Subject: [AVT][MMUSIC] draft-lennox-mmusic-sdp-source-attributes-00 and RTCP SDES

From: Colin Perkins <[email-masked]>
Date: Sun, 18 Mar 2007 11:11:24 +0100

On 27 Feb 2007, at 20:03, Jonathan Lennox wrote:
> Joerg Ott, Thomas Schierl, and I have written an Internet-Draft on  
> source-specific SDP attributes, draft-lennox-mmusic-sdp-source- 
> attributes-00, now available from the I-D repository.
>
> The draft allows individual RTP sources to be described in SDP  
> session descriptions, generalizing the mechanism used by the draft  
> on RTCP extensions for single-source multicast (draft-ietf-avt- 
> rtcpssm).  It was also originally motivated by the desire to  
> support ssrc-multiplexing of H.264 SVC, as originally used by draft- 
> wenger-avt-rtp-svc-02 and draft-schierl-mmusic-layered-codec-01,  
> though the latest revisions of those drafts have dropped support  
> for ssrc-multiplexing for other reasons.
>
> Comments are welcome.
>
> I'm sending this announcement to the AVT group as well as MMUSIC,  
> as the draft's mechanisms have non-trivial interactions with RTP  
> collision detection.   Please direct followups to only one of the  
> working group mailing lists, depending on the topic being discussed.

[Sent to both lists, since this is a cross-group issue]

There is potential overlap between the media source attributes  
defined in this draft and the information conveyed in RTCP SDES  
packets. We should be clear on how these two mechanisms relate, what  
types of information should be signalled in SDP, and what types  
should be conveyed via RTCP SDES packets.

In the current draft, for example, the media source attributes for  
conveying a textual description of the source, and the source  
language, would seem to fit the sort of information usually sent in  
RTCP SDES items.

-- 
Colin Perkins
http://csperkins.org/

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