In any case, you can see the difference a better quantizer makes here: http://www.leptonica.com/color-quantization.html

The median cut quantization with a few tweaks (using the the variance typically - see the post for more) actually gives very good results. According to your post, it seems it will not provide much better results with Octree, if any. That calls for testing though (I won't but feel free to, the infrastructure is ready for you to hack in), as improvements are very welcome.

Concerning the dithering, you can disable it (dither=none). And indeed, it kills the compression, mainly when using animation, that's why I added the diff_mode option typically (see at the end of the post).

Re: High quality GIF with FFmpeg

#15

Post by ux » Mon, Mar 16, 2015, 7:14 PM UTC

artursapek wrote: post #3

I use this shell script for generating gifs out of .mov files: https://gist.github.com/artursapek/5b3d15ecac5ff75593c4 I can probably improve it further by using some of what's in this article, but it's already faster and better than any online tool I've found.

> (convert -delay 5 -loop 0 $tmp_dir/ffout*.png $2) >& /dev/null

So using ImageMagick for this... How is this memory wise BTW? (all frames are in memory at once or not?)

Re: High quality GIF with FFmpeg

#16

Post by ux » Mon, Mar 16, 2015, 7:19 PM UTC

theophrastus wrote: post #2

This is an interesting discussion, thank you. It would be great to see it compared with the parallel ImageMagick methods: http://www.imagemagick.org/Usage/anim_opt/

ImageMagick is very popular, but apparently the algorithms in pngquant gives excellent results. Don't forget to include it if you do comparisons with the different solutions.

Also keep in mind that the compression efficiency and quality depends a lot on the content and how you play with the encoding options (how surprising...). I tried to cover most of the cases in my post, but make sure you are "fluent" with the other tools as well to make an objective comparison.

Overall, I think FFmpeg trump-card is that it includes the whole stack; timing, decoding, filtering, encoding, everything is in.

Re: High quality GIF with FFmpeg

#17

Post by leeoniya » Mon, Mar 16, 2015, 7:20 PM UTC

quotedmycode wrote: post #12

So it's using a simple Median Cut quantization... which is okay, but you can get great results using an octree quantizer, and without dithering. Dithering kills your compression savings in GIF so you'd want to avoid it if possible. In any case, you can see the difference a better quantizer makes here: http://www.leptonica.com/color-quantization.html

here's how my quantizer does: full-color, undithered, floyed-dithered: http://imgur.com/a/lrLTd#0

repo: https://github.com/leeoniya/RgbQuant.js

demos: http://o-0.me/RgbQuant/

this image is actually a pretty poor example of quantization, it's too easy. full color gradients give a much better indicator of behavior, quality and performance.

if you really are interested in different algorithms, check this out: http://www.codeproject.com/Articles/66341/A-Simple-Yet-Quite...

error-diffusion dithering explained (and kernels): http://www.tannerhelland.com/4660/dithering-eleven-algorithm...

Re: High quality GIF with FFmpeg

#18

Post by acheron » Mon, Mar 16, 2015, 7:21 PM UTC

imaginenore wrote: post #6

And to complete the circle, run the gif through Gfycat and check out the mindblowing bandwidth savings: http://gfycat.com/IllustriousHairyGermanpinscher GIF: 1 MB Video: 73k

I like to imagine going back in time to 2005-06 and telling myself "You know what's going to come back in a big way? Animated GIFs!"

I wouldn't believe myself whatsoever.

Re: High quality GIF with FFmpeg

#19

Post by sorenjan » Mon, Mar 16, 2015, 7:31 PM UTC

Nice article and good job implementing it. I would have preferred a small explanation of the filter graph option (-lavfi), but I guess that's outside the scope of the post.

Re: High quality GIF with FFmpeg

#20

Post by IgorPartola » Mon, Mar 16, 2015, 7:34 PM UTC

dublinben wrote: post #10

imaginenore wrote: post #6

And to complete the circle, run the gif through Gfycat and check out the mindblowing bandwidth savings: http://gfycat.com/IllustriousHairyGermanpinscher GIF: 1 MB Video: 73k

Yes please. Let's leave GIF in the 20th Century, where it belongs.

If only iOS (and Android?) allowed you to play inline videos the way you can on the desktop, and the way they play animated GIF's inline. Besides allowing us to adopt video throughout and save on bandwidth and have better video quality, this will be a huge productivity boost to developers: we can finally stop having the GIF vis JIF pronunciation debate.