Re: [MMUSIC] FWD: I-D ACTION:draft-even-mmusic-video-media-contr ol-00.txt

[Jonathan Rosenberg <jdrosen@dynamicsoft.com>]

inline.

Even, Roni wrote:
> Hi Joerg,
> Thanks for your comments.
> 
> 1. About the BNF I will fix it.
> 
> 2. I thought of having a section describing the usage in SIP and SAP but
> noticed that other drafts like offer/answer and simple capabilities do
> not
> have section about SIP usage. If you meant that you want to explain how
> the
> encoder uses this attribute to select the mode of operation I can add
> this
> 
> 3. About fast update and freeze. 
> 	3.1 Using RTCP feedback for update was discussed in the last
> meeting
> and I agreed with the AVT guys that this should not be there
> 	3.2 I would like to look at the new picture and freeze picture
> in
> the same context as a new codec request. This means that we use
> signalling
> to ask for a new codec and I see this feature as the same since I am
> asking
> for the same codec but with a new picture. If you want to look at it
> from
> the decoder wants a new codec or a new picture. Since changing a codec
> during a session is working in SAP and in SIP I do not see the problem

THe problem is that the new picture request, in particular, is not a 
change in STATE of the session, its a command to send a new picture. The 
SDP and offer/answer stuff is appropriate where there is a change in 
state of the session parameters. That is not the case here. I also 
suspect latency is an issue, since the video is distorted until you get 
the new intra picture. So it would seem to argue for a media path thing. 
Latency is generally not an issue for things like codec change and hold.

The new picture request is a lot like things such as camera controls, 
which are real-time media stream control activities. I am inclined to 
argue that the appropriate solution is an e2e control protocol that, 
like a media stream, is signaled in the SDP. We've argued that the same 
is true for thigns like floor control.

Freeze picture request does seem like its a lot like hold. Its a 
persistent state of the session, and it must be explicitly changed to 
get off of "freeze". Thus, I think an SDP approach here is fine.

-Jonathan R.



-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue
Chief Scientist                         First Floor
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