[FFmpeg-devel] [PATCH] avformat/apngenc: use the stream parameters extradata if no updated one is made available

Andreas Cadhalpun andreas.cadhalpun at googlemail.com
Tue Nov 1 18:17:27 EET 2016

On 01.11.2016 17:06, James Almer wrote:
> On 11/1/2016 12:54 PM, Andreas Cadhalpun wrote:
>> What I like about the approach of using the private extra_data context buffer is
>> that is is quite obvious where it is set. On the other hand the codecpar
>> extradata can be set anywhere, which makes it difficult to understand/debug.
>> The very bug this patch would fix is an excellent example of that.
>> So I'd rather convert the apngdec demuxer to pass the extradata as side data.
>> I'll send a patch doing that.
> Is it worth doing that? This patch is pretty simple and solves the issue for
> both encoder and demuxer.
> With it the muxer will use either the original extradata or any new one sent
> within a packet. In both cases, the muxer uses its own buffer to keep it.
> I don't think changing the demuxer to append the same extradata it already
> sent during init() again with a packet makes sense. It's extra complexity
> for no gain.

Not again, but instead, as the extradata is then only transferred as side data.
That way it is again consistent between demuxer/decoder and encoder/muxer.

Best regards,

More information about the ffmpeg-devel mailing list