[Asterisk-Users] G.729? Worth it?

[Andrew Kohlsmith]

On January 19, 2005 12:23 pm, Paul Fielding wrote:
> I think you might want to clarify that Best audio quality is in relation to
> other highly compressed codecs.  Certainly my (albeit limited) experience
> is that g711 is much more clear than g729.   Compared against gsm, for
> example, however, the audio quality is quite good....

heh -- everyone keeps bashing on GSM but out of the low bitrate codecs I've 
tried (G711, GSM, iLBC) GSM is king (G711 is the absolute upper bound of my 
"low bitrate") 

I want to like iLBC, I really do...  but every single time I've tried it I've 
had complaints of crackling and all around poor audio.  Trunked or not 
trunked, trunkfreq=30 and default trunkfreq (20) -- it's always the same.  
Flip back to GSM and everyone's happy.

The servers aren't chintzy, either.  Xeon 2.8 with TE405P to Bell Canada PRI, 
dedicated IAX2 link to your choice of P3/700, P3/800 or another Xeon 2.8.  
stock Linux 2.4 kernel, no funky compile options for zaptel or asterisk...

It's strange...  I'm keen on iLBC because of the excellent PLC capabilties 
that will come around with the new IAX2 jitter buffer, but I just can't get 
it to sound good.

Any ideas for additional testing would be great -- I'm not afraid of packet 
captures or code hacking but I'm not sure where to begin at this point.  My 
links are solid (no packet loss, low jitter, you name it) and as I said... 
G711, GSM, ulaw... these all sound great.  It's just iLBC.

-A.