Re: [rtcweb] JSEP: Order of m- lines in multiple PeerConnections

Christer Holmberg <> Fri, 18 October 2013 18:28 UTC

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From: Christer Holmberg <>
To: "Cullen Jennings (fluffy)" <>
Thread-Topic: [rtcweb] JSEP: Order of m- lines in multiple PeerConnections
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Date: Fri, 18 Oct 2013 18:28:35 +0000
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Subject: Re: [rtcweb] JSEP: Order of m- lines in multiple PeerConnections
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>>> By Invite with replaces, I mean an INVITE in new SIP dialog that uses the replaces header ( ) with the context of the old SIP dialog. 
>>> That is supported and used for lots of cases by PBX that act as B2BUA because it becomes and effective way to do things like totally change the number m-lines. 
>>> Well, when creating a new Offer to use with invite with replaces, the number of m lines don't have to match at all. You are not even required to have the same media types. So it seems like that would do it. 
>> True, but I don't think one should have to do that.
>> The initial Offer, sent by PC#1, has reached remote entities R_1 and R_2, and both have sent an Answer. For R_2 I now want to create a new PC, PC#2, and send a new Offer with the address properties of PC#2. 
> Yah, I understand - that solution is basically the cloning proposal. 

No, because I would get NEW address properties.

But, the order of the m- lines (and the media sources etc they represent), and any property that 3264 does not allow to be changed, would have to be the same.