[asterisk-dev] [Video / SIP] Codec negotiation passthrough ?

[Kevin P. Fleming]

On 09/02/2010 07:09 AM, Nicolas Bourbaki wrote:

> I've got a litlle problem : Asterisk rewrite every SDP in codec
> negociation, even for video. I would have liked that I don't loose any
> information for video, as some are constructor specific.

Asterisk does not 'rewrite' SDP; it's not a proxy. Asterisk is a B2BUA,
and as such when it creates an outbound channel, that channel is totally
distinct from (but related to) the inbound channel. The SDP on the
outbound channel is created by Asterisk based on the configuration of
the SIP endpoint that is being called, with a little bit of input from
the incoming channel's configuration.

The issue you are trying to address has been known for quite a while,
and there was a 'videocaps' branch/patch for Asterisk 1.4 that addressed
it in a fairly simple way for video streams specifically. There have
been many discussions about how to do this the right way, and those are
still ongoing. Whatever solution is created is not going to involve
directly copying SDP information from one channel to another, because
that doesn't support Asterisk's nature as a multiprotocol telephony
platform.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
skype: kpfleming | jabber: kfleming at digium.com
Check us out at www.digium.com & www.asterisk.org