[FFmpeg-trac] #6368(avformat:new): audio_preload broken

[FFmpeg]

#6368: audio_preload broken
-------------------------------------+-------------------------------------
             Reporter:  alex3d       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  avformat     |                  Version:  git-
             Keywords:               |  master
  audio_preload                      |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 When audio_preload option is set output media stream a/v interleaving is
 broken because of "wrong sign issue" in interleave_compare_dts.
 I'm willing to provide patch solving this issue and also enabling audio
 stream shift in both directions (currently audio_preload is 0-int_max).
 Probably audio_preload can be renamed to something like audio_shift? (it
 seems no one uses audio_preload option because of this issue)

 libavformat/mux.c: (master branch)
 {{{
 static int interleave_compare_dts(AVFormatContext *s, AVPacket *next,
                                   AVPacket *pkt)
 {
     AVStream *st  = s->streams[pkt->stream_index];
     AVStream *st2 = s->streams[next->stream_index];
     int comp      = av_compare_ts(next->dts, st2->time_base, pkt->dts,
                                   st->time_base);
     if (s->audio_preload && ((st->codecpar->codec_type ==
 AVMEDIA_TYPE_AUDIO) != (st2->codecpar->codec_type == AVMEDIA_TYPE_AUDIO)))
 {
         int64_t ts = av_rescale_q(pkt ->dts, st ->time_base,
 AV_TIME_BASE_Q) - s->audio_preload*(st ->codecpar->codec_type ==
 AVMEDIA_TYPE_AUDIO);
         int64_t ts2= av_rescale_q(next->dts, st2->time_base,
 AV_TIME_BASE_Q) - s->audio_preload*(st2->codecpar->codec_type ==
 AVMEDIA_TYPE_AUDIO);
         if (ts == ts2) {
             ts= ( pkt ->dts* st->time_base.num*AV_TIME_BASE -
 s->audio_preload*(int64_t)(st ->codecpar->codec_type ==
 AVMEDIA_TYPE_AUDIO)* st->time_base.den)*st2->time_base.den
                -( next->dts*st2->time_base.num*AV_TIME_BASE -
 s->audio_preload*(int64_t)(st2->codecpar->codec_type ==
 AVMEDIA_TYPE_AUDIO)*st2->time_base.den)* st->time_base.den;
             ts2=0;
         }
         comp= (ts>ts2) - (ts<ts2); ///////// there should be (ts2>ts) -
 (ts2<ts) obviously
     }

     if (comp == 0)
         return pkt->stream_index < next->stream_index;
     return comp > 0;
 }


 }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/6368>
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