[LAU] Streaming radio and calls from listeners

[Len Ovens]

On Sun, 22 Jun 2014, Louigi Verona wrote:

> For more than a year I am producing a skeptic-oriented podcast. So far it's
> been an offline venture. We have a nice audio mixer from Yamaha that we are
> recording as one track into Qtractor.

So, it sounds like you have been doing all your mixing outside the 
computer then. (just checking)
> 
> However, I am thinking towards live streaming and accepting calls from
> listeners. Is this realistic with Linux? If yes - can anyone suggest how?

Try reading about http://idjc.sourceforge.net/ in particular 
http://idjc.sourceforge.net/tutorials_voip.html Though I have also seen 
setups with pulse->jack... I have not tried pulse->jack with my new 
computer but it required too much CPU on the old single core P4.
(by the way the idjc here is _not_ Idaho Department of Juvenile 
Corrections)

Remote content providing that I know has worked:
-teamspeak (oss sound on a second computer <for enough cpu> mixed in an 
external mixer)
-mumble
-others as mentioned

Skype likes to play with levels of the sound card... owned by MS so it 
likes to be in control...  However, lots of people have a skype account, 
but only the free part so they can not call a number or a named voip 
account. They also can not accept a call from non-skype voip unless you 
have a paying account.

With regard to content filtering of live calls, not just from a legal 
perspective, but also from what you want your listeners to hear. The 
standard method used here when I was in the business years ago was to 
delay the whole studio audio about 7 seconds and provide a cut button that 
shut off the audio after the delay. It gave some interesting echo effects 
when the call in had their radio turned up too high  :)  The idjc DSP 
button could be used for this if you were using that SW... most effects 
have a bypass button too.

One thing I would like to try for remote content is to use netjack... Your 
master server has to be inet visible though. Which brings a question to 
mind... can a jackd server with a net backend also be a netjack master? I 
guess the real question is if a netjack master can be tied to a particular 
network interface. The idea being that the studio machine with the audio 
card is master on the local net. The webserver is a slave on the local 
net, but a master to the internet. The other way would be to put a 
soundcard in the webserver for timing only and make it master of all. Then 
use zita-aj for the real audio card. The problem with the second method is 
that the local net would have compressed audio and all machines using 
netjack would have the added overhead of the codec.

--
Len Ovens
www.ovenwerks.net