Re: [FFmpeg-devel] [PATCH 5/5] avformat: add sdr support

From: Hendrik Leppkes <h.leppkes@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 5/5] avformat: add sdr support
Date: Sun, 18 Jun 2023 15:30:22 +0200
Message-ID: <CA+anqdw8R05ghTC5+iHoS-H3sjxz9aG-7=Wv4Z8NMxe4Fom_=Q@mail.gmail.com> (raw)
In-Reply-To: <NYD_ij3--3-9@lynne.ee>

On Sun, Jun 18, 2023 at 2:59 PM Lynne <dev@lynne.ee> wrote:
>
> Jun 17, 2023, 20:37 by michael@niedermayer.cc:
>
> > On Sat, Jun 17, 2023 at 08:08:11PM +0200, Paul B Mahol wrote:
> > [...]
> >
> >> Which library handles compressed stuff?
> >>
> >
> > For digital stuff like DAB/DVB/...
> >
> > sdrdemux in libavformat will demodulate, do error correction then return  AVPacket
> > with H.264 / Mpeg2 video or AAC or wahetever
> > That then will get passed to libavcodec, same as with any other demuxer.
> >
> > This code is not written yet. There is just analog AM demodulation. I posted
> > this patch as soon as the first usecase worked
> >
> > usecase was "listen to random AM radio stations in ffplay" :)
> > and it can also grab all AM stations in a 10Mhz window and demodulate all
> > (that 10mhz is what my hw and usb bandwidth can do max)
> >
> > I intend to add FM demodulation, because it seems a fun thing to try to do.
> >
> > someone will need to add DAB/DVB support, I would be happy if someone else
> > comes forth to do that. If noone does ill think about if i want to do it
> > or not once FM is done and once this is in git.
> >
> > The initial reaction from some was a bit spicy, so i need to think
> > how much fun this is in FFmpeg.
> > But one thing i can say for sure, is, if i cannot use this in ffplay
> > then it makes no sense for me to put more time into it
> >
> > We could implement seeking to next/previous stations differently but
> > it seems a bit like creating extra work for everyone.
> > I mean a new API in sdrdemux then ffplay needs to support that and then
> > other players would need to support it and so on. While really the
> > seeking on a realtime input has no other use
> >
>
> I like the new functionality, but I too think that libavformat
> should just source the data from a device, and that libavfilter
> should demodulate.

And how do you deal with the prospect of future digital audio,
outputting a compressed bitstream?

- Hendrik
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