Re: [rtcweb] RTCWeb default signaling protocol [was RE: About defining a signaling protocol for WebRTC (or not)]

Henry Sinnreich <henry.sinnreich@gmail.com> Tue, 20 September 2011 19:48 UTC

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Date: Tue, 20 Sep 2011 14:50:42 -0500
From: Henry Sinnreich <henry.sinnreich@gmail.com>
To: Hadriel Kaplan <HKaplan@acmepacket.com>, Randell Jesup <randell-ietf@jesup.org>
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Thread-Topic: [rtcweb] RTCWeb default signaling protocol [was RE: About defining a signaling protocol for WebRTC (or not)]
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Subject: Re: [rtcweb] RTCWeb default signaling protocol [was RE: About defining a signaling protocol for WebRTC (or not)]
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+1

> A full mesh is what *should* happen, but SIP/SDP can't do it, afaict.  It
> would treat them either as independent calls even at a media layer, or as a
> full-mixer conference focus model.  The closest thing we have would probably
> be the Join header, but I believe it's semantics is to join as a full mixer
> conf call.  Isn't this full-mesh media-forking thing actually a new semantic
> for SIP/SDP?  (it's hard to believe with 100+ drafts/RFCs this scenario hasn't
> already been addressed in SIP - I must be just having a memory leak)

Thanks, Henry


On 9/20/11 2:19 AM, "Hadriel Kaplan" <HKaplan@acmepacket.com>; wrote:

> 
> On Sep 20, 2011, at 2:39 AM, Randell Jesup wrote:
> 
>> On 9/20/2011 1:59 AM, Hadriel Kaplan wrote:
>>> OK, let's take the game example... only 2-player games would be able to use
>>> a simple rtcweb-SIP agent.  Anything more than 2-player would want to use
>>> the multi-party "conferencing" model of rtcweb, which can't even be signaled
>>> with SIP today as far as I can tell. (not that I've thought about it too
>>> much, but I can't see how it would without some changes to SIP)
>> 
>> It should be easy - either as N-1 2-person calls to the person hosting the
>> game, or
>> N calls via a central server (equivalent to a mixer), or as a full mesh of
>> direct
>> calls (3 2-person calls for a 3-person game, 6 for a 4-person game, etc), or
>> even
>> sparse meshes (makes sense in a game where not all players are 'near' each
>> other).
> 
> Can't do N-1 2-person calls to the person hosting the game, because rtcweb
> doesn't support "full" mixing in the browser, only local media mixing. (ie,
> everyone will hear the person hosting the game, and the person hosting the
> game will hear everyone else, but the rest won't hear each other)
> 
> Calls via a central media server require a central media server, which kinda
> defeats the "easy" concept and using our shiny new toy of rtcweb.
> 
> A full mesh is what *should* happen, but SIP/SDP can't do it, afaict.  It
> would treat them either as independent calls even at a media layer, or as a
> full-mixer conference focus model.  The closest thing we have would probably
> be the Join header, but I believe it's semantics is to join as a full mixer
> conf call.  Isn't this full-mesh media-forking thing actually a new semantic
> for SIP/SDP?  (it's hard to believe with 100+ drafts/RFCs this scenario hasn't
> already been addressed in SIP - I must be just having a memory leak)
> 
> -hadriel
> 
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