Re: [rtcweb] Proposed Plan for Usage of SDP and RTP - Lower level API minus SDP
Peter Thatcher <pthatcher@google.com> Thu, 07 March 2013 18:34 UTC
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From: Peter Thatcher <pthatcher@google.com>
Date: Thu, 07 Mar 2013 10:33:44 -0800
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To: Hadriel Kaplan <HKaplan@acmepacket.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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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] 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