[FFmpeg-devel] [PATCH] avcodec[/format]/webpenc: use WebPAnimEncoder API to generate animated WebP

James Almer jamrial at gmail.com
Tue Apr 28 02:27:23 CEST 2015

On 27/04/15 9:02 PM, Michael Niedermayer wrote:
> Ok, so the patch adds many #ifs to both the muxer and
> encoder, and there are more changes in the encoder than the muxer
> the commit message which is 1 single line only speaks about the encoder
> and the patch is only about the muxer.
> Did i understand it correctly this time ?
> assuming iam not entirely wrong here.
> First question is what does the patch actually try to achive ?
> replace a native muxer by a new external dependancy ?
> if so, why would we want that ?
> And assuming we do want that (which iam not sure we do)
> why are there changes in the encoder ?

With this patch, if a new enough libwebpmux version is available, both the encoding 
and muxing are done by libwebp all within libavcodec. The changes to lavf muxer are 
so, in case the above happens, it acts as a raw muxer of sorts.

The muxing as done by libwebpmux is more efficient than our current native one. As 
Urvang mentioned earlier, among other things it stores only the differences between 
frames rather than the entire frame every time.

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