Subject: [AVT] Video conference question

From: "Krishna Prasad Kalluri" <[email-masked]>
Date: Sat, 2 Aug 2008 23:42:54 +0200

Hello,

I would like to understand different kinds of video conferencing
scenarios. In a video conference the video can be mixed or switched or
some thing else?. I am looking for a document pointer if any to
understand the differences. Different sources pointed below have
provided some information. But I am specifically interested about
RTP/RTCP behavior in a video conference.

Regards
Krishna

Background:

I would like to understand the relation between mixing and conferencing.
I don't think they are interchangeable terms.

My understanding is mixing is one way to achieve a conferencing. So I
consider conferencing to be a super set. Mixing is one operation
depending on the media type.
I would like to understand this to know the RTP/RTCP behavior if media
is carried with RTP. If there is a messaging conference with MSRP that
is not mixing. 

RFC 3550 defines the concept of mixing and it describes RTP and RTCP
behavior. So if we say some thing is mixing I would like to see the
implementation of RTP and RTCP is according to RFC 3550. 

In Section 4.1 of RFC 4597 there is some information about video mixing
scenario. So this can be treated as mixing according to RFC 3550.
In section 4.2 of RFC 4597 there is a video conferencing scenario. I
guess this is not a mixing.

http://tools.ietf.org/html/draft-ietf-mediactrl-mixer-control-package-00
defines video-layout and video-switch. I think video-layout is mixing
and video-switch is not mixing.

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

---

From: Colin Perkins <[email-masked]>
Date: Sat, 2 Aug 2008 23:24:26 +0100

Take a look at RFC 5117 for a discussion of various possibilities.

Colin

On 2 Aug 2008, at 22:42, Krishna Prasad Kalluri wrote:

> scenarios. In a video conference the video can be mixed or switched  
> or some thing else?. I am looking for a document pointer if any to  
> I would like to understand the relation between mixing and  
> conferencing. I don't think they are interchangeable terms.
>
> My understanding is mixing is one way to achieve a conferencing. So  
> I consider conferencing to be a super set. Mixing is one operation  
> I would like to understand this to know the RTP/RTCP behavior if  
> media is carried with RTP. If there is a messaging conference with  
> MSRP that is not mixing.
>
> RFC 3550 defines the concept of mixing and it describes RTP and  
> RTCP behavior. So if we say some thing is mixing I would like to  
> see the implementation of RTP and RTCP is according to RFC 3550.
>
> In Section 4.1 of RFC 4597 there is some information about video  
> mixing scenario. So this can be treated as mixing according to RFC  
> 3550.
>
> In section 4.2 of RFC 4597 there is a video conferencing scenario.  
> I guess this is not a mixing.
>
> http://tools.ietf.org/html/draft-ietf-mediactrl-mixer-control- 
> package-00 defines video-layout and video-switch. I think video- 
> layout is mixing and video-switch is not mixing.
>
>

-- 
Colin Perkins
http://csperkins.org/