[Asterisk-Users] G729 vs. gsm

[Michael D Schelin]

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

Mike


Steve Underwood wrote:
> Michael D Schelin wrote:
> 
>> I have used G729 and it sounds almost as good as G711U. The problem is 
>> the way Asterisk uses it. It does not sound robotic and it's not 
>> suppose  to sound that way. Most Carriers want the calls to be in 
>> g711u so thats why I use G711u otherwise I want to save money on 
>> bandwidth. G729 on Asterisk adds latency. this could be one of your 
>> problems. Also you will not get music on hold to play well with G729.
> 
> 
> G.729 doesn't sound that bad. However, if you find it hard to tell G.729 
> from G.711, I think you should have your hearing checked. :-) It really 
> doesn't help people to assess what is right for them, if other people 
> make these exaggerated and unreasonable claims. Even the people 
> promoting G.729 give it a MOS far below G.711. You are certainly right 
> about music on hold, but even voice plus a little background noise can 
> sound bloody awful through G.729. Its performance is *very* dependant on 
> compressing just a single human voice.
> 
> Regards,
> Steve
> 
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