[asterisk-users] speex, ilbc and g729 codecs, GSM with IAX

[Steve Totaro]

On Wed, May 21, 2008 at 7:28 AM, bilal ghayyad <bilmar_gh at yahoo.com> wrote:
> Dears;
>
> I do not know if any had experience in using speex or
> ilbc with IAX and got good results, because I am
> facing a problem with GSM.
>
> I am facing a noise problem when I am using GSM with
> IAX trunk as following:
>
> IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
> using GSM codec ---> Remote Asterisk Box ---> Digium
> Card (FXO) to terminate the call to the destination
>
> While no noise happen if that senario is happening:
>
> IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
> using GSM codec ---> Remote Asterisk Box ---> Digium
> Card (FXS) to an extension
>
> I tried to use GSM with IAX trunk, and actually I got
> a problem that: when I am using IP Phone (Polycom 320,
> with G711 codec) and placed a call, that call will go
> via the IAX trunk to the remote Asterisk Box, then
> using the Digium TDM22B card to terminate the call via
> the PSTN analoge lines, there is a noise coming with
> the voice! This noise does not appear if we do not use
> the "IAX trunk and if the call is not going to be
> terminated via the Digium Card (FXO) on the remote
> Asterisk Box (if we use IAX trunk and we call an
> extension (FXS) on a remote Asterisk but not the PSTN
> and the FXO on the remote Asterisk, then no noise
> appear).
>
> So the noise happen only in that senario:
>
> IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
> using GSM codec ---> Remote Asterisk Box ---> Digium
> Card (FXO) to terminate the call to the destination
>
> While no noise happen if that senario is happening:
>
> IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
> using GSM codec ---> Remote Asterisk Box ---> Digium
> Card (FXS) to an extension
>
> I do not know if it is a matter of the GSM codec, or
> if it is related to the digium card that it is the old
> model.
>
> But any one can advise if speex or ilbc will give
> better performance than GSM with IAX trunk?
>
> Any advise?
> Regards
> Bilal
>
> --------------------
> bilal ghayyad wrote:
>> Hi List;
>>
>> Anyone tried to use speex, ilbc and g729 and come
> back
>> with a preferred one in the quality?
>>
>> Regards
>> Bilal
>>
>>
>>
>
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> Depends on what you're using it for.  We've had
> excellent luck with
>  iLBC
> for voice quality and g729 as well. Speex is better
> than GSM, but not
> spectacularly.
>
> The problem with all of them of course, is
> transcoding. They have less
> of a bandwidth footprint for acceptable quality, but
> more of a
>  processor
> footprint.
>
> N.
>

I would check the "old" digium card first.  Check interrupts and all.
Describe the "noise".

I am inclined to to think it is a hardware issue since it only
exhibits itself when using the Digium card.

Thanks,
Steve Totaro