[FFmpeg-devel] [PATCH] libavformat/prompeg.c: Add parameters to control FEC ports.

[Kieran Kunhya]

On Fri, 13 Dec 2024, 16:38 Romain Beauxis, <romain.beauxis at gmail.com> wrote:

> Le ven. 13 déc. 2024 à 16:42, Romain Beauxis
> <romain.beauxis at gmail.com> a écrit :
> >
> > This patch adds parameters to pick specific ports for the two FEC error-
> > correction streams associated with a Pro-MPEG CoP #3-R2 FEC streams.
> >
> > Radio France is currently interested in using this technology to do
> > error-correction on some of their stream. In this context, they may not
> > have full control over their available UDP ports and would like to be
> able to
> > pick any two ports for these streams.
> >
> > The specifications for this protocol is available online:
> https://www.yumpu.com/en/document/read/8808550/pro-mpeg-code-of-practice-3-release-2-pro-mpeg-forum
> >
> > In section 5.2, page 14, port assignments for the FEC streams are under
> > "shall" thus the changes in this patch should still be valid w.r.t. the
> > specs.
>
> A bit surprised, as I re-read the specs now, to learn that "shall" is
> to be interpreted as a mandatory requirement while, usually, "must" is
> used. My understanding of the English language has failed me once
> more!
>
> Still, I believe that this patch should be useful (shall, if
> considering the use-case I came from!).
>
>
What FEC receivers allow custom port selection? All the ones I've seen
expect +2 and +4. If they are internally mapping to +2 and +4, I am not
sure it's a good idea that FFmpeg features are added to work around
someone's firewall limitation.

Kieran