Subject: Re: [clue] draft-romanow-clue-framework-00

From: Paul Kyzivat <[email-masked]>
Date: Wed, 20 Jul 2011 20:04:16 -0400

(As individual)

I have what seems to me to be a fundamental question or misunderstanding 
about the approach taken where the receiver "configures" the streams to 
receive from those offered by the sender.

I see how this works in a point-to-point configuration.
But I don't see how it works with an MCU. In particular, I don't see now 
mutually exclusive capture sets are selected.

Assume that one room has a camera that zooms, and so can offer a capture 
set with it zoomed and one with it not zoomed. This can be configured 
for one or the other, once. It can't be configured for one or the other 
independently for each of the other rooms attached to the MCU. So it 
appears that the MCU must make the choice of how to configure it. But 
how does that play out for the other rooms?

It seems the MCU will have to make this configuration decision *before* 
it advertises its capture sets to the other rooms. Hence it won't be 
able to advertise both variations and so won't hear what the other rooms 
*would like*.

It appears there will be less configurability to endpoints in the MCU 
case than in the point to point case.
Am I missing something?

	Thanks,
	Paul

---

From: Andy Pepperell <[email-masked]>
Date: Thu, 21 Jul 2011 14:19:47 +0100

Hi Paul,

I'm happy to have a go at explaining how this case is covered:

 >Assume that one room has a camera that zooms, and so can offer a 
capture set with it zoomed and one with it not zoomed.

I think more precisely in this case the room could happily a capture set 
with both the zoomed and not zoomed captures - however, the simultaneous 
transmission information also supplied by that endpoint would indicate 
that both could not be provided at the same time.

The endpoint would inform the MCU of these restrictions and thereafter 
it would be up to the MCU to determine which it asked the endpoint for 
at any given time. The MCU would have the independent task of 
advertising its own media captures to other connected endpoints, and it 
could choose whether or not to mirror other endpoints' capture 
configurations / constraints to other participants. An MCU might choose 
to always request the zoomed out view, for instance, or do so based on 
the presence / absence of other multiscreen endpoints in the conference.

Hope this helps,

Andy Pepperell

On 21/07/2011 01:04, Paul Kyzivat wrote:
> (As individual)
>
> I have what seems to me to be a fundamental question or 
> misunderstanding about the approach taken where the receiver 
> "configures" the streams to receive from those offered by the sender.
>
> But I don't see how it works with an MCU. In particular, I don't see 
> now mutually exclusive capture sets are selected.
>
> Assume that one room has a camera that zooms, and so can offer a 
> capture set with it zoomed and one with it not zoomed. This can be 
> configured for one or the other, once. It can't be configured for one 
> or the other independently for each of the other rooms attached to the 
> MCU. So it appears that the MCU must make the choice of how to 
> configure it. But how does that play out for the other rooms?
>
> It seems the MCU will have to make this configuration decision 
> *before* it advertises its capture sets to the other rooms. Hence it 
> won't be able to advertise both variations and so won't hear what the 
> other rooms *would like*.
>
> _______________________________________________
> clue mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/clue

---

From: Paul Kyzivat <[email-masked]>
Date: Thu, 21 Jul 2011 09:40:30 -0400

> the presence / absence of other multiscreen endpoints in the conference.

Yes, I see it could do that.
But it seems difficult for it to do so based on the desires of the other 
endpoints. It can't easily solicit those desires because it can't 
advertise both alternatives. (If it were to do so it would open the 
possibility that one room would configure a group containing the zoomed 
view, and some other room would configure a group with the unzoomed view.)

So the MCU is left to choose on its own and then advertise only groups 
based on that choice. The other rooms then have no indication that the 
choice not taken is even a possibility.

	Thanks,
	Paul