[Freeswitch-users] Sofia late-negotiation onre-INVITE(codec-modification)

[Visciano Giovanni]

I used to say to my boss:
... it's not a bug it's a feature! I'm kidding :)

By the way, even in this "design choice", al least the first test scenario is a bug
(described in the first half on the Jira BUG):
http://pastebin.freeswitch.org/17906

Moreover this "by design" behavior create some problem not only for
transcoding issue but also for fax upspeed codec modification (no T38).

Years ago, when hardware resources where poor, I had a lot of discussions with
my colleagues to avoid the allocation of transcoding resources on our softswitch
and we always ended up to use a transcoding resource if and only if it's really needed,
if the endpoints can speak the same language let them do all the stuff. I know
easy to say but ...

Back to FS, what I think is we miss an endpoint independent codec negotiation signaling.
I mean something like we have in the call setup phase via "absolute_codec_string"
/ "ep_codec_string" / SWITCH_ORIGINATOR_CODEC_VARIABLE.

As I'm playing/prototyping a new endpoint module I used these channel variable to
successfully interworking with SIP endpoint gateway in codec passthrough...
but now that the test-suite is going over the SIP basic call codec modification I found
that "by design problem".

In the (working) spare time I'm trying to write a patch to extend the core interworking
opening the way I suggested few lines over. As I'm very new to FS, for now it's a very
embryonal and poor implementation in my opinion, but enough for the endpoint module
prototype evaluation.
I hope to give that back to you if I can find more time to move the patch to a presentable level.

Giovanni

-----Original Message-----
From: freeswitch-users-bounces at lists.freeswitch.org on behalf of Brian West
Sent: Wed 12/21/2011 6:30 PM
To: FreeSWITCH Users Help
Subject: Re: [Freeswitch-users] Sofia late-negotiation onre-INVITE(codec-modification)
 
I don't think this is a bug... I think its by design.

/b

On Dec 21, 2011, at 11:26 AM, Visciano Giovanni wrote:

> I've opened a BUG.
> http://jira.freeswitch.org/browse/FS-3739
> 
> I don't know what's you FS configuration.
> What I know is:
> - SIP "media proxy mode" is OK.
> - re-INVITE for codec modification to image T.38 (t38-passthrough) is OK in all SIP "media mode".
> 
> The "late_negotiation" + "inherit_codec" trick to avoid transcoding in a Back2Back
> (that is no media proxy) configuration works only for the very first call setup SDP offer/answer.
> http://wiki.freeswitch.org/wiki/Codec_negotiation
> 
> Once the call is established, further codec modification via re-INVITE are usually closed on
> each leg (except for t38) and this can led to transcoding (and obvious errors if you can't or don't want
> to transcode).
> 
> Hope this helps you find out your problem.
> 
> Giovanni

-- 
Brian West 
FreeSWITCH Solutions, LLC
Phone: +1 (918) 420-9266 
Fax:   +1 (918) 420-9267
brian at freeswitch.org
http://www.freeswitch.org



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