Re: [MMUSIC] Scope of RTP payload types in BUNDLE?

Bernard Aboba <bernard_aboba@hotmail.com> Sun, 09 June 2013 17:49 UTC

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From: Bernard Aboba <bernard_aboba@hotmail.com>
To: Paul Kyzivat <pkyzivat@alum.mit.edu>
Date: Sun, 9 Jun 2013 10:48:53 -0700
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Subject: Re: [MMUSIC] Scope of RTP payload types in BUNDLE?
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Paul said: 

> There is a big difference between clipping for one second until the 183 
> is received, and clipping until the phone is answered and a 200 received.

[BA] So you're saying it is sufficient to enable media once a 183 is received, but not before?  I believe that is consistent with the current WebRTC API.   The use case document isn't clear that this is the bar that is being set, though.  

One issue is what the WebRTC gateway will do if it gets media before the 183.    If it just forwards it on, then it will be dropped by the browser until the 183 shows up and setRemoteDescription is called.  Should it buffer it until the 183 arrives?

> But I was suggesting that we couple a requirement for PRACK with BUNDLE, 
> and say that media should not be sent until the PRACK is received. So 
> then there won't be clipping at all.

[BA] Personally, I don't see PRACK as being required for BUNDLE, at least in WebRTC uses. However, a WebRTC/SIP gateway probably should support PRACK.