Re: [MMUSIC] Draft on source-specific SDP attributes: draft-lennox-mmusic-sdp-source-attributes-00

Colin Perkins <csp@csperkins.org> Sun, 18 March 2007 10:21 UTC

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From: Colin Perkins <csp@csperkins.org>
Subject: Re: [MMUSIC] Draft on source-specific SDP attributes: draft-lennox-mmusic-sdp-source-attributes-00
Date: Sun, 18 Mar 2007 11:21:05 +0100
To: Jonathan Lennox <jonathan@layeredmedia.com>
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Cc: mmusic WG <mmusic@ietf.org>, Joerg Ott <jo@netlab.tkk.fi>, Thomas Schierl <schierl@hhi.fhg.de>
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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.

Can you comment on the interactions between parameters specified in  
"a=fmtp:" lines and those specified in "a=ssrc: fmtp" lines? There  
would seem to be the potential for significant confusion here, yet  
the draft goes into relatively little detail.

Also, what are the interactions between congestion control and the  
media source bandwidth attribute? The are already problems with  
reconciling this with media level "b=" attributes: will these get  
worse with media source bandwidth attributes?

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



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