Re: [MMUSIC] BUNDLE ALMOST DECISSION: BUNDLE PORT

Paul Kyzivat <pkyzivat@alum.mit.edu> Fri, 24 May 2013 14:49 UTC

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Date: Fri, 24 May 2013 10:49:15 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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Subject: Re: [MMUSIC] BUNDLE ALMOST DECISSION: BUNDLE PORT
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On 5/24/13 8:39 AM, Christer Holmberg wrote:
> Hi,
>
> At the interim yesterday, we agreed to use the SDP BUNDLE group
> attribute to indicate on which port bundled media will be sent. In an
> SDP offer, the order of the attribute mid values can be used by the
> offerer to indicate a “wish”, but the first attribute mid value in the
> answer indicates where the answerer will eventually send bundled media.

This could be interpreted to mean the first a=mid value in the SDP.
I'm sure you mean "the first mid value in the a=group:bundle" line.
Or perhaps "the first mid value in the bundle group" - assuming there is 
a definition that "bundle group" means an a=group:bundle line.

This can be "future proofed" by saying that the first mid value in the 
bundle group in the answer that references an m-line with non-zero port 
value. I realize this adds nothing unless 5888 is revised to permit 
m-lines with zero port in a bundle group. But at least it will be ready 
for that, and harms nothing.

	Thanks,
	Paul

> The main usage of this is the “initial offer”, when each m- line within
> a bundle group has a different port value.
>
> So far so good.
>
> The reason I say “almost decision” is because we have started a new
> discussion regarding updated offers, adding new m- lines etc. We need to
> make sure that the order-to-mid-values semantics also apply to those,
> and what restrictions there are when adding m- lines.
>
> But, for now, if you OBJECT to the general principle of using the SDP
> group attribute mid value order for indicating the port where media will
> be sent, please indicate so.
>
> Regards,
>
> Christer
>
>
>
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