[MMUSIC] What is an m-line?
Martin Thomson <martin.thomson@gmail.com> Mon, 13 May 2013 18:42 UTC
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Date: Mon, 13 May 2013 11:42:32 -0700
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From: Martin Thomson <martin.thomson@gmail.com>
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Subject: [MMUSIC] What is an m-line?
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We've had a great deal of discussion about plan A and B and the various interactions of these proposals with bundling. But I still don't get a good sense that there is a working consensus on what an m-line actually represents. I think that we've each reached our own conclusions, but they definitely are not consistent. We need a well-understood semantic for m-lines if we have any chance of resolving these issues; Plan A/B being only the first RTCWEB problem to address. RFC 4566 is helpfully devoid of detail, so we are free to come up with any interpretation we choose. Here are the ones that I have seen: 1. an m-line represents a single RTP session (or at least the part of the session that touches the client) This appears to be consistent with the Plan B approach 2. an m-line represents the set of RTP streams that decode into a single rendering, including layers, simulcast and FEC 3. an m-line represents a single RTP stream; multiple m-lines might be required to obtain a single rendering if it uses layers, simulcast, FEC or FID groupings This appears to be consistent with the Plan A approach In the first instance, an m-line can be multiple "things". In the latter two cases, an m-line is consistently one "thing" (or part thereof). The first interpretation has a natural advantage in terms of signaling economy and natural bundling. The latter interpretations seem to have advantages in dealing with call transfer and SSRC renumbering. So, which is correct?
- Re: [MMUSIC] What is an m-line? Paul Kyzivat
- Re: [MMUSIC] What is an m-line? Colin Perkins
- Re: [MMUSIC] What is an m-line? Bernard Aboba
- [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Paul Kyzivat
- Re: [MMUSIC] What is an m-line? Bernard Aboba
- Re: [MMUSIC] What is an m-line? Jonathan Lennox
- Re: [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Cullen Jennings (fluffy)
- Re: [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Colin Perkins
- Re: [MMUSIC] What is an m-line? Kevin Dempsey
- Re: [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Colin Perkins
- Re: [MMUSIC] What is an m-line? Harald Alvestrand
- Re: [MMUSIC] What is an m-line? Bernard Aboba
- Re: [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Emil Ivov
- Re: [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Emil Ivov
- Re: [MMUSIC] What is an m-line? Martin Thomson
- Re: [MMUSIC] What is an m-line? Emil Ivov
- Re: [MMUSIC] What is an m-line? Paul Kyzivat
- Re: [MMUSIC] What is an m-line? Paul Kyzivat
- Re: [MMUSIC] What is an m-line? Paul Kyzivat
- Re: [MMUSIC] What is an m-line? Harald Alvestrand
- Re: [MMUSIC] What is an m-line? Paul Kyzivat
- Re: [MMUSIC] What is an m-line? Suhas Nandakumar