Icecast - Apr 2021 - Basic questions

Thank you for your response. Most helpful.

Sounds like the ?relay? option is perfect for my needs, however I?d like to ask
further about the other question.

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?


Ken  G i l l e t t

_/_/_/_/_/_/_/_/


> On 25 Apr 2021, at 19:13, Petr Pisar <petr.pisar at atlas.cz> wrote:
> 
> V Sun, Apr 25, 2021 at 04:24:28PM +0100, Ken Gillett napsal(a):
>> ? Does icecast use unicast and/or multicast?
>> 
>> ? If multicasting, do all listeners simply latch on to the same
multicast
>> stream?
>> 
>> ? If no local clients listening, does that mean nothing is being
broadcast
>> onto the local network?
>> 
> Icecast implements ICY protocol (defined by Shoutcast software) which is
> similar to HTTP, hence TCP, hence unicast.
> 
>> ? If relaying a stream from another server and unicasting locally, am
>> I right in thinking that it pulls a single stream from that external
server,
>> but can then re-broadcast that to multiple local listener clients?
>> 
> Yes.
> 
>> ? If set up to relay as above, but there no local clients actually
>> listening, will icecast still be pulling the stream from that external
>> server over the connecting network (broadband link in my use case)?
>> 
> No. When relaying another ICY stream (e.g. from another icecast server),
> icecast disconnects from the external server.
> 
> But do not get confused with connections from "sources" (in
constrast to
> relaying). Sources are origins of a stream (a sound from micropone or local
> files encoded into a stream, e.g. with ices tool) and they manage the
> connection to icecast. Sources initiate and close the connecion. Thus they
> usually remain streaming even if no ICY client is connected to the icecast
> server.
> 
> -- Petr
> _______________________________________________
> Icecast mailing list
> Icecast at xiph.org
> http://lists.xiph.org/mailman/listinfo/icecast

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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