asterisk users - Feb 2006 - g729 quality at GSM bitrates

Greetings all,

I'm trying to improve the codec selection on a few of the asterisk boxes we
have to keep the g729 licences free for calls from ATAs that don't support
anything apart from g711 and g729. GSM seems to offer noticably inferior
call quality (at least when using a softphone + decent headphones), but it's
about where I want the bitrate to be.

I know there are lots of Speex options in codecs.conf - but has anyone done
some research to detemine at what bitrates and other settings Speex offers
comparable call quality with g729? Alternatively, has anyone done any
subjective comparisons between iLBC and Speex at various bitrates?

Regards,

Chris
-- 
C.M. Bagnall, Director, Minotaur I.T. Limited
This email is made from 100% recycled electrons

> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com 
> [mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of 
> Chris Bagnall
> Sent: Monday, February 20, 2006 11:43 AM
> To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
> Subject: [Asterisk-Users] g729 quality at GSM bitrates
> 
> I'm trying to improve the codec selection on a few of the 
> asterisk boxes we have to keep the g729 licences free for 
> calls from ATAs that don't support anything apart from g711 
> and g729. GSM seems to offer noticably inferior call quality 
> (at least when using a softphone + decent headphones), but 
> it's about where I want the bitrate to be.
To my ear, ILBC sounds much better than GSM. It's slightly more
efficient, and more tolerant of things like packet loss. Some folks,
hate the sound of ILBC encoded calls. <shrug>

Your other choice would be G.726/32. * supports it, as do many ATA's and
softphones. It's a bit fatter, but sounds MUCH better than GSM.