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

Christer Holmberg <> Fri, 18 October 2013 04:59 UTC

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From: Christer Holmberg <>
To: Suhas Nandakumar <>
Thread-Topic: [rtcweb] JSEP: Order of m- lines in multiple PeerConnections
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Date: Fri, 18 Oct 2013 04:59:22 +0000
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Subject: Re: [rtcweb] JSEP: Order of m- lines in multiple PeerConnections
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Hi Suhas,

Yes, there are a number of ways how it could be done. And, I'm not asking for a solution at this point, simply that we identify it as an issue that needs to be solved :)



Sent from my Sony Ericsson Xperia arc S

Suhas Nandakumar <> wrote:

Hi Christer,

One idea is to pass the Peer Connection Object to be forked as input to the Fork API when creating the new Peer Connection.

This way the implementation knows that the order of m=lines must   be matched to the ones in the passed in reference peer connection object ..

Any thoughts ??


On Mon, Sep 30, 2013 at 1:07 AM, Christer Holmberg <<>> wrote:

JSEP talks about the usage of multiple PeerConnection to support forking, i.e. for each new forked leg (SIP: early dialog) a new PeerConnection is created.

As has been indicated, as each new PeerConnection will have its own set of address properties, ICE properties etc, so a new Offer will have to be created and sent to inform the remote about the new properties.

So far so I good.

I also assume that the same camera/mic/etc sources are connection to each PeerConnection, so the number of m- lines in the Offer of the new PeerConnection should be the same.

However, according the 3264, the ORDER of the m- lines also need to be kept the same.

So, my question is: how can I ensure that the order of the m- lines in an Offer for a new PeerConnection is the same as in an Offer for an old PeerConnection?



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