[FFmpeg-devel] [PATCH v1] lavf/mov: Fix timestamp rescale on sidx atom

[mypopy at gmail.com]

On Tue, Sep 24, 2019 at 12:38 PM Jun Li <junli1026 at gmail.com> wrote:
>
> On Thu, Aug 15, 2019 at 1:02 AM mypopy at gmail.com <mypopy at gmail.com> wrote:
>
> > On Thu, Aug 15, 2019 at 12:49 PM Jun Li <junli1026 at gmail.com> wrote:
> > >
> > > On Thu, Jun 20, 2019 at 2:02 AM Jun Li <junli1026 at gmail.com> wrote:
> > >
> > > >
> > > >
> > > > On Tue, May 21, 2019 at 1:05 AM Jun Li <junli1026 at gmail.com> wrote:
> > > >
> > > >>
> > > >>
> > > >> On Thu, May 16, 2019 at 1:00 AM Jun Li <junli1026 at gmail.com> wrote:
> > > >>
> > > >>>
> > > >>>
> > > >>> On Sun, May 12, 2019 at 7:44 PM Jun Li <junli1026 at gmail.com> wrote:
> > > >>>
> > > >>>>
> > > >>>>
> > > >>>> On Fri, May 10, 2019 at 7:25 PM Jun Li <junli1026 at gmail.com> wrote:
> > > >>>>
> > > >>>>>
> > > >>>>> On Thu, May 9, 2019 at 2:08 AM Jun Li <junli1026 at gmail.com> wrote:
> > > >>>>>
> > > >>>>>> Fix #5090
> > > >>>>>> Fix the timestamp rescale issue, from sidx timebase to
> > > >>>>>> stream's timebase.
> > > >>>>>> ---
> > > >>>>>>  libavformat/mov.c | 2 +-
> > > >>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >>>>>>
> > > >>>>>> diff --git a/libavformat/mov.c b/libavformat/mov.c
> > > >>>>>> index 78f692872b..d058855e6c 100644
> > > >>>>>> --- a/libavformat/mov.c
> > > >>>>>> +++ b/libavformat/mov.c
> > > >>>>>> @@ -5017,7 +5017,7 @@ static int mov_read_sidx(MOVContext *c,
> > > >>>>>> AVIOContext *pb, MOVAtom atom)
> > > >>>>>>              return AVERROR_PATCHWELCOME;
> > > >>>>>>          }
> > > >>>>>>          avio_rb32(pb); // sap_flags
> > > >>>>>> -        timestamp = av_rescale_q(pts, st->time_base, timescale);
> > > >>>>>> +        timestamp = av_rescale_q(pts, timescale, st->time_base);
> > > >>>>>>
> > > >>>>>>          index = update_frag_index(c, offset);
> > > >>>>>>          frag_stream_info = get_frag_stream_info(&c->frag_index,
> > > >>>>>> index, track_id);
> > > >>>>>> --
> > > >>>>>> 2.17.1
> > > >>>>>>
> > > >>>>>
> > > >>>>> Ping
> > > >>>>>
> > > >>>>
> > > >>>> This change is for fix the issue of calculating sidx_pts.
> > > >>>> Sidx box has "earliest_presentation_time", used as pts of  the
> > referent
> > > >>>> track, sidx also has timescale field.
> > > >>>> So the operation should convert from sidx's timescale to track's
> > > >>>> timescale, this patch is for addressing this, as well as fixing
> > #5090.
> > > >>>>
> > > >>>> Of course this is based on my understanding, so please correct me
> > if I
> > > >>>> am wrong. Thanks !
> > > >>>>
> > > >>>>
> > > >>> Ping.
> > > >>> I believe this is a bug and triggered whenever sidx box's timescale
> > is
> > > >>> different from track's timescale.
> > > >>> Created this kind of content and verified that ffplay couldn't play
> > > >>> while VLC plays well.
> > > >>> Then I checked VLC's implementation:
> > > >>>
> > > >>>
> > https://github.com/videolan/vlc/blob/5609c1b41d6fbca6323103619c6139caf7bc9e6e/modules/demux/mp4/mp4.c#L4735
> > > >>>
> > > >>> Hope someone could help to have a review ? Thanks ! :)
> > > >>>
> > > >>> Best Regards,
> > > >>> -Jun
> > > >>>
> > > >>>
> > > >>>> Best Regards,
> > > >>>> Jun
> > > >>>>
> > > >>>
> > > >> Ping x 3
> > > >>
> > > >
> > > > Ping x 4.
> > > > I believe this is an obvious bug and happened whenever sidx box's
> > > > timescale is different from track's timescale.
> > > > I created this kind of content and verified that ffplay couldn't play
> > > > while VLC plays well.
> > > > This is  VLC's implementation:
> > > >
> > > >
> > https://github.com/videolan/vlc/blob/5609c1b41d6fbca6323103619c6139caf7bc9e6e/modules/demux/mp4/mp4.c#L4735
> > > >
> > >
> > > Ping x 5
> > Tested and verified with ffplay/ffprobe, now the sample video DTS is
> > monotonically increasing without wrap around.
> > _______________________________________________
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>
>
> Ping x 6
If no other comments, will apply after 24 hours, Thanks