[TriLUG] ANy interest in VoIP on Linux? How about AoIP?

Jim Ray jim at neuse.net
Sun Apr 13 20:10:33 EDT 2003


Even wired music with standard Ethernet would be better than
conventional analog.  The trick is getting a Linux box to act as a
server and mediate traffic.  For example, send guitar channel to left
main front of house, and send keyboard channel to right main front of
house.

The real kicker is using a couple of Fourier transforms to calculate the
difference between the actual and desired front of house signals and to
consequently perform equalization.

So, we're not really talking about wireless alone.  In the digital
domain, one could very easily have data specific to bands and venues for
a quick double click on this and play scenario.  I can't tell you how
many hours I've spent tweaking 31 band graphic equalizers with the help
of pink noise and a spectrum analyzer to set frequency response.

Now, that digital stuff being said, I also proudly profess to be an
analog purist with my electric guitar and normally have nothing in the
signal path other than metal cable, vacuum tubes and polypropylene
capacitors.

AoIP with its 20kHz BW has different rules than VoIP with its 3.4kHz BW.
Take 24 channels * 20kHz * 2 for the Nyquist sampling theorem.  Your up
there in frequency.  Has Linux got the umph to process the signals and
replace a 24 channel mixing board?

I figure the same code that makes the VoIP PBX do a conference call
could be re-used for an AoIP system.

> -----Original Message-----
> From: Mark Shuford [mailto:davemarcus at pobox.com] 
> Sent: Sunday, April 13, 2003 3:48 PM
> To: trilug at trilug.org
> Subject: Re: [TriLUG] ANy interest in VoIP on Linux? How about AoIP?
> 
> 
> On Sun, 13 Apr 2003 11:35:36 -0400
> "Jim Ray" <jim at neuse.net> wrote:
> 
> > As long as the bandwidth is 20kHz instead of 3.4 kHz, 
> emphatic "yes."
> > 
> 
> Well, I have to say that 20k bandwidth is quite a bit more 
> than 'voice'! The 3k is all the phone company gives you, after all.
> 
> And VoIP for wireless musical sounds like overkill to me. As 
> a matter of fact packet switched for wireless musical doesn't 
> recommend itself to me at first or second glance. Of course, 
> I'm interested in discussion here.
> 
> And for that matter I'm not completely sold on digital audio 
> for the highest quality by any means.
> 
> And I missed the April TriLUG meeting on Internet Radio 
> Linking Project (IRLP) so that might have been a good place to start.
> 
> 
> -- 
> Mark Shuford
> 
> Now I know what a statesman is; he's a dead politician. We 
> need more statesmen.
> 					--Bob Edwards
> 
> Visit me at: http://www.krazeemark.com  (Got the blog up...) 



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