[Icecast] Basic questions

[Petr Pisar]

V Sun, Apr 25, 2021 at 08:43:26PM +0100, Ken Gillett napsal(a):
> What I want to do is broadcast on my LAN (i.e. around the house) some
> satellite radio streams, by which I mean stations that broadcast on FreeSat
> (here in the UK). FTA and unencrypted. I have a satellite tuner card in the
> mediaserver and I’d like to be able to access those radio streams (about
> a dozen, max.) and make them available to any IP radio receiver (that should
> be able to use Icecast streams).
> 
> The tuner card and Icecast would be on the same server and with no clients
> listening, there would be no output onto the LAN and if those stations were
> still ’streaming’ internally, that’s probably not an issue.
> 
> However, any suggestions as to how I could connect the Sat tuner output to
> Icecast input? The Sat tuner is standards compliant (I believe, V4l?), but
> I could run minisatip, so those stations would be accessible as standard
> SAT>IP streams. But again, any suggestions how to make this connection
> between the Sat tuner and Icecast?
> 
I have almost no experience with V4L2. So I cannot help you.

Here
<https://unix.stackexchange.com/questions/113668/multiple-fm-radio-streams-from-dev-radio-via-v4l2-ices2-and-icecast>
somebody reported that he uses IceS program to read sound from an ALSA device
which is in real a virtual ALSA devices provided by a PulseAudio deamon which
feeds the ALSA output with a PCM sound read from a /dev/radio0 character
device provides by his V4L2 tunner. Then IceS compresses the PCM audio into
a format of you choice (e.g. Vorbis) and forwards the compressed audio to
an Icecast server.

I have some doubts whether this is the best option. In my opinion
a satellite broadcasting uses an MPEG TS stream. Thus it should be possible
just to repack the MPEG format from a MPEG TS container into ICY protocol
without transcoding the audio. That should preserve quality of the sound and
conserve a CPU power. If it is possible, then I bet somebody has already
written such software. E.g. ffmpeg can be requested not to recompress with
a "copy" codec. And here
<https://gist.github.com/keiya/c8a5cbd4fe2594ddbb3390d9cf7dcac9> is ffmpeg
used as a source for Icecast.

-- Petr
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