Re: [rtcweb] Requesting "SDP or not SDP" debate to be re-opened
Iñaki Baz Castillo <ibc@aliax.net> Thu, 20 June 2013 23:24 UTC
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From: Iñaki Baz Castillo <ibc@aliax.net>
Date: Fri, 21 Jun 2013 01:24:09 +0200
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To: Emil Ivov <emcho@jitsi.org>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Requesting "SDP or not SDP" debate to be re-opened
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2013/6/21 Emil Ivov <emcho@jitsi.org>: > > On 20.06.13, 23:49, Iñaki Baz Castillo wrote: >> >> In JsSIP we are getting frustrated trying to implement the "hold" / >> "unhold" feature because it requires SDP parsing and mangling. Sending >> a re-INVITE with a modified SDP (now with a video track enabled) seems >> to work (after lot of pain) but we still miss a reliable API to know >> what the new SDP means. Instead we need to parse the SDP to detect >> global (or per m=) line attributes like "a=inactive" or "a=sendonly" >> etc etc. It's really painful. > > > I am having a problem following what you are trying to achieve here. In > JsSIP you seem to be going for a full SIP implementation in the browser. If > this is true and if this WG decides to remove SDP from the API surface, then > you would need to completely parse SDP in the JS and then convert it into > API calls. Similarly, when creating offers and answers you would need to > construct SDP all by yourself. And we will do it very happily because then we will know what *exactly* we are sending on-the-wire. > So I am not sure why the SDP parsing in the current situation is so much of > a blocker for your use case. Because regardless I am a SIP-guy, I understand that the main mission of WebRTC is to provide realtime communications *for* the WWW, and not to enable a new interface for like-telephony-bussines. Today I'm doing SIP. Tomorrow I may be doing [[put_here_a_future_RTC_protocol_not_based_on_SDP]] and then I don't want to be constrained by decisions made today that force any future RTC protocol to deal with SDP O/A model. :) >> BTW I don't know wheter you support PlanA, PlanB or NoPlan, but I did >> a question (in this case about NoPlan) for which I got no response, >> and honestly I would like to see it replied regardless the solution >> uses PlanA, PlanB or NoPlan model: >> >> http://www.ietf.org/mail-archive/web/rtcweb/current/msg07871.html >> > The other option would be indeed to do the same thing in JS. I believe this > is JsSIP's use case. In that case however, regardless of whether you choose > Plan A, Plan B, No Plan or CU-RTC-Web, you will inevitably be exposed to a > fair amount of complexity, parsing and JS magic. > > You are, after all, building a SIP stack. Yes, but JsSIP creates its own SIP messages to be sent in the wire, so we have full control over *what* we create and send. Those SIP messages are not provided by the WebRTC API. But for the SDP component, JsSIP retreives a SDP blob string from the PC. > > In the above mail you also say: > >> Another example: >> >> * I am a powerful SIP conference server which properly implements >> WebRTC. I initiate a call to 5 users (running JS SIP app in their >> browsers). The initial INVITE has SSRC/MSID fields in the SDP >> identifying all the participants, am I right? > > > No, with No Plan there are no SSRCs and MSIDs in the SDP that comes from the > browser. OK >> * Later, during the conference, I call to another 6th participant and >> enter him into the conference, so I need to send a re-INVITE to every >> participant with a modified version of the SDP (note that this is SIP >> protocol, so I need to use SIP messages to carry the new info about >> SSRC/MSID and so on). > > > That's the thing. You don't need that. In Jitsi we do exactly this operation > with no Offer/Answer signalling. RTP carries enough information to process > streams and we use upper layer signalling (4575) for things such as mapping > SSRCs to users and announcing current participant list. That is much better than Plan A and Plan B. BTW: What would happen in NoPlan if the remote (i.e. a SIP gateway/endpoing) sends you a re-INVITE for "hold" purposes and you pass the SDP to your PC? or you should not pass the SDP to your PC? and if so, what about if the SDP contains updated ICE candidates due to remote peer network mobility? Thanks a lot for your response. -- Iñaki Baz Castillo <ibc@aliax.net>
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Roman Shpount
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Alexandre GOUAILLARD
- [rtcweb] Requesting "SDP or not SDP" debate to be… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Erik Lagerway
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Ted Hardie
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Adam Roach
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman (SKYPE)
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Martin Thomson
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Roman Shpount
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Christer Holmberg
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Christer Holmberg
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Christer Holmberg
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Hutton, Andrew
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman (SKYPE)
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman (SKYPE)
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Christer Holmberg
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Martin Thomson
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Christer Holmberg
- [rtcweb] Priorities - Was: Requesting "SDP or not… Hutton, Andrew
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Harald Alvestrand
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Roman Shpount
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Matthew Kaufman (SKYPE)
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Hutton, Andrew
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Iñaki Baz Castillo
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Peter Thatcher
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Hutton, Andrew
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Harald Alvestrand
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Bernard Aboba
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Bernard Aboba
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Richard Barnes
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Hutton, Andrew
- Re: [rtcweb] Priorities - Was: Requesting "SDP or… Parthasarathi R
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Emil Ivov
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Bossiel thioriguel
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Bossiel thioriguel
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Hutton, Andrew
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Hutton, Andrew
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Robin Raymond
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Peter Thatcher
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Bossiel thioriguel
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Bossiel thioriguel
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Iñaki Baz Castillo
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Roman Shpount
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Roman Shpount
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Hutton, Andrew
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Matthew Kaufman (SKYPE)
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Silvia Pfeiffer
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Bossiel thioriguel
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Silvia Pfeiffer
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Roman Shpount
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Roman Shpount
- Re: [rtcweb] Requesting "SDP or not SDP" debate t… Martin Thomson