[FFmpeg-devel] [PATCH] h264 ticks and time base

[Michael Niedermayer]

On Fri, Jun 19, 2009 at 11:15:46PM -0700, Baptiste Coudurier wrote:
> Michael Niedermayer wrote:
> > On Wed, Jun 17, 2009 at 04:58:34PM -0700, Baptiste Coudurier wrote:
> >> Michael Niedermayer wrote:
> >>> On Sun, Jun 14, 2009 at 10:42:11PM -0700, Baptiste Coudurier wrote:
> >>>> Hi,
> >>>>
> >>>> 1) Set avctx time_base in h264 parser.
> >>>> 2) Set avctx ticks_per_frame in h264 decoder.
> >>>>
> >>>> I don't get this code in decode_init in h264.c
> >>>>
> >>>>     reset_sei(h);
> >>>>     if(avctx->codec_id == CODEC_ID_H264){
> >>>>         if(avctx->ticks_per_frame == 1){
> >>>>             s->avctx->time_base.den *=2;
> >>>>         }
> >>>>         avctx->ticks_per_frame = 2;
> >>>>     }
> >>>>     return 0;
> >>>>
> >>>> avctx->ticks_per_frame is not set before calling the decoder
> >>>> in any case. Should that be removed ?
> >>> what do you mean by "that" ?
> >> the if(avctx->ticks_per_frame == 1)
> > 
> > i think it was needed because the codec might be ininted then closed and
> > then ininted again, but i may misremember
> 
> Oh, hackish isn't it ?

do you have a better idea?


> Nothing seems to set ticks_per_frame to 1 in h264 though.

no, 1 is the default
the first init of h264 sets it to 2 and doubles the time_base
the second must not double time_base again, the == 1 check
avoids it
if a demuxer meant to set the field rate instead of the frame rate
it can set ticks_per_frame to 2

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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