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

[Steve Totaro]

On Wed, May 21, 2008 at 8:11 AM, Steve Totaro
<stotaro at totarotechnologies.com> wrote:
> 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
>

Second thought to consider, I have seen FXO modules go bad where they
generate noise but do not completely die.  Can you route the call to
different FXO modules and see if it makes a difference?

Thanks,
Steve Totaro