[FFmpeg-devel] [PATCH] Animated GIF Support

[Paul B Mahol]

On 10/12/12, Vitaliy Sugrobov <vsugrob at hotmail.com> wrote:
>
>> How will this work with seeking?
>>
>> This means that first frame is keyframe and any other frame with
>> transparency is not.> I think that right place to handle this is not in
>> decoder but from user.
>>
>> AFAIK mplayer should handle it and ffplay not.
>
> According to gif spec any
> subsequent frame depends on all previous frames. And this is not only
> because of transparency, the other reason is variable frame dimensions. In
> more detail: gif header provides us initial image dimensions { width,
> height }. Then, any subsequent frame specifies its { x, y, width, height }
> characteristics within bounds of the canvas, which means than only portion
> of the canvas is updated. Thus first frame might be considered as a
> keyframe and any other frame with or without transparency is not a
> keyframe. So there is no way to seek frame F without calculating preceding
> frames A, B, C, D and E. 		 	   		

Then mark packets/frames as such in demuxer/decoder.

Can you please quote correctly next time.