[FFmpeg-devel] [PATCH 4/4] avformat/mxfenc: add some missing content package rates

[Tomas Härdin]

ons 2020-03-04 klockan 17:48 +0100 skrev Carl Eugen Hoyos:
> Am Mi., 4. März 2020 um 17:29 Uhr schrieb Tomas Härdin <
> tjoppen at acc.umu.se>:
> > ons 2020-03-04 klockan 11:31 +0100 skrev Carl Eugen Hoyos:
> > > Am Di., 3. März 2020 um 02:18 Uhr schrieb Marton Balint <
> > > cus at passwd.hu>:
> > > 
> > > > 2) support all frame rates and write 0 (undefined) as the
> > > > package rate
> > > > for frame rates which cannot be exactly represented
> > > 
> > > Why not?
> > > 
> > > Allow me to repeat: Professional archivists recommend using mxf.
> > > How
> > > do they store digitized content from (old) low-fps film?
> > 
> > We can worry about that when archivists open tickets on trac.
> 
> A ticket was actually opened asking for more frame rates (just as
> a ticket was opened earlier because of a limitation in aspect
> ratios),

Which one? #8523?

> I wonder why mxf is the only (?) libavformat muxer that tells the
> user which frame rates (in the past: which aspect ratios) to use.
> It is very hard to believe that the reason is that mxf does not allow
> other frame rates (I have to listen once a year to a presentation
> explaining how versatile mxf is compared to all other multimedia
> containers).
> 
> Just print a warning when you feel that the chosen framerate will
> not ensure maximum compatibility.

If the output can be guaranteed to be correct, sure. If not then no. We
should not output files which we can't verify to be correct, especially
when it comes to MXF. The ecosystem is enough of a mess as it is. It is
pointless to output files with mxfenc that can only be consumed by
mxfdec. To be useful the output must be possible to exchange with other
MXF decoders.

/Tomas