Re: [rtcweb] Proposed Plan for Usage of SDP and RTP - Lower level API minus SDP
Roman Shpount <roman@telurix.com> Thu, 07 March 2013 18:44 UTC
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From: Roman Shpount <roman@telurix.com>
To: Peter Thatcher <pthatcher@google.com>
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Cc: "<rtcweb@ietf.org>" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Proposed Plan for Usage of SDP and RTP - Lower level API minus SDP
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I very strongly agree. I think having an API independent from SDP will allow the group to concentrate on the actual features instead of arguing about the useless blob syntax. I was initially proponent of Offer/Answer but once I started using the actual API, I saw offer/answer presenting nothing but problems. I actually see current WebRTC SDP offer/answer implementation as a hindrance to SIP interop. It provides a much more coarse API then typically present in SIP client. That in turns forces WebRTC implementer to make decision for a developer that create interop problems (like no way to switch send codecs without changing transport parameters). _____________ Roman Shpount On Thu, Mar 7, 2013 at 1:33 PM, Peter Thatcher <pthatcher@google.com> wrote: > A question for all of you in the "please don't make us use SDP as an > API forever" crowd (and I include myself): Would it be acceptable to > you to have an intermediate step where we keep createOffeer, > setRemoteDescription and setLocalDescription as-is, but allow a JSON > argument? It seems to be that such a thing could provide all the same > low-level of control as any other setup of methods, but may be much > more likely to be accepted by the group as a whole. And, it would > still be a lot more pleasant for application developers, and leave > more flexibility for a future where low-level methods might be added. > > As both an application developer and a browser implementor, I think a > good SessionDescription JSON format would be easy to implement, > pleasant to use, a small incremental step from what we currently have, > and would relieve the standards body of so much fighting over what the > SDP should look like. > > I know it wouldn't be exactly what you're looking for, but I think it > would be achievable and much better than what we have. > > If you're interested in such a thing, let me know. I might be able to > provide something a little more concrete idea as to what such a format > could be. > > On Thu, Mar 7, 2013 at 10:23 AM, Peter Thatcher <pthatcher@google.com> > wrote: > > Hadriel, > > > > That email is great. Thank you for preserving it and for bringing it > > to our attention. I am especially sympathetic to the argument that > > it's undesirable to have the W3C tied to MMUSIC for all time. > > > > > > > > > > On Thu, Mar 7, 2013 at 8:50 AM, Hadriel Kaplan <HKaplan@acmepacket.com> > wrote: > >> > >> I knew there was a reason for posting an email for the archive machine > to store for eternity... see this: > >> http://www.ietf.org/mail-archive/web/rtcweb/current/msg01256.html > >> > >> -hadriel > >> > >> > >> On Mar 6, 2013, at 6:45 PM, Robin Raymond <robin@hookflash.com> wrote: > >> > >>> > >>> Do we need SDP "blob" format in the exchange in the first place? All > media > >>> can be done without SDP given an intelligent stream API. An API already > >>> exists to create these streams (albeit somewhat lacking if we remove > the > >>> SDP 'blob'). This API helps "simplify" creating this blob for later > >>> exchange. But the blob is truly not needed. Each side could in fact > create > >>> the desired streams, pass in the appropriate media information such as > >>> codecs and ICE candidates and chose the socket pair to multiplex upon. > >>> Yes, it's a bit more low level but it certainly can be done (and > cleanly). > >>> > >>> https://datatracker.ietf.org/doc/draft-jennings-rtcweb-plan/ > >>> > >>> Nothing wrong with the draft in an SDP/SIP mindset but I'm going to > take > >>> it from a totally different non-SDP angle. I have to say, the ideas > >>> presented are very good. I appreciate FEC, and synchronizing streams is > >>> cool. But SDP isn¹t needed to do it. Let me as the programmer worry > about > >>> how to manage streams and the features on the streams and associations > >>> between the streams via an API only. > >>> > >>> Point 4, 5 and 6 in the specification all have to do with the > complexities > >>> of having to describe the intentions of mixing in SDP. So no comment > >>> beyond ³don¹t use SDP². > >>> > >>> As for 7.1 ³this is because the sender choses the SSRC² only true > >>> because we are forced to use SDP and the assumptions is that it¹s SIP. > We > >>> could have the receiver dictate what the sender should use in advance > of > >>> any media. In our case, we establish in advance what we want from all > >>> parties before even ³ringing² the other party. We do not have SSRC > >>> collisions as we reversed the scenario allowing the receiver to pick > the > >>> expected SSRC. Coordinating the streams is a problem with SIP because > of > >>> how they do forking/conferencing. This specification forces this issue > on > >>> those not using SIP. If SIP has problems with streams arriving early to > >>> their stateful offer/answer then let them worry about ³how² they > intend to > >>> match the streams at a higher SDP layer and get this draft out of the > >>> RTCWEB track on the SIP track. To be clear, the proposal seems entirely > >>> reasonable and intelligent for SIP/SDP. But it¹s way to SIP centric for > >>> general use. > >>> > >>> On that note, what I do need in the API is an ability to dictate the > SSRC > >>> when