[MMUSIC] [mmusic-t140-usage-data-channel]: "a=dcsa" for T.140 cps parameter

"Schwarz, Albrecht (Albrecht)" <albrecht.schwarz@alcatel-lucent.com> Tue, 06 October 2015 08:15 UTC

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From: "Schwarz, Albrecht (Albrecht)" <albrecht.schwarz@alcatel-lucent.com>
To: "mmusic@ietf.org" <mmusic@ietf.org>
Thread-Topic: [mmusic-t140-usage-data-channel]: "a=dcsa" for T.140 cps parameter
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Date: Tue, 06 Oct 2015 08:15:13 +0000
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Subject: [MMUSIC] [mmusic-t140-usage-data-channel]: "a=dcsa" for T.140 cps parameter
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Dear All,

the discussion about "SDP limitations" at SLIM (see
https://mailarchive.ietf.org/arch/msg/slim/C-82-NRgfR50mVTkM_wklrKw0SY )
spotted an issue in draft-schwarz-mmusic-t140-usage-data-channel-02.txt
related dcsa usage:

We've used (in clause Example SDP Negotiation)
	a=dcsa:1 cps=30
which misses the fmtp parameter (see RFC 4103).

It was proposed to use instead e.g.
	a=dcsa:1 fmtp:- cps=30

The reason why we omitted the fmtp parameter is the fact that the binding is already provided by the dcsa stream-id value, hence fmtp is not required, just introduces redundancy.

However, we will update the example as suggested by Christian due to consistency reasons with draft-ietf-mmusic-data-channel-sdpneg:
   dcsa-value      = stream-id SP attribute
   attribute       = <from-RFC4566>

Any further comments?