Re: [MMUSIC] Questions about ICE candidates with BUNDLE
Peter Thatcher <pthatcher@google.com> Fri, 13 November 2015 22:53 UTC
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From: Peter Thatcher <pthatcher@google.com>
Date: Fri, 13 Nov 2015 14:52:32 -0800
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To: Christer Holmberg <christer.holmberg@ericsson.com>
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Subject: Re: [MMUSIC] Questions about ICE candidates with BUNDLE
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On Fri, Nov 13, 2015 at 2:14 PM, Christer Holmberg < christer.holmberg@ericsson.com> wrote: > Hi, > > >>>1. It says "answerer MUST assign shared ICE candidates to each bundled > 'm=' line ... in the answer". What is > >>>the reasoning for duplicating candidates in this way in the answer? > Clearly at this point, the offerer understands > >>>BUNDLE and BUNDLE is negotiated, and the offerer (when using > bundle-only) doesn't include duplicate candidates, > >>>so what's value in duplicating the candidates in the answer? If there > isn't a good reason, I'd prefer to not duplicate > >>>them, even if that means using 'a=bundle-only' in the answer (which is > currently unspecified) > >> > >>At an early stage, we made a design decision that we’ll explicitly > include all information in each m- line (like we do for non-BUNDLE), even > if that means duplicating information. > >> > >>Otherwise we have to define procedures what happens if the m- line, in > which the candidates were included, is e.g. later removed > >>from the BUNDLE group. Then the candidates have to be assigned to some > other m- line within the BUNDLE group, to make sure > >>they are “seen” in the current SDP associated with the BUNDLE group. Etc. > > > > But that's not true for offers. Offers can put "a=bundle-only" in the > m-line and then leave out ICE candidates. So why can't answers do that > also? > > The reason you don't need to include candidates in a bundle-only m- line > is so that you don't need to reserve unique candidates for the m- line (as > the m- line is not going to be used unless it's placed in a bundle group, > and hence will share the candidates associated with the bundle group). In the case of an m-line in an answer that is an answer to a bundle-only m-line in an offer, the same logic applies: the m-line is not going to be used unless it's place in a bundle group, so you don't need to reserve unique candidates, so you don't need to include any candidates. > That is not an issue in the answer, as the same candidates can be assigned > to each m- line in the bundle group. > > I thinking mandating the candidates be duplicated in the answer has three issues: 1. It conflicts with trickle ICE. 2. It's slightly more complex to implement (we have to go add extra logic to go duplicate these things) 3. It's a complete waste of time/space/effort. The recipient of these duplicate candidates is never going to anything with them. > Also keep in mind that, when a subsequent offer is sent, the bundle-only > attribute is no longer used. Can you point out where in the draft it says that? I tried finding it and I had a difficult time seeing where bundle-only wasn't allowed in a reoffer. > Would you then also in the subsequent offer only assign possible > candidates to only one m- line within the bundle group? > That sounds logical to me. They aren't included in the first offer. Why add them to subsequent offers? It's inconsistent, and a waste. > > >>> 2. If the answerer does not include any candidates in the answer and > instead trickles them later, should it trickle them > >>> N times (once for each m-line in the BUNDLE group) or >1 time? 1 time > seems much more reasonable than N times, but > >>> if we duplicate candidates in the answer, but not duplicate them while > trickling, that's a bit inconsistent. Yet >another reason to not duplicate > in the answer :). > >> > >> Assuming you use SDP to signal the trickled candidates, it’s true that > you would duplicate them, > >> > >What's the rationale for that? These duplicates provide no value, and > in the case of many m-lines (such as a conferencing > >system with many participants), we could be talking about 30x the number > of candidates being signaled. > > I hear what you are saying. > > But, if we would do a change, we also need to look at the full picture, > and consider subsequent offers etc. > I think a simple rule would be "if you know it's going to be bundled onto another m-line, don't include candidates". That would go for bundle-only m-lines in an offer, bundled m-lines in an answer, and bundled m-lines in a re-offer. > > > but you would still indicate each in a single SDP message sent towards > the offerer. > > > > The default behavior of trickle ICE webrtc is for the "onicecandidate" > > event to have one candidate in each event, which means the simple > WebRTC application will be signalling > > each candidates individually. For a single SDP message to contain many > candidates, the application would > > have to implement some form of candidate batching. But a smart > application wouldn't bother doing that. > > It would just de-duplicate the candidates instead. Which means it would > just be counteracting this duplication. > > > This seems like just a silly waste to me, especially since it's > apparently only required on the answerer side, and not on the offerer side. > > Why don't you think it's needed on the offerer side? Are you saying that, > in subsequent offers, each m- line would contain duplicated candidates? > > I was referring only to initial offers, where they aren't duplicated. But as I mentioned, I think bundle-only m-lines should contain in subsequent offers should contain the same candidates as the initial offer (+ trickled candidates). There's no reason to duplicate candidates in a subsequent offer. > Regards, > > Christer > >
- [MMUSIC] Questions about ICE candidates with BUND… Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Bernard Aboba
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Paul Kyzivat
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Paul Kyzivat
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Roman Shpount
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Peter Thatcher
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Paul Kyzivat
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Paul Kyzivat
- Re: [MMUSIC] Questions about ICE candidates with … Justin Uberti
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Suhas Nandakumar
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Suhas Nandakumar
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Taylor Brandstetter
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Taylor Brandstetter
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg
- Re: [MMUSIC] Questions about ICE candidates with … Taylor Brandstetter
- Re: [MMUSIC] Questions about ICE candidates with … Christer Holmberg