Re: [FFmpeg-devel] [RFC PATCH 3/3] HACK: avformat: rawenc: allow to output a raw PRFT

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

On Fri, Sep 22, 2023 at 12:06 PM Clément Péron <peron.clem@gmail.com> wrote:

> Hi Paul
>
> On Fri, 22 Sept 2023 at 11:27, Paul B Mahol <onemda@gmail.com> wrote:
> >
> > On Fri, Sep 22, 2023 at 10:38 AM Clément Péron <peron.clem@gmail.com>
> wrote:
> >
> > > Hi Andreas,
> > >
> > > On Fri, 22 Sept 2023 at 09:58, Andreas Rheinhardt
> > > <andreas.rheinhardt@outlook.com> wrote:
> > > >
> > > > Clément Péron:
> > > > > Hi Michael, Andreas,
> > > > >
> > > > > On Thu, 21 Sept 2023 at 22:50, Andreas Rheinhardt
> > > > > <andreas.rheinhardt@outlook.com> wrote:
> > > > >>
> > > > >> Michael Niedermayer:
> > > > >>> On Thu, Sep 21, 2023 at 02:17:00PM +0200, Clément Péron wrote:
> > > > >>>> Output the producer reference time to a dirty raw output.
> > > > >>>>
> > > > >>>> Signed-off-by: Clément Péron <peron.clem@gmail.com>
> > > > >>>> ---
> > > > >>>>  libavformat/rawenc.c | 122
> > > +++++++++++++++++++++++++++++++++++++++++++
> > > > >>>>  1 file changed, 122 insertions(+)
> > > > >>>
> > > > >>> this breaks fate-filter-volume and others
> > > > >>> (Segmentation fault)
> > > > >>>
> > > > >>> I can rerun it with debug symbols and provide peoper gdb output
> > > > >>> but i suspect given this has "HACK" in the title you are aware of
> > > this
> > > > >
> > > > > The "HACK" tag meaning was not supposed to be: "it's ok if it
> > > > > segfaults", but more to trigger a discussion is it possible to
> > > > > properly support an output timestamp in the raw video demux, and if
> > > > > yes how to do it :)
> > > >
> > > > If you need a timestamp for raw video, then use a proper container
> and
> > > > not raw video. In fact, this patch basically creates new formats
> > > > different from all the raw formats.
> > >
> > > Yes I agree, but I do not want to add too much overhead nor
> > > computation processing or memory copy to my pipeline just to mux and
> > > demux between ffmpeg and my python script.
> > >
> > > The idea is to have a very light structure to easily pipe it.
> > >
> > > I'm not familiar with audio/video container but it seems to me that
> > > parsing containers are not very light no?
> > >
> > >
> > Containers range from almost no processing like .y4m to complex monsters
> > like .mxf
>
> .y4m doesn't contain a timestamp either, and I don't want to use a
> complex container :),
>

I doubt storing clock time in container for each frame is correct approach.
Is this variable frame rate video?

One can always add another, trivial container with just one field having
whatever you want and with optional magic string in header.

Or can try/explore NUT container in FFmpeg.


>
> >
> > This patch is hack and approach/solution it tries is flawed.
>
> 100% agree with you that's why I prefix the patch with "HACK:",
>
> Regards,
> Clement
>
>
> >
> >
> > > Thanks,
> > > Clement
> > >
> > >
> > > >
> > > > - Andreas
> > > >
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