[asterisk-users] G.722 problems with IAX

[Armin Schindler]

On Thu, 3 Sep 2009, Tilghman Lesher wrote:
> On Thursday 03 September 2009 02:47:05 Armin Schindler wrote:
>> Hello,
>>
>> I try to move our asterisk installation (3 Asterisk servers in different
>> offices connected using IAX and a lot of SIP phones, as well as ISDN
>> connections using CAPI) to use G.722 instead of G.711.
>>
>> Asterisk 1.4.25.1 is used with the G.722 patch (the fixed one, which solves
>> the gain problem).
>> So SIP-to-SIP and to ISDN there is no problem. G.722 itself works and
>> transconding to G.711 for ISDN also works good.
>> But when I make a connection through IAX to another asterisk (having
>> allow=g722 to really use G.722 in IAX) the voice is 'broken'.
>>
>> I also work on G.722 for twinklephone and encountered a special thing about
>> G.722: It has a sample rate of 16000, but it announced as 8000 in SDP.
>> Since I have similar problem with my G.722-twinkle implementation, it looks
>> like the RTP and/or jitterbuffer code has a problem with that.
>> Did I miss something here or is this really a bug?
>
> You missed that the IETF has a typo in the specification, stating that G.722
> is to be stated as 8000, even though it's 16000.  This will remain, due to
> backwards compatibility concerns.  Please see RFC 3551, section 4.5.2.
> http://www.apps.ietf.org/rfc/rfc3551.html#sec-4.5.2

No, I didn't miss that. See my text.
I mentioned this because I think this might be the reason of the problem and
the incorrect handling in jitterbuffer, if it is the jitterbuffer. It is 
just a guess, since everything else seems to work good.
The question is why does G.722 via IAX has problems.
Is anyone using it and can say it works in his setup?

Armin