[FFmpeg-devel] [PATCH v5 1/4 v7] lavf/avienc: Add support for palette side data

Mats Peterson matsp888 at yahoo.com
Sat Mar 5 21:37:57 CET 2016

On 03/05/2016 05:54 PM, Reimar Döffinger wrote:
> On Sat, Mar 05, 2016 at 02:32:56PM +0100, Mats Peterson wrote:
>> On 03/05/2016 02:24 PM, Mats Peterson wrote:
>>> The original toon.avi doesn't contain xxpc chunks at keyframes either,
>>> if that can be of any comfort. It only contains two xxpc chunks, at
>>> that. If you're able to invent something nice regarding palette changes
>>> on keyframes, please go ahead. But please add what's available in the
>>> meantime.
>>> Mats
>> In my book it should be up to the demuxer/decoder to keep track of previous
>> palettes. You said yourself that no xxpc chunks should be included if they
>> are identical to the first palette.
> Define "previous".
> What you suggests means that for a 1 GB video, if you want to see the
> only the last frame the demuxer would _always_ have to parse the whole 1GB
> just to make sure it has the last palette.
> Thus the desire to always have a complete palette included for
> "keyframes", which exist exactly so you can start playing
> without parsing the whole file first.
> Obviously patches don't have to solve every problem from the start,
> but then again half the time to revise them faster than anyone can check
> them...
> Btw. sorry, maybe Michael manages, but I at least won't be able to
> even read, much less properly follow all your emails if you
> write that many.
> So either you have to slow down or wait a bit longer for us
> to manage to (find the right version of) and apply patches...
> Regards,
> Reimar
> _______________________________________________

Well, Reimar, I do agree on this after all. That statement about letting 
the demuxer handle it was rather incorrect. A fit of bad patience, if 
you will. But the fact is that the original toon.avi file there only 
contains two xxpc chunks, so it hardly follows the "xxpc chunk on 
keyframe" rule.


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