Re: [rtcweb] Multiplexing using the same port number for multiple media descritions
Justin Uberti <juberti@google.com> Tue, 30 August 2011 14:40 UTC
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From: Justin Uberti <juberti@google.com>
Date: Tue, 30 Aug 2011 10:41:57 -0400
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To: Christer Holmberg <christer.holmberg@ericsson.com>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Multiplexing using the same port number for multiple media descritions
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I think Harald's approach is cleaner, since the fallback does not require a new offer. What do you see as problematic with Harald's suggestion? On Tue, Aug 30, 2011 at 7:21 AM, Christer Holmberg < christer.holmberg@ericsson.com> wrote: > Hi, > > One possible alternative solution for SDP multiplex negotiation could be > based on the assumption of using the same port number in multiple SDP m- > lines (yes, I know SDP does not allow it, and I will come back to that). > > Something like: > > SDP offer: > > m=audio 10000 ... > a=rtpmap ... > a=rtpmap ... > m=video 10000 ... > a=rtpmap ... > a=rtpmap ... > > > SDP answer (multiplex supported/accepted): > > m=audio 20000 ... > a=rtpmap ... > a=rtpmap ... > m=video 20000 ... > a=rtpmap ... > a=rtpmap ... > > > SDP answer (multiplex not-supported/rejected): > > m=audio 20000 ... > a=rtpmap ... > a=rtpmap ... > m=video 30000 ... > a=rtpmap ... > a=rtpmap ... > > > > MAYBE there is also a need to use some kind of grouping, in which case it > could look something like (borrowing some terminology from Harald): > > > > SDP offer: > > a=group:TOGETHER foo bar > m=audio 10000 ... > a=mid:foo > a=rtpmap ... > a=rtpmap ... > m=video 10000 ... > a=mid:bar > a=rtpmap ... > a=rtpmap ... > > > SDP answer (multiplex supported/accepted): > > m=audio 20000 ... > a=rtpmap ... > a=rtpmap ... > a=mid:foo > m=video 20000 ... > a=mid:bar > a=rtpmap ... > a=rtpmap ... > > > SDP answer (multiplex not-supported/rejected): > > m=audio 20000 ... > a=rtpmap ... > a=rtpmap ... > m=video 30000 ... > a=rtpmap ... > a=rtpmap ... > > > An ISSUE with this solution is of course that SDP does not allow for it. > > However, we could always say that browsers must support it, in which case > it should work fine in direct browser-to-browser cases. > > > When interworking with legacy, I guess two things can happen: > > 1. The offer is acctepted, with different port number in the answer, and > multiplex won't be used (see example above) > > 2. The offer is rejected. In this case, the fallback would be that the > browser sends a new offer, with different port numbers, and multiplex won't > be used. > > Regards, > > Christer > > > > > _______________________________________________ > rtcweb mailing list > rtcweb@ietf.org > https://www.ietf.org/mailman/listinfo/rtcweb > >
- [rtcweb] Multiplexing using the same port number … Christer Holmberg
- Re: [rtcweb] Multiplexing using the same port num… Justin Uberti
- Re: [rtcweb] Multiplexing using the same port num… Harald Alvestrand
- Re: [rtcweb] Multiplexing using the same port num… Christer Holmberg
- Re: [rtcweb] Multiplexing using the same port num… Christer Holmberg
- Re: [rtcweb] Multiplexing using the same port num… Magnus Westerlund
- Re: [rtcweb] Multiplexing using the same port num… Christer Holmberg
- Re: [rtcweb] Multiplexing using the same port num… Harald Alvestrand
- Re: [rtcweb] Multiplexing using the same port num… Christer Holmberg