[FFmpeg-devel] Animated GIF support

Don Moir donmoir at comcast.net
Thu Dec 20 12:15:50 CET 2012

----- Original Message ----- 
From: "Paul B Mahol" <onemda at gmail.com>
To: "FFmpeg development discussions and patches" <ffmpeg-devel at ffmpeg.org>
Sent: Thursday, December 20, 2012 5:26 AM
Subject: Re: [FFmpeg-devel] Animated GIF support

> On 12/19/12, Don Moir <donmoir at comcast.net> wrote:
>> I don't use ffmpeg for gif's but did a comparison of latest gif patches and
>> found some problems with ffmpeg animtated gif support.
>> Several had no transparency which should have been transparent and hears a
>> couple samples of that:
>> http://sms.pangolin.com/temp/chompy.gif  - shows gray background
> With what program? What background should really be?
>> http://sms.pangolin.com/temp/cool.gif  - shows black background

Where its showing the background color it should be transparent. Any program I tested it in appears ok. If you just drag them into 
firefox it will show a white background because it has to be something. But it wont be gray or black since those areas should be 

>> This one gets transparency right but seems to have the wrong delay. The
>> delay value I get is 15 which is 150ms. With ffmpeg its way
>> to fast.
>> http://sms.pangolin.com/temp/crazy.gif  - 2 frames and animates too fast
> How are you sure that is gif demuxer/decoder fault?
> Its delay is set correctly, it is player bug to ignore last frame duration.

That could be I will double check.

>> This one caused me to crash in avcodec_decode_video2:
>> http://sms.pangolin.com/temp/heart.gif
> Reproduced. Will explore it. Thanks.
>> I have many more gifs that may cause problems and if you decide to fix the
>> above I will test it some more. All of the above
>> displayed normally outside of ffmpeg.
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