[Asterisk-Users] Where can i get the g.723 codec?

[Steve Underwood]

Andrew Gillham wrote:

> Steve Underwood wrote:
>
>> Hi Thomas,
>>
>> Unless you have a *very* specific need to use G.723.1 for 
>> compatibility with someone else, forget it. It is pretty much an 
>> obsolete product. Licencing is also a pain, as there is not patent 
>> pool for it. G.729 is expensive to licence, but at least it is 
>> relatively strightforward. If you think you will save some bits using 
>> G.723.1 instead of G.729, think again. The saving is minute, because 
>> of the huge overheads IP imposes.
>>
>> Regards,
>> Steve
>
>
> I was measuring about 32-36 Kbit/s for a G.729 call, and around 
> 20-22Kbit/s for G.723.
> This is at the DSL router, so it includes all of the overhead.
>
> If you're on a dialup modem, that can make or break the call.
>
> -Andrew

What you are seeing their is not the codec at work, but the huge 
overhead of RTP. G.723.1 uses 30ms blocks. G.729 normally uses 20ms 
blocks. They are both usually sent with one block in each RTP packet. If 
you don't mind a little more latency, put two G.729 blocks into each RTP 
packet (I'm not sure if Asterisk supports that, but many things do). 
Then you have a packet every 40ms, a lower bit rate than G.723.1 and 
better voice quality.

Regards,
Steve