[Asterisk-Users] G729 vs. gsm

[Steve Underwood]

Michael D Schelin wrote:

> Steve, you should really test the Codec and have G729 running as a 
> pure IP to IP call you can not hear the difference on good networks! 

Well, it does to anyone without hearing damage. It sounds very obviously 
different.

> Please do not get me wrong that G711u sounds better through the PSTN.  
> Thats a given! You can't convert G729 up and down to G711 and expect 
> the sound quality to be there. I'm a carrier and have tested G711 and 
> G729 and have found that they both sound great through dedicated hardware.

This is meaningless drivel.

> Asterisk's colors the G729 a little. Also my

The only time when Asterisk colours G.729 is when there is packet loss. 
Asterisk isn't handling that well.

> hearing is fine. Please do not put down the comments of others in this 
> forum. I'm stating my comments from my real world trials and this is 
> not bad information.

Since it doesn't correlate with the impression of even the developers of 
G.729, it *is* bad information. Realistic people know G.729 will be 
worse. What they need is meaningful guidance as to just how much.

> The man must compare codecs on his own and see what works for him. For 
> me we've stuck with G711u because it's best through the PSTN. If I was 
> running a pure IP to IP system I would use G729, Iblc, or GSM.

In a sane world pure IP to IP systems would't use G.711, G,729, iLBC, or 
GSM. They would be usign a wideband codec, as Skype does. Look at the 
favourable impression people have of that.

Next time, its probably better to argue with someone who hasn't spent 
time in speech codec development. We tend to have a clue what we are 
talking about. :-)

Regards,
Steve