Re: [rtcweb] Proposed Plan for Usage of SDP and RTP - Lower level API minus SDP
Martin Thomson <martin.thomson@gmail.com> Thu, 07 March 2013 17:43 UTC
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Date: Thu, 07 Mar 2013 09:43:12 -0800
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From: Martin Thomson <martin.thomson@gmail.com>
To: Hadriel Kaplan <HKaplan@acmepacket.com>
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Subject: Re: [rtcweb] Proposed Plan for Usage of SDP and RTP - Lower level API minus SDP
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Obviously I (and my employer) agree with these sentiments wholeheartedly. Both Robin and Hadriel. That doesn't change the fact that a number of people are highly motivated to protect their investment in SDP offer/answer. For those people, the pain that causes everyone else is clearly far less important than the pain they feel at this moment. So here we are. On 7 March 2013 08:50, 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