Re: [MMUSIC] Bundle offer with different ports - where to expect media?

Martin Thomson <martin.thomson@gmail.com> Thu, 23 May 2013 21:42 UTC

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Date: Thu, 23 May 2013 13:55:18 -0700
Message-ID: <CABkgnnXgvEWtAs_yYu3ZZw0_TuFtgs_aOhpTrVaYZsfGd+hk+g@mail.gmail.com>
From: Martin Thomson <martin.thomson@gmail.com>
To: "Cullen Jennings (fluffy)" <fluffy@cisco.com>
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Cc: Christer Holmberg <christer.holmberg@ericsson.com>, mmusic <mmusic@ietf.org>, Paul Kyzivat <pkyzivat@alum.mit.edu>
Subject: Re: [MMUSIC] Bundle offer with different ports - where to expect media?
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On 23 May 2013 06:41, Cullen Jennings (fluffy) <fluffy@cisco.com> wrote:
> On May 22, 2013, at 4:55 PM, Justin Uberti <juberti@google.com> wrote:
>
>> I think we could do this using the existing syntax, e.g.
>>
>> an offer of a=group:BUNDLE A B C would indicate that the offerer would prefer A, B, and C to be muxed onto A, and
>> an answer of a=group:BUNDLE C A would indicate that the answerer is going to mux C and A onto C, and send B unbundled.
>>
>
> I suspect several people are on the fence about using this approach or the first non rejected m-line in the bundle.
>
> Can anyone think of reasons why to pick one of the other of these two approaches ?

I was originally strongly in favor of basing transport parameter
choice solely on the order of m-lines in the SDP document.

However, after our discussion this morning, if we allow a previously
rejected m-line to be revived and added to a BUNDLE group, then the
rule stating that any existing transport is used would take precedence
over this.

But that sucks.  I have a better solution for this case. We should
require that previously negotiated m-lines cannot change their BUNDLE
affiliation.  That would prevent the old m-line from being re-added to
an existing BUNGLE.  A new m-line would be required.