[asterisk-dev] [svn-commits] jrose: branch 1.8 r371337 - /branches/1.8/channels/chan_sip.c

[Jonathan Rose]

Olle wrote:
> From: "Olle E. Johansson" <oej at edvina.net>
> To: "Asterisk Developers Mailing List" <asterisk-dev at lists.digium.com>
> Sent: Thursday, August 16, 2012 11:06:35 AM
> Subject: Re: [asterisk-dev] [svn-commits] jrose: branch 1.8 r371337 -	/branches/1.8/channels/chan_sip.c
> 
> 
> 16 aug 2012 kl. 17:46 skrev SVN commits to the Digium repositories:
> 
> > This patch
> > just queues a source change control frame if the dialog is using
> > directmedia when we find sdp for an ACK.
> 
> Can we document in which occasions we should send such a control
> frame
> and what happens if we do?
> 
> Are these in any way releated to the SDP ssrc?
> 
> /O

I might just not be aware of it, but I don't think we currently
document this sort of information (specifically referring to
cases when we would use a specific control frame) for any other
type of control frame (of which there are currently more than
30). There is a short description of every control frame type
in frame.h, and for SRCCHANGE, it says:

/*!< Media source has changed and requires a new RTP SSRC */

I don't know what a broad effort to document when any given
control frame is necessary would entail at the moment. I
imagine it would be rather large since there are tons of
control frames and many more places where they can be
queued.

Yes, this is related to SDP ssrc. With Directmedia, Asterisk needs
to send reinvites indicating new addresses for phones to send
RTP to the connected endpoints in a dialog. Asterisk gets these
addresses from the SDP in the relevant message which triggers
directmedia.