Re: [rtcweb] Signalling, SDP, and the way we think about interconnecting RTCWEB applications
Neil Stratford <neils@belltower.co.uk> Sat, 15 October 2011 14:10 UTC
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Date: Sat, 15 Oct 2011 15:10:33 +0100
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From: Neil Stratford <neils@belltower.co.uk>
To: Harald Alvestrand <harald@alvestrand.no>
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Subject: Re: [rtcweb] Signalling, SDP, and the way we think about interconnecting RTCWEB applications
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On Sat, Oct 15, 2011 at 2:44 PM, Harald Alvestrand <harald@alvestrand.no>wrote: > ** > On 10/15/2011 02:08 PM, Neil Stratford wrote: > > On Sat, Oct 15, 2011 at 12:29 PM, Harald Alvestrand <harald@alvestrand.no>wrote: > >> >>> Remember that: >> a) codecs are (currently) part of the platform, not of the application. >> b) one of our aims for negotiation is that if application X is deployed in >> browsers A and B, and both browser A and B support a "best codec" W that was >> created *after* X was last updated, then the codec W should be used. >> >> Given the last point - the app *cannot* "implicitly" what codec will be >> used. And given that it doesn't know the codec, it can't know the parameters >> either. >> >> (that said... I'm all in favour of fewer parameters. The RTP format for >> VP8 that we're in the process of finishing has zero parameters. I hope it >> will remain that way. > > > Can we work around this issue by delegating parameter negotiation to the > codec itself? Each codec in the codec capability list could present (at a > minimum) it's name, priority and a codec specific parameter negotiation > function. We can then delegate the complicated codec specific details (when > necessary) without needing any advance knowledge in the javascript > application. We would need to standardise the parameter lists such that > different codec implementations can interop, but that is the same with SDP. > > Yes, maybe we could do that. But would it make a difference? > > SDP is (among other things) exactly such a parameter list standardisation, > each and every codec deployed with RTP tends to publish a specification on > how to encode those parameter lists in SDP, and each and every video engine > implementing those codecs tends to have code in it that parses that SDP and > does the negotiation on that basis. > > Are we reinventing another encoding format for SDP again? > I guess there are a couple of points here: 1. Yes, we are re-inventing SDP, but at a lower level, so we leave it up to the developer to use SDP, or something else if they prefer. 2. I fully support that we need to interop with SIP, and that we should make that a simple thing to do. However, I also think that rtcweb will rapidly become the dominant RTC platform due to the pervasiveness of browsers. Codec developers will be targeting rtcweb as a primary platform, especially if we make it easy to download and deploy new codecs. Neil
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- [rtcweb] Signalling, SDP, and the way we think ab… BeckW
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- Re: [rtcweb] Signalling, SDP, and the way we thin… Randell Jesup
- Re: [rtcweb] Signalling, SDP, and the way we thin… Hadriel Kaplan
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- Re: [rtcweb] Signalling, SDP, and the way we thin… Hadriel Kaplan
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- Re: [rtcweb] Signalling, SDP, and the way we thin… Ted Hardie
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- Re: [rtcweb] Signalling, SDP, and the way we thin… Hadriel Kaplan
- Re: [rtcweb] Signalling, SDP, and the way we thin… Ted Hardie
- Re: [rtcweb] Signalling, SDP, and the way we thin… Dzonatas Sol
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- Re: [rtcweb] Signalling, SDP, and the way we thin… Neil Stratford
- Re: [rtcweb] Signalling, SDP, and the way we thin… Wolfgang
- Re: [rtcweb] Signalling, SDP, and the way we thin… Harald Alvestrand
- Re: [rtcweb] Signalling, SDP, and the way we thin… Neil Stratford
- Re: [rtcweb] Signalling, SDP, and the way we thin… Wolfgang
- Re: [rtcweb] Signalling, SDP, and the way we thin… Harald Alvestrand
- Re: [rtcweb] Signalling, SDP, and the way we thin… Neil Stratford
- Re: [rtcweb] Signalling, SDP, and the way we thin… Roy, Radhika R USA CIV (US)
- Re: [rtcweb] Signalling, SDP, and the way we thin… Stephan Wenger
- [rtcweb] VP8 and parameters (Re: Signalling, SDP,… Harald Alvestrand
- Re: [rtcweb] Signalling, SDP, and the way we thin… Wolfgang
- Re: [rtcweb] Signalling, SDP, and the way we thin… Dzonatas Sol
- Re: [rtcweb] Signalling, SDP, and the way we thin… Randell Jesup
- Re: [rtcweb] Signalling, SDP, and the way we thin… Wolfgang
- Re: [rtcweb] Signalling, SDP, and the way we thin… Randell Jesup
- Re: [rtcweb] Signalling, SDP, and the way we thin… Wolfgang Beck
- Re: [rtcweb] Signalling, SDP, and the way we thin… Iñaki Baz Castillo
- Re: [rtcweb] Signalling, SDP, and the way we thin… Ted Hardie
- Re: [rtcweb] Signalling, SDP, and the way we thin… Dzonatas Sol
- Re: [rtcweb] Signalling, SDP, and the way we thin… Randell Jesup
- Re: [rtcweb] Signalling, SDP, and the way we thin… Wolfgang Beck
- Re: [rtcweb] Signalling, SDP, and the way we thin… Cullen Jennings