Re: [MMUSIC] Thoughts on m= lines and media streams

Adam,

thanks for analysing the various proposals and putting the draft together.
>From a quick read I have some issues with backward compatibility of your proposal to include 
"common" attributes only in the first m-section.
Assuming that the examples in the draft are offers, an answerer that
didn't implement any of the mechanisms would probably show the
following behavior.  

Alternativ 1a and 2 have ICE candidates only for the first m-section.
An answerer that doesn't understand the grouping semantics could -
dependent on the network topology - end up having audio, but no video
connectivity.  
With having other attributes only in the first m-section we could get other issues.

Alternative 1b doesn't have this problem, but the offer would most likely
be rejected resulting in no media at all. 
I preferred the original mmt proposal as it had additional m-sections,
that could be accepted by a legacy answerer without the need for a GW that performs complex SDP operations.

Regards
Thomas

Adam Roach wrote:
> Based on the conversations we've had so far, I've put together the
> following summary of my thoughts on the topic of whether we
> want to put
> multiple media streams in a single m= line.
> 
> http://www.ietf.org/id/draft-roach-mmusic-mlines-00.txt
> 
> Sorry for the relatively short lead time before next week's
> meeting -- I
> had meant to put this kind of summary together a week or two ago, but
> have been far busier than I anticipated.
> 
> /a
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