[FFmpeg-devel] [FFmpeg-cvslog] avformat/webpenc: don't assume animated webp streams will have more than one packet

[James Almer]

On 4/16/2021 11:36 AM, Carl Eugen Hoyos wrote:
> 
> 
>> Am 16.04.2021 um 16:15 schrieb James Almer <git at videolan.org>:
>>
>> ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Sat Apr 10 22:53:34 2021 -0300| [55d667d86af7d13fc5aa2b4071a5b97eb10e2da6] | committer: James Almer
>>
>> avformat/webpenc: don't assume animated webp streams will have more than one packet
>>
>> The libwebp_animencoder returns a single packet with the entire animated
>> stream, as that's what the external library produces. As such, only ensure the
>> stream was produced by said encoder (or propagated by a demuxer, once support
>> is added) when attempting to write the requested loop value.
>>
>> Fixes ticket #9179.
>>
>> Signed-off-by: James Almer <jamrial at gmail.com>
>>
>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=55d667d86af7d13fc5aa2b4071a5b97eb10e2da6
>> ---
>>
>> libavformat/webpenc.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavformat/webpenc.c b/libavformat/webpenc.c
>> index ed8325c02d..ca4ffc4e2d 100644
>> --- a/libavformat/webpenc.c
>> +++ b/libavformat/webpenc.c
>> @@ -172,7 +172,7 @@ static int webp_write_trailer(AVFormatContext *s)
>>      WebpContext *w = s->priv_data;
>>
>>      if (w->using_webp_anim_encoder) {
>> -        if ((w->frame_count > 1) && w->loop) {  // Write loop count.
>> +        if (w->loop) {  // Write loop count.
>>              avio_seek(s->pb, 42, SEEK_SET);
>>              avio_wl16(s->pb, w->loop);
>>          }
> 
> I wonder now why you are asking for reviews, more so given that you tend to block patches you consider not good enough.
> 
> Carl Eugen

I sent this patch a week ago. The only comment was your suggestion to 
move the loop count writing to write_packet(). That's still a 
possibility, but it's orthogonal to the regression this patch fixed, 
given it's a change to enable this muxer to work with non-seekable output.