I create an RTP stream for sending (should I care to do that). > >>> > >>> 7.2 Multiple render > >>> > >>> Again this is an issue of SIP/SDP. We can control the SSRCs to split > them > >>> out to allow multiplexing easily on the same RTP ports with multiple > >>> parties/sources. If given the primitives to control the streams just, > this > >>> specification could be used to dictate how to negotiate issues in their > >>> space. > >>> > >>> 7.2.1 I¹m feeling the pain. How about just giving me an API where I can > >>> indicate what streams are FEC associated. > >>> > >>> 7.3 Give me API to give crypto keys to RTP layer. Let me handle the > >>> fingerprint and security myself beyond that. > >>> > >>> 8. Let's just say politely that I would not want to be the developer > >>> assigned to programming around all this stuff. > >>> > >>> Again, a perfect illustration why I don¹t want SDP. > >>> > >>> Media is complicated for good reason as there are many untold use > cases. > >>> The entire IETF/W3C discussion around video constraints illustrates > some > >>> of the complexities and competing desires for just one single media > type. > >>> If we tie ourselves to SDP we are limiting ourselves big time, and > some of > >>> the cool future stuff will be horribly hampered by it. > >>> > >>> My issues with SDP can be summarized as: > >>> > >>> - unneeded - much too high level an API > >>> - arcane format - legacy and problematic > >>> - offer/answer > >>> - incompatibilities > >>> - lack of API contact > >>> - doesn't truly solve goal of interoperability with legacy systems (eg. > >>> SIP) > >>> > >>> Regret that I did not have time for feedback earlier. As you can tell, > I > >>> am not at all happy with where we sit today wrt requiring SDP. IMHO we > >>> need a lower level API if we are going to insist on using SDP. > >>> > >>> > >>> You can read my entire (long) rant against SDP here > >>> http://blog.webrtc.is/2013/03/06/sdp-the-webrtc-boat-anchor/ > >>> > >>> > >>> > >>> _______________________________________________ > >>> rtcweb mailing list > >>> rtcweb@ietf.org > >>> https://www.ietf.org/mailman/listinfo/rtcweb > >> > >> _______________________________________________ > >> rtcweb mailing list > >> rtcweb@ietf.org > >> https://www.ietf.org/mailman/listinfo/rtcweb > _______________________________________________ > rtcweb mailing list > rtcweb@ietf.org > https://www.ietf.org/mailman/listinfo/rtcweb >
- [rtcweb] Proposed Plan for Usage of SDP and RTP -… Robin Raymond
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Hadriel Kaplan
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Martin Thomson
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Mary Barnes
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Eric Rescorla
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Roman Shpount
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Eric Rescorla
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Mary Barnes
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Erik Lagerway
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Silvia Pfeiffer
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Iñaki Baz Castillo
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Iñaki Baz Castillo
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Silvia Pfeiffer
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Silvia Pfeiffer
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Iñaki Baz Castillo
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Roman Shpount
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Matthew Kaufman
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Iñaki Baz Castillo
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Silvia Pfeiffer
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Matthew Kaufman
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Silvia Pfeiffer
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Timothy B. Terriberry
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Silvia Pfeiffer
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Timothy B. Terriberry
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Harald Alvestrand
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Stefan Håkansson LK
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Robin Raymond
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Stefan Håkansson LK
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Stefan Håkansson LK
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Stefan Håkansson LK
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Peter Thatcher
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Matthew Kaufman (SKYPE)
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Matthew Kaufman (SKYPE)
- [rtcweb] Division of labor (Re: Proposed Plan for… Harald Alvestrand
- Re: [rtcweb] Division of labor (Re: Proposed Plan… Matthew Kaufman
- Re: [rtcweb] Proposed Plan for Usage of SDP and R… Justin Uberti
- [rtcweb] Separating stream manipulation from the … Harald Alvestrand
- Re: [rtcweb] Separating stream manipulation from … Peter Thatcher
- Re: [rtcweb] Separating stream manipulation from … Stefan Håkansson LK
- Re: [rtcweb] Separating stream manipulation from … Harald Alvestrand
- Re: [rtcweb] Separating stream manipulation from … Ted Hardie
- Re: [rtcweb] Separating stream manipulation from … Martin Thomson
- Re: [rtcweb] Separating stream manipulation from … Silvia Pfeiffer
- Re: [rtcweb] Separating stream manipulation from … Suhas Nandakumar
- Re: [rtcweb] Separating stream manipulation from … Silvia Pfeiffer
- Re: [rtcweb] Separating stream manipulation from … Harald Alvestrand
- Re: [rtcweb] Separating stream manipulation from … Dale R. Worley