Re: [rtcweb] SDP is not suitable for WebRTC
Iñaki Baz Castillo <ibc@aliax.net> Mon, 29 July 2013 17:50 UTC
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Date: Mon, 29 Jul 2013 19:49:58 +0200
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From: Iñaki Baz Castillo <ibc@aliax.net>
To: Bossiel thioriguel <bossiel@yahoo.fr>
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Cc: rtcweb@ietf.org, public-webrtc@w3.org
Subject: Re: [rtcweb] SDP is not suitable for WebRTC
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Thanks a lot for clarifying it. So Christer was wrong ;) And it makes my scenario even worse. I really hope something will happen and WebRTC will get rid of SDP... -- Iñaki Baz Castillo <ibc@aliax.net> El 29/07/2013 19:45, "Bossiel thioriguel" <bossiel@yahoo.fr> escribió: > You said: "2) > > SDP seems to allow that the offer and the answer have different number > of m lines " > > No at all: > RFC 3264: > For each "m=" line in the offer, there MUST be a corresponding "m=" > > line in the answer. The answer MUST contain exactly the same number > of "m=" lines as the offer. This allows for streams to be matched up > based on their order. This implies that if the offer contained zero > "m=" lines, the answer MUST contain zero "m=" lines. > > Mamadou. > > ------------------------------ > *De :* Iñaki Baz Castillo <ibc@aliax.net> > *À :* "rtcweb@ietf.org" <rtcweb@ietf.org>; "public-webrtc@w3.org" < > public-webrtc@w3.org> > *Envoyé le :* Lundi 29 juillet 2013 19h31 > *Objet :* [rtcweb] SDP is not suitable for WebRTC > > Hi, I initiated a thread [*] about Plan-Unified and multiple m lines, > but it was moved to MMUSIC maillist (don't know why since it is about > WebRTC applications design): > > http://www.ietf.org/mail-archive/web/mmusic/current/msg11966.html > > Sorry for the cross-posting but at this point I'm a bit lost and do > not know which is the appropriate group for my concern. > > > > So my concern is: > > > - Web application with a SIP over WebSocket client running in the web. > > - The web user is provided with a conference SIP URI in which there > are *already* 8 participants (5 of them emitting audio and video and 3 > just emitting audio). > > - The user calls, from his webphone, to the given URI to join the > conference. > > > > Let's imagine that the JS app knows the number of participant in the > conference. > Let's imagine my browser have mic and webcam. > > > > QUESTION: > > How can my browser join the conference without requiring SDP > renegotiation from the server and, at the same time, being able to > send audio/video and receive audio/video from others (different tracks > / m=lines)? > > > > > "SOLUTIONS": > > > > 1) > > I tell my browser to generate a SDP offer with: > > - 1 send/receive m=audio line. > - 7 recvonly m=audio line. > - 1 send/only m=video line. > - 4 recvonly m=video line. > > (Obviously this is a joke) > > > > 2) > > SDP seems to allow that the offer and the answer have different number > of m lines (I'm not aware of that but I believe that SDP can do > "everything"). So my browser generates a SDP offer with 1 m=audio line > and 1 m=video line, and the server replies with 8 m=audio lines and 4 > m=video lines. > > Will my browser understand such a SDP answer with more m lines than > its generated offer? I assume NOT. > > > > 3) > > My browser generates a SDP offer with 1 m=audio line and 1 m=video > line and the server too. And later the server sends re-INVITE with all > the m lines. > > Oppss, SDP renegotiation... > > > > > SDP is bad for WebRTC. SDP is good for legacy symmetric communications > in which there is a single-track audio communication and, of course, > both endpoints emit audio. But SDP is bad for modern RTC protocols in > which an endpoint can emit tons of tracks to a single endpoint. > > > Do we really want this for WebRTC 1.0 ? > > > -- > Iñaki Baz Castillo > <ibc@aliax.net> > _______________________________________________ > rtcweb mailing list > rtcweb@ietf.org > https://www.ietf.org/mailman/listinfo/rtcweb > > >
- [rtcweb] SDP is not suitable for WebRTC Iñaki Baz Castillo
- Re: [rtcweb] SDP is not suitable for WebRTC piranna@gmail.com
- Re: [rtcweb] SDP is not suitable for WebRTC Bossiel thioriguel
- Re: [rtcweb] SDP is not suitable for WebRTC Iñaki Baz Castillo
- Re: [rtcweb] SDP is not suitable for WebRTC Silvia Pfeiffer
- Re: [rtcweb] SDP is not suitable for WebRTC Ron
- Re: [rtcweb] SDP is not suitable for WebRTC Christer Holmberg
- Re: [rtcweb] SDP is not suitable for WebRTC Iñaki Baz Castillo
- Re: [rtcweb] SDP is not suitable for WebRTC Iñaki Baz Castillo
- Re: [rtcweb] SDP is not suitable for WebRTC Christer Holmberg
- Re: [rtcweb] SDP is not suitable for WebRTC Iñaki Baz Castillo
- Re: [rtcweb] SDP is not suitable for WebRTC (UNCL… Roy, Radhika R CIV USARMY (US)