Re: [Sipping] Conference speaker control

[David R Oran <[e-mail]>]

On Dec 4, 2004, at 9:04 AM, Even, Roni wrote:

> Magnus,
> The whole discussion is about the SIP conference package that suggests
> that a SIP user will know the source of the stream based on SSRC. So if
> there are media sessions that are not RTP is a SIP call then SSRC does
> not work.
> Roni
>
While this is strictly true, that's not the point. The point is whether  
the conferencing work ought to rely on a "correlator" in or associated  
with the media stream, and have arrivals on the media stream trigger  
any UI behavior, in order to identify the  
source(s)/speakers/arm-wavers/typers/gas-emitters.

I believe it should. In the case of RTP, this is the SSRC or the CNAME  
or both.

If the conferencing system wishes to accommodate a media session  
without this identification capability there has to be some way to do  
the correlation. I'm suggesting that emulating the media session by  
actually always having one to the UA is a good way to do this rather  
than sending speaker identification messages in realtime over the  
conferencing control protocols.

What do others think? This is important enough that other folks ought  
to weigh in here.

Dave.

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]] On
> Behalf Of Magnus Westerlund
> Sent: Friday, December 03, 2004 11:11 AM
> To: Even, Roni
> Cc: sipping; David R Oran
> Subject: Re: [Sipping] Conference speaker control
>
> Even, Roni wrote:
>> Hi,
>> This is from the comedia draft, is it RTP, it does not say so.
>>
>>            m=image 54111 TCP t38
>>            c=IN IP4 192.0.2.2
>>            a=setup:passive
>>            a=connection:new
>>
>> Roni
>
> No, that is clearly T38 over TCP which has a mode that is not RTP,
> however if you look in the RTP over TCP draft:
> http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-framing- 
> contrans-
> 03.txt
>
> You can find the following SDP:
> v=0
> o=first 2520644554 2838152170 IN IP4 first.example.net
> s=Example
> t=0 0
> c=IN IP4 192.0.2.105
> m=audio 9 TCP/RTP/AVP 11
> a=setup:active
> a=connid:1
>
> It is also this draft that register the RTP over TCP SDP protocol
> identifier.
>
>
> Cheers
>
> Magnus Westerlund
>
> Multimedia Technologies, Ericsson Research EAB/TVA/A
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> _______________________________________________
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David R. Oran
Cisco Fellow
Cisco Systems
7 Ladyslipper Lane
Acton, MA 01720 USA
Tel: [phone]
Email: [e-mail]


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