[FFmpeg-devel] [PATCH] fix convergence_duration default value

[Aurelien Jacobs]

On Thu, Jun 17, 2010 at 02:11:25AM +0200, Michael Niedermayer wrote:
> On Tue, Jun 15, 2010 at 11:19:54PM +0200, Aurelien Jacobs wrote:
> > Hi,
> > 
> > av_init_packet() currently initialize pkt->convergence_duration to 0.
> > This seems wrong. According to the documentation of convergence_duration:
> >     * Is AV_NOPTS_VALUE if unknown.
> > Moreover, av_parser_init() is following the documentation and initialize
> > convergence_duration to AV_NOPTS_VALUE.
> > I propose to fix av_init_packet() so that it also initialize
> > convergence_duration to AV_NOPTS_VALUE.
> 
> if its set to AV_NOPTS_VALUE by default then every demuxer has to
> override it to 0. if its 0 by default only demuxers where its acrually
> not 0 (or could b non 0) have to override

I'm not sure that I understand this correctly.
In my understanding, in most cases, convergence_duration can only be set
to 0 for actual key_frame. It must be different than 0 for P and B
frames.
So all demuxers supporting non-key frames would have to set
convergence_duration if its default value is 0 (none of them does it
right now, leaving convergence_duration to an incorrect value).
On the other end, I don't really see the point of having
convergence_duration set to 0 for key frames, as we already have this
information carried by pkt.flags == AV_PKT_FLAG_KEY.

So a default convergence_duration set to 0 seems useless and needs to be
overriden in many demuxers.
On the other end, if setting default convergence_duration to
AV_NOPTS_VALUE, it would need to be overriden only in a very few cases
(H264 SEI recovery point, and so on...) and wouldn't loose any
information.

Did I missed something ?

Aurel