Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subsequent Offers
Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com> Thu, 07 November 2013 18:10 UTC
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From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
To: Martin Thomson <martin.thomson@gmail.com>, Justin Uberti <juberti@google.com>
Thread-Topic: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subsequent Offers
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Date: Thu, 07 Nov 2013 18:06:58 +0000
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subsequent Offers
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On 07/11/13 18:52, "Martin Thomson" <martin.thomson@gmail.com> wrote: >On 6 November 2013 23:11, Justin Uberti <juberti@google.com> wrote: >>> >>> A more complex case is: >>> X offers A, B, C >>> Y answers A, B >>> >>> Then X begins using A, and not using B. >>> When doing next offer, >>> 1) X MUST offer A, B, C >>> 2) X MUST offer A, B >>> 3) X MUST offer A >>> 4..N) X MUST offer one of above by default, but may offer more >>>according >>> to some constraint. >>> >> >> X may be using A in this case, but Y may be using B, so #3 would be bad >>IMO. >> (Remember, the reason for the new offer is because some other property >>of >> the session changed.) >> >> #2 would be the default behavior, and #1 would be the optional behavior >>that >> the application could choose. > >Thanks to Paul for the example, and I definitely agree with the >requirement that the negotiated (not just in-use) parameters MUST >remain. That's a given. > >My suggestion is that we *don't* add a constraint, we just require the >inclusion of everything. If you want to constrain codec use, then you >can use the mechanisms that we provide for doing that. Currently, >that's editing SDP; though we've talked about specific constraints in >the form of { video: { disableCodec: 'VP8' } } or something like that. At the last WebRTC teleconf we discussed what media transmission related constraints we should have for v1, and the consensus at that meeting was clear: codec selection was not one of them. So if you have to remove codec(s) from the offer that would have to be done by SDP mangling. I guess that I¹m trying to say that your suggestion is in line with consensus at that meeting at least, and also in line with my personal opinion. > >I don't want to create a special new set of constraints that will >effectively never get used. I agree. > >(We do need to be careful about overconstraining implementations by >using MUST here. Implementations should be encouraged to offer >everything that they can do, but circumstances might change such that >even negotiated codecs can become unavailable. Any MUST will need to >be modulated.) >_______________________________________________ >rtcweb mailing list >rtcweb@ietf.org >https://www.ietf.org/mailman/listinfo/rtcweb
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Paul Kyzivat
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Parthasarathi R
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Justin Uberti
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Hutton, Andrew
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Michael Procter
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Justin Uberti
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Justin Uberti
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Hutton, Andrew
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Martin Thomson
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Hutton, Andrew
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Harald Alvestrand
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Martin Thomson
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Paul Kyzivat
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Justin Uberti
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Martin Thomson
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Subseque… Stefan Håkansson LK