Re: [FFmpeg-devel] [FFmpeg-cvslog] avfilter/vf_tpad: if there is no frame to clone return early

[Paul B Mahol <onemda@gmail.com>]

On Thu, Feb 24, 2022 at 10:36 PM Thierry Foucu <tfoucu@gmail.com> wrote:

> On Thu, Feb 24, 2022 at 1:28 PM Paul B Mahol <onemda@gmail.com> wrote:
>
> > On Thu, Feb 24, 2022 at 10:12 PM Thierry Foucu <tfoucu@gmail.com> wrote:
> >
> > > On Thu, Feb 24, 2022 at 12:30 PM Paul B Mahol <git@videolan.org>
> wrote:
> > >
> > > > ffmpeg | branch: master | Paul B Mahol <onemda@gmail.com> | Thu Feb
> 24
> > > > 20:32:41 2022 +0100| [3715f2f8643695940582ce040b7a052cccfb9db2] |
> > > > committer: Paul B Mahol
> > > >
> > > > avfilter/vf_tpad: if there is no frame to clone return early
> > > >
> > > > >
> > > >
> > >
> >
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3715f2f8643695940582ce040b7a052cccfb9db2
> > > > ---
> > > >
> > > >  libavfilter/vf_tpad.c | 5 +++++
> > > >  1 file changed, 5 insertions(+)
> > > >
> > > > diff --git a/libavfilter/vf_tpad.c b/libavfilter/vf_tpad.c
> > > > index e5acece1e4..120dbcb4d3 100644
> > > > --- a/libavfilter/vf_tpad.c
> > > > +++ b/libavfilter/vf_tpad.c
> > > > @@ -148,6 +148,11 @@ static int activate(AVFilterContext *ctx)
> > > >                                frame->data, frame->linesize,
> > > >                                0, 0, frame->width, frame->height);
> > > >          } else if (s->stop_mode == 1) {
> > > > +            if (!s->cache_stop) {
> > > > +                s->pad_stop = 0;
> > > > +                ff_outlink_set_status(outlink, AVERROR_EOF, s->pts);
> > > > +                return 0;
> > > > +            }
> > > >              frame = av_frame_clone(s->cache_stop);
> > > >              if (!frame)
> > > >                  return AVERROR(ENOMEM);
> > > >
> > > >
> > > The problem with this solution is that the tpad will then not do what
> we
> > > are expecting, which is padding video track, and the output file will
> not
> > > have the desired duration.
> > > Will it not be better to just output black frame (aka stop_mode == 0) ,
> > > something like that?
> > >
> >
> > I doubt that, clone is clone, there is no point in padding stream that
> have
> > no frames at all.
> >
> >
> >
> The sample I forwarded to JB has video frames. The problem was that there
> was a re-init of the filter chain after a resolution change and after the
> re-init, there were no frames but got frames before the re-init.
> I will understand for a media file which has NEVER received a video frame
> and in this case, this is the correct solution.
>

Hmm, so you encode output with resolution change, why not use scale filter
as first filter and then no resolution ever change for rest of graph?
Adding support for resolution changes to all filters is very time consuming
task and I see no real benefit in doing that now.


>
>
> > >
> > > iff --git a/libavfilter/vf_tpad.c b/libavfilter/vf_tpad.c
> > > index e5acece1e4..5e4062e9f2 100644
> > > --- a/libavfilter/vf_tpad.c
> > > +++ b/libavfilter/vf_tpad.c
> > > @@ -140,7 +140,7 @@ static int activate(AVFilterContext *ctx)
> > >              ff_outlink_set_status(outlink, AVERROR_EOF, s->pts);
> > >              return 0;
> > >          }
> > > -        if (s->stop_mode == 0) {
> > > +        if (s->stop_mode == 0 || !s->cache_stop) {
> > >              frame = ff_get_video_buffer(outlink, outlink->w,
> > outlink->h);
> > >              if (!frame)
> > >                  return AVERROR(ENOMEM);
> > >
> > >
> > >
> > >
> > > > _______________________________________________
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> > > > ffmpeg-cvslog@ffmpeg.org
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> > > >
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> > > > ffmpeg-cvslog-request@ffmpeg.org with subject "unsubscribe".
> > > >
> > >
> > >
> > > --
> > >
> > > Thierry Foucu
> > > _______________________________________________
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> > >
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>
>
> --
>
> Thierry Foucu
> _______________________________________________
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