Re: [MMUSIC] Simulcast: Short timelines, draft impending
Suhas Nandakumar <suhasietf@gmail.com> Fri, 02 October 2015 22:48 UTC
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Date: Fri, 02 Oct 2015 15:48:06 -0700
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From: Suhas Nandakumar <suhasietf@gmail.com>
To: Adam Roach <adam@nostrum.com>
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Subject: Re: [MMUSIC] Simulcast: Short timelines, draft impending
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Hello All As indicated by Adam in his email , we have submitted the draft defining "RID". The draft can be found here: https://datatracker.ietf.org/doc/draft-pthatcher-mmusic-rid/?include_text=1 Please provide your feedback on the same. Thanks Suhas On Thu, Sep 24, 2015 at 7:34 PM, Adam Roach <adam@nostrum.com> wrote: > At the W3C WebRTC interim meeting a couple of weeks ago, one of the issues > that the group was not able to resolve was how to enable the use of > simulcast for WebRTC browser implementations. A key point of contention was > the use of unique payload types for each simulcast encoding in the current > MMUSIC document (draft-ietf-mmusic-sdp-simulcast-01). Combined with the > other features planned for WebRTC, there is concern that such an approach > may lead to PT exhaustion within a session under certain reasonably > expected circumstances. > > > As important context: the WebRTC 1.0 specification is rapidly approaching > finalization, and the working group hopes to leave the TPAC meeting at the > end of October with all of the loose ends tied up. Simulcast is one of the > more important and one of the most loose ends in the specification at the > moment. As a result, we sincerely hope that we can come to consensus on a > viable approach in MMUSIC over the next few weeks. To be explicit: the TPAC > meeting is the week before the Yokohama IETF meeting, so we cannot afford > to wait for the ordinary meeting-driven work schedule to push simulcast > along. We hope to foster a useful and productive conversation on the > mailing list well ahead of IETF 94. > > > While there were some “hallway discussions” in Prague to discuss potential > approaches that would address these concerns, none of these have yet been > documented and shared with the mailing list. > > > After significant conversations both at and after the interim WebRTC > meeting, and considering information about the type of solutions that > interested parties are likely to find acceptable, a number of the WebRTC > participants have come up with a tentative proposal that we believe is > likely to be simple, flexible, and satisfactory to everyone involved. At a > high level: > > > * > > The current behavior described in the MMUSIC simulcast draft remains > valid. > > * > > Additionally, we define a new attribute type (provisionally called > “RID”, for “RTP Stream ID”) that can be used to define additional > codec-independent constraints on PTs (e.g., max-fps, max-bps, > max-width, max-height). > > * > > RIDs can be defined to be unidirectional, so as to allow > implementations to signal the ability to send a different number of > encodings than they can receive. > > * > > The values for each constraint can be specified to be different in > each direction. > > * > > When used, the RID value is encoded as part of the RTP packet, in an > extension header. > > * > > The values (that is, identifiers) used for RID are proposed by the > offerer in a session, and are symmetric. The RID values in an answer > must be a subset of those present in the offer. > > * > > The parameters associated with a RID can be made more restrictive > (i.e., resolution decreased, bandwidth decreased), but not less > restrictive, in an answer. > > * > > For those sessions that use RIDs, the “a=simulcast” parameter is > enhanced to be able to carry RIDs instead of PTs. > > > We hope to have an internet-draft that describes this approach in more > detail by the end of next week. > > /a > > _______________________________________________ > mmusic mailing list > mmusic@ietf.org > https://www.ietf.org/mailman/listinfo/mmusic >
- [MMUSIC] Simulcast: Short timelines, draft impend… Adam Roach
- Re: [MMUSIC] Simulcast: Short timelines, draft im… Harald Alvestrand
- Re: [MMUSIC] Simulcast: Short timelines, draft im… Byron Campen
- Re: [MMUSIC] Simulcast: Short timelines, draft im… Suhas Nandakumar
- [MMUSIC] Comments on draft-pthatcher-mmusic-rid-00 Paul Kyzivat
- Re: [MMUSIC] Simulcast: Short timelines, draft im… Flemming Andreasen
- Re: [MMUSIC] Simulcast: Short timelines, draft im… Magnus Westerlund
- Re: [MMUSIC] Simulcast: Short timelines, draft im… Flemming Andreasen
- Re: [MMUSIC] Comments on draft-pthatcher-mmusic-r… Byron Campen
- Re: [MMUSIC] Comments on draft-pthatcher-mmusic-r… Byron Campen
- Re: [MMUSIC] Comments on draft-pthatcher-mmusic-r… Byron Campen