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

[Olle E. Johansson]

16 aug 2012 kl. 18:35 skrev 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).
Which I think should change. :-)
That we have no documentation today is no excuse not to write it, is it?

We do update the SSRC too often in a call and need to agree on when this should be used.
I haven't been able to track it and the documentation of these control frames
was missing, so I think they've been misused for any change related to
media.

> 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.


I guess I know what Directmedia means... But thanks for the 
explanation.

/O