Re: [rtcweb] No Plan

Christer Holmberg <> Thu, 30 May 2013 07:44 UTC

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From: Christer Holmberg <>
To: Emil Ivov <>, "" <>
Thread-Topic: [rtcweb] No Plan
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Date: Thu, 30 May 2013 07:44:23 +0000
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Subject: Re: [rtcweb] No Plan
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Hi Emil,

The draft says:

	"For the sake of interoperability this specification strongly advises
   	against the use of multiple m= lines for a single media type."

My understanding is that the usage of multiple m= lines for a single media type would not affect the mechanism as such, but I just want to verify that :)

Also, there ARE "legacy" implementations that use multiple m= lines for a single media type (e.g. video enabled devices using two video m= lines: one for camera content, and one for slides).

So, while I definitely think that legacy interoperability shall be taken into consideration, I would not like to make such strong statements. In my opinion (the draft also talks about it), the usage of multiple simultaneous SSRCs per m- line is a much bigger issue when it comes to legacy interoperability.

Also, in CLUE we have been working on signaling scenarios with multiple m= lines per media type.



-----Original Message-----
From: [] On Behalf Of Emil Ivov
Sent: 29. toukokuuta 2013 22:00
Subject: [rtcweb] No Plan

Hey all,

Based on many of the discussions that we've had here, as well as many others that we've had offlist, it seemed like a good idea to investigate a negotiation alternative that relies on SDP and Offer/Answer just a little bit less.

The following "no plan" draft attempts to present one such approach:

The draft relies on conventional use of SDP O/A but leaves the intricacies of multi-source scenarios to application-specific signalling, with potentially a little help from RTP.

Hopefully, proponents of Plans A and B would find that the interoperability requirements that concerned them can still be met with "no plan". Of course they would have to be addressed by application-specific signalling and/or signalling gateways.

Comments are welcome!


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