From: "Cullen Jennings (fluffy)" <fluffy@cisco.com>
To: Eric Rescorla <ekr@rtfm.com>
Thread-Topic: [MMUSIC] SDP work needed for WebRTC stuff
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Date: Sun, 9 Dec 2012 00:19:46 +0000
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Cc: "<rtcweb@ietf.org>" <rtcweb@ietf.org>, mmusic WG <mmusic@ietf.org>,
 "<public-webrtc@w3.org>" <public-webrtc@w3.org>
Subject: Re: [MMUSIC] SDP work needed for WebRTC stuff
Precedence: list

On Dec 8, 2012, at 4:21 PM, Eric Rescorla <ekr@rtfm.com> wrote:

> +rtcweb
>=20
> On Sat, Dec 8, 2012 at 2:41 PM, Cullen Jennings (fluffy) <fluffy@cisco.co=
m> wrote:
>=20
> I was looking over everything that needs to be completed to finish a fist=
 cut of the WebRTC related work. There are a handful of big SDP problems th=
at are currently blocking some of the WebRTC work and I'd like to figure ou=
t how to make some progress on them.
>=20
> Let me loosely characterize them as
>=20
> 1) If we have several video streams, how do theses map up to 1 or more m =
lines.
>=20
> 2) if we are doing port multiplexing, what does the SDP look like (the bu=
ndle problem)
>=20
> 3) How do we map the RTCWeb track and stream label concepts to identifier=
s in SDP
>=20
> 3) SDP for application running over SCTP/DTLS
>=20
> I don't want to speak for all the various chairs but I am under the impre=
ssion that most of chairs of related groups in W3C and IETF believe these a=
re issues that need to be resolved primarily in the MMUSIC WG and that they=
 impact both WebRTC and CLUE as well as the general long term use of SDP in=
 SIP and other protocols.
>=20
> I'd like to get some discussion going on how we can make some progress on=
 these. I don't think we are going to solve these in 20 minutes of discussi=
on at an IETF meeting so I think we probably need some interim (virtual or =
face to face) to sort this out.
>=20
> Thoughts?
>=20
> Wow, I'm totally confused here.
>=20
> I had assumed that the SDP-related issues were going to be the main
> topics at the WebRTC/RTCWEB interim in January. Is that not the case?

So far the interim was only talking about being a WebRTC & RTCWeb so this S=
DP stuff would be out of scope. Perhaps it would be better to have some of =
the time for mmusic topics?=20


>=20
> IMO the lack of clarity around how to encode various media
> configurations into SDP is the major thing blocking progress here. In
> particular, Firefox has opted not to implement multiplexing of media
> streams over the same transport flow (whether of the bundle or
> multiple m-line variety) until the SDP for it is well-defined. The
> same thing applies to the question of how to map multiple m-lines to
> incoming MediaStreams/Tracks.
>=20
> We really need to cover these issues in the interim.
>=20
> -Ekr
>=20
>=20