Subject: [AVT] Different sessions, different SSRC

From: "Michael Hakimi" <[email-masked]>
Date: Wed, 12 Mar 2008 16:54:03 +0200

Hi,

As I the RFC describing the RTP says, different sessions should have
different SSRCs.
If so, I have a simple question. Let us have a scenario with two endpoints
having two sessions each. One of the sessions is a P2P session, and the
other is a conference (the two endpoints participate in the conference).
Each of the two endpoints will receive two RTP streams with different
SSRCs containing the same media (lets say voice). An endpoint cannot
distinguish between the two streams and know that it is actually the same
voice. The two streams will be played and an echo will be heard.
This problem get worse when we have more than two streams.

Is there any way to avoid this problem?

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

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From: Randell Jesup <[email-masked]>
Date: Wed, 12 Mar 2008 11:16:43 -0400

>Is there any way to avoid this problem?

Basically: not necessarily - the conference (a single connection to an MCU/
conferencing server) may have a mixture of streams in the RTP session.
You may be able to identify the "duplicate" packets from SSRC and RTCP
SDES/etc.  However, there may be no "duplicate" - the conference system
may well be a mixer that combines them and generates a new stream, etc.

See the avt-topologies draft, among others.

-- 
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
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