[FFmpeg-devel] [PATCH 0/7] RFC: complete rework of s337m support

[Kieran Kunhya]

On Thu, 12 Dec 2024, 13:07 Nicolas Gaullier, <nicolas.gaullier at cji.paris>
wrote:

> >De : ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> de la part de Anton
> Khirnov <anton at khirnov.net>
> >Envoyé : jeudi 12 décembre 2024 09:36
>  >
> >I am not intimately familiar with these formats and their mutual
> >relationship, so these problems you refer to are not clear to me.
> >What I am familiar with is our APIs, and from that position I can say
> >this:
> >1) Nested decoders are huge red flag. For one thing, they are very
> >   tricky to implement properly - almost every one I've touched had
> >   subtle bugs that were fixed by moving to a non-nested design.
> >
> >   But even more importantly it's a sign that there is something fishy
> >   going on, and maybe the thing you're dealing with is not really a
> >   codec and should be handled in some other layer. It's more of a rule
> >   of thumb than a hard rule, but it does mean that nested decoders need
> >   a strong argument justifying them.
> >2) In-decoder resampling is another big red flag. We have consciously
> >   moved a long time ago towards decoders exporting their native format
> >   and (whenever feasible) not doing any format conversion internally.
> >   Opus is a special case in that resampling there is required by the
> >   spec to combine CELT with SILK.
> >
> >   Again, you could claim that resampling is also fundamentally required
> >   in your case, but then you should have a strong supporting argument.
> >
>
> Thank you Anton for taking time to precise your mind.
> I understand your point.
> Unfortunately, I don't know how to move on.
> I think I will shelve this work until someone has an idea how to deal with
> it.
>

It is required in his patchset because you could have PCM at 48khz, then
Dolby E at some other sample rate that's expected to be output at 48khz.
Any of these can change on the fly but the base rate is 48khz (in order to
have a simple frame cadence with NTSC video)

Kieran

>