Subject: [AVT] Three way and Conference calls

From: Spoorthi <[email-masked]>
Date: Tue, 21 Apr 2009 14:20:13 +0530

Hi,

Plz provide info on Role of RTP/RTCP in three way and conference calls.
During a conference call, RTP mixing has to be performed by the 
endpoints or servers. Plz clarify.

Thnx and Rgs,
spoorthi

---

From: "Brian Rosen" <[email-masked]>
Date: Tue, 21 Apr 2009 13:46:34 -0400

RTP and RTPC are always used in a single end to end leg.  The mixer has a
point to point connection with each leg.  The mixer can be in an endpoint or
in a server.  If a phone, for example, can mix a three way, it may simply
have point to point RTP connections with the other two parties.  If it
can't, it may need an external mixer to do that.  That mixer would have 3
point to point RTP connections.

     B                 S
   /   \     or     /  |  \
  A     C          A   B   C

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Spoorthi
Sent: Tuesday, April 21, 2009 4:50 AM
To: [email-masked]
Subject: [AVT] Three way and Conference calls

Hi,

Thnx and Rgs,
spoorthi

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www.ietf.org/mailman/listinfo/avt

---

From: Randell Jesup <[email-masked]>
Date: Thu, 23 Apr 2009 11:45:18 -0400

>point to point RTP connections.

There's one other configuration for 3-way and conference calls:

    B
  /   \
 A --- C

I.e. a no-central-mixer solution, or an "all to all media" topology as
defined in RFC 5117.  Each endpoint would be responsible for doing it's own
mixing as needed, and the upstream and downstream bandwidth of A and C (for
the first diagram above) and A, B and C (for the second diagram) would be
roughly doubled compared to a mixer solution.  A & C (or A, B and C) also
probably need to be capable enough to decode two incoming streams, though
they could implement a hard switch behavior (instead of mixing) and only
decode one stream at a time.

This configuration isn't often used in the unicast world, I believe; it
fits better in a multicast world where the upstream bandwidth of A & C (or
A, B & C) wouldn't have to increase.  Also, as you add more participants,
the bandwidth and processing multiplication effect quickly will cause
problems. 

-- 
Randell Jesup, Worldgate (developers of the Ojo videophone), ex-Amiga OS team
[email-masked]
"The fetters imposed on liberty at home have ever been forged out of the weapons
provided for defence against real, pretended, or imaginary dangers from abroad."
		- James Madison, 4th US president (1751-1836)

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From: "Roni Even" <[email-masked]>
Date: Fri, 24 Apr 2009 10:03:52 +0300

Hi,
You should look at http://tools.ietf.org/html/rfc5117 that discuss the
different RTP topologies. 
Still you can always do a full mesh and let every endpoint mix the streams.

Roni Even

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Spoorthi
Sent: Tuesday, April 21, 2009 11:50 AM
To: [email-masked]
Subject: [AVT] Three way and Conference calls

Hi,

Thnx and Rgs,
spoorthi

---

From: Spoorthi <[email-masked]>
Date: Fri, 24 Apr 2009 15:23:54 +0530

A endpoint involved a three way call will have point to point RTP 
connections with the other two parties as shown below

*
     B    
   /   \    
  A     C       
*

Now, the endpoint the 'B' has to mix the audio received from the 
endpoint 'A' and transmit the same to endpoint 'C'.
The endpoint 'B' has to mix the audio received from the endpoint 'C' and 
transmit the same to endpoint 'A'.
To perform the mixing should the endpoint B deployed with a mixer or 
endpoint B has to do the audio mixing???
Plz clarify...

Thnx and Rgs,
spoorthi