[FFmpeg-devel] [PATCH] Implemented arrange feature to convert from low timebase formats to high timebase

[Michael Niedermayer]

On Wed, Oct 17, 2012 at 07:14:07PM +0400, Roman Arutyunyan wrote:
> 2012/10/17 Michael Niedermayer <michaelni at gmx.at>
> 
> > On Wed, Oct 17, 2012 at 11:34:58AM +0400, Roman Arutyunyan wrote:
> > [...]
> > >  AVRational av_codec_get_pkt_timebase         (const AVCodecContext
> > *avctx);
> > > diff --git a/libavformat/utils.c b/libavformat/utils.c
> > > index 05c4b7f..0b59eeb 100644
> > > --- a/libavformat/utils.c
> > > +++ b/libavformat/utils.c
> > > @@ -3498,6 +3498,14 @@ static int compute_pkt_fields2(AVFormatContext
> > *s, AVStream *st, AVPacket *pkt){
> > >      if(pkt->pts == AV_NOPTS_VALUE && pkt->dts != AV_NOPTS_VALUE &&
> > delay==0)
> > >          pkt->pts= pkt->dts;
> > >
> > > +    if (st->codec->arrange_threshold && pkt->dts != AV_NOPTS_VALUE &&
> > st->pts.val != AV_NOPTS_VALUE){
> > > +        int64_t diff = pkt->dts - st->pts.val;
> > > +        int64_t maxdiff = av_rescale(st->codec->arrange_threshold,
> > st->time_base.den, AV_TIME_BASE * (int64_t)st->time_base.num);
> > > +        av_dlog(s, "Arrange dts=%"PRId64" cur_dts=%"PRId64"
> > diff=%"PRId64" maxdiff=%"PRId64"\n", pkt->dts, st->pts.val, diff, maxdiff);
> > > +        if (diff > -maxdiff && diff < maxdiff)
> > > +            pkt->dts = pkt->pts = AV_NOPTS_VALUE;
> > > +    }
> >
> > this doesnt look correct. The correction should be done where the
> > problem is currently introduced. As done here , ffmpeg.c would send
> > some timestamps to the muxer but the muxer would use different
> > timestamps. its ffmpeg*.c or a common utility function used by
> > ffmpeg*.c where the correction should be done.
> >
> > Currently timestamps are rounded toward "nearest", what should
> > instead be done, is to round toward the exact duration + last_time
> > see av_get_audio_frame_duration() to find the exact frame duration.
> >
> 
> I'm absolutely agree with you. The reason why I've done that way is there's
> nothing
> that looks like last_time on earlier stages of frame processing (ffmpeg.c).

if at the location where the issue is introduced there really is no
last timestamp variable then its quite easy to add one.


[...]

thanks
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable
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