Re: [rtcweb] Codec control and SDP offer/answer frequency

Harald Alvestrand <harald@alvestrand.no> Thu, 23 August 2012 11:22 UTC

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Date: Thu, 23 Aug 2012 13:22:33 +0200
From: Harald Alvestrand <harald@alvestrand.no>
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To: Christer Holmberg <christer.holmberg@ericsson.com>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Codec control and SDP offer/answer frequency
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Clipping to a single issue....

On 08/23/2012 01:05 PM, Christer Holmberg wrote:
> Also, you would need to describe how the data channel protocol relates to negotiating being done on the signalling plane.
>> The format of the signalling channel is defined to be outside the scope of the specification, so it's perfectly legitimate to use the data channel for that purpose - application decision!
> Sure, applications can do whatever they want.
>
> But, I think it would be good to have a standardized mechanisms which works for any application. AFAIK, that was the whole purpose of the discussion in Vancouver.
>
Since we've settled on using SDP at the UA/Application interface, 
representing the data in SDP is a valid way of describing that interface 
- thus indeed making it available for use by any application written to 
that interface.

The particular worry you raised was how fast applications can do 
offer/answers - which is dependent on how their signalling channel is 
implemented, and how many intermediate nodes have to process the data.

That's what I'm thinking will be different in the Pokerstars example 
than in a SIP-telephone-gateway example.