Re: [MMUSIC] Proposal for what bundle should say about demux
Emil Ivov <emcho@jitsi.org> Fri, 24 May 2013 07:08 UTC
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Date: Fri, 24 May 2013 10:08:00 +0300
From: Emil Ivov <emcho@jitsi.org>
Organization: Jitsi
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To: "Cullen Jennings (fluffy)" <fluffy@cisco.com>
References: <C5E08FE080ACFD4DAE31E4BDBF944EB11350F3C8@xmb-aln-x02.cisco.com> <519E80E4.6010904@jitsi.org> <C5E08FE080ACFD4DAE31E4BDBF944EB11351027A@xmb-aln-x02.cisco.com>
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Cc: mmusic WG <mmusic@ietf.org>
Subject: Re: [MMUSIC] Proposal for what bundle should say about demux
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Hey Cullen, On 24.05.13, 01:22, Cullen Jennings (fluffy) wrote: > > <snip> > > What I had in mind was something along the lines of the following > > A is sending an offer that forks to B and C. A and B support the new > mechanisms but C does not. A has no idea if the things it is talking > to support the new thing. Exactly. > A constructs an offer that in the SDP has an indication it can > receive the header extension. Perhaps something like > "a=new-hdr-ext=123456". The new header extension allows one to embed > an identifer in the RTP packets and this SDP indicates that the > identifier should be 123456 for RTP with this mapping. OK. > A sends the offer and it arrives at both B and C. C does not > understand it and just ignores it. B understands it and inserts a TP > header extension with the identifier 123456. > > Imagine the RTP packets from B and C arrive at A before any SDP > answer. A looks at the RTP packet from B, and see the header exertion > and reads out the identifier 123456 and now knows the mapping. A > looks at the RTP packet from C and does not see the RTP header > extension so it carries on to try other things. That's it. This is the point that I am talking about. In order for A to be able to fall back to something, it needs to have attributed PTs such that they could be used for demuxing. So in other words: when constructing your offer, whatever you do, you MUST make sure that your PTs would be enough for you to match to m= lines, UNLESS you are certain that the other party would support some other mechanism for doing the same. Does this make sense? > So yes, as you point out, for the packets from C where it can't use > PT, it needs to fall back to SSRC SSRC is also a non-guaranteed approach because you don't know if C is going to pre-announce them in SDP. Emil -- https://jitsi.org
- [MMUSIC] Proposal for what bundle should say abou… Cullen Jennings (fluffy)
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Emil Ivov
- Re: [MMUSIC] Proposal for what bundle should say … Martin Thomson
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Mo Zanaty (mzanaty)
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Dale R. Worley
- Re: [MMUSIC] Proposal for what bundle should say … Cullen Jennings (fluffy)
- Re: [MMUSIC] Proposal for what bundle should say … Martin Thomson
- Re: [MMUSIC] Proposal for what bundle should say … Emil Ivov
- Re: [MMUSIC] Proposal for what bundle should say … Emil Ivov
- Re: [MMUSIC] Proposal for what bundle should say … Kevin Dempsey
- Re: [MMUSIC] Proposal for what bundle should say … Emil Ivov
- Re: [MMUSIC] Proposal for what bundle should say … Kevin Dempsey
- Re: [MMUSIC] Proposal for what bundle should say … Emil Ivov
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Emil Ivov
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Emil Ivov
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Colin Perkins
- Re: [MMUSIC] Proposal for what bundle should say … Christer Holmberg
- Re: [MMUSIC] Proposal for what bundle should say … Cullen Jennings (fluffy)
- Re: [MMUSIC] Proposal for what bundle should say … Cullen Jennings (fluffy)
- Re: [MMUSIC] Proposal for what bundle should say … Colin Perkins
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Colin Perkins
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Colin Perkins
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Colin Perkins
- Re: [MMUSIC] Proposal for what bundle should say … Paul Kyzivat
- Re: [MMUSIC] Proposal for what bundle should say … Mary Barnes
- Re: [MMUSIC] Proposal for what bundle should say … Cullen Jennings (fluffy)
- Re: [MMUSIC] Proposal for what bundle should say … Colin Perkins
- Re: [MMUSIC] Proposal for what bundle should say … Cullen Jennings