[arm-allstar] THANKS - How do I modify iax.conf?

[Doug Crompton]

Pete,

 You are right the codecs are defined in iax.conf.  This file is located in
/etc/asterisk. If you log into your system via ssh or putty you can select
item 9 on the menu to start the bash shell. Once there do:

cd /etc/asterisk      then
nano iax.conf

You will see in the [general] stanza the following:

disallow=all

allow=g726aal2

allow=ilbc
allow=ulaw

allow=gsm

This tells Allstar to use the g726 codec first, followed by ilbc, ulaw, and
gsm.

You can reorder the priority or completely eliminate a codec by commenting
it out (placing a semicolon at the beginning of the line).

You also need to do the same thing in the [radio] stanza a little further
down.

You did not say what you wanted to change but be careful as limiting the
codecs could stop you from being able to connect to certain nodes and them
to you. Of course this is not permanent and can be remedied by again
changing these stanzas.

g726 is probably the most used codec. It has good audio quality and uses a
reasonable amount of bandwidth

ILBC uses about 1/3 the bandwidth of G726 but still retains excellent
quality. This is often used in portable operation where cell data is being
paid for or on limited bandwidth circuits.

gsm is rarely used. It is "echolink" quality audio but also less bandwidth,
about the same as ILBC

ulaw is the best audio quality but many could not tell the difference
between it and g726. It also uses the most bandwidth. While some like to
use it especially for repeater links it would be wasteful of bandwidth for
most applications.

Keep in mind that mixing a lot of different codecs results in transcoding
(converting from one format to the other) and uses more processor power.
While it usually does not happen ideally all users to a multi-user hub
would be using the same codec. This can be forced if the hub only allows a
specific codec.

You can see what codec is being used by users who are connecting to your
system.

Select the item 11 - run Asterisk client in the menu

at the prompt type -

iax2 show channels

I hope this helps.


*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*


On Thu, Aug 17, 2017 at 5:34 PM, "Peter Adams via arm-allstar" <
arm-allstar at hamvoip.org> wrote:

> First I want to thank Doug and crew for the great work getting their Pi
> image running on the Pi / Allstar. I've attempted to get Allstar running on
> a PC with other images a while ago and ran into problems that stopped me
> cold. Using Doug's image on the Pi allowed me to get up and on the air
> pretty easily. I'm Linux newbie so the less Linux the better. That said,
> I'm
> pretty comfortable poking around so I can learn how things work and also to
> allow me to make the most of Allstar and Asterisk.
>
>
>
> Yeah, I know, a major newb question but...
>
>
>
> To that end, I want to access and change codecs. I understand that they
> live
> in iax.conf
>
> Long story short , despite my research I can't find out how to do this.
>
> How do I get to this file and how do I modify that stanza.
>
>
>
> Thanks
>
>
>
> Pete Adams
>
> K4PRA
>
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>
>