Subject: [mediactrl] draft-boulton-sip-control-framework-00

From: "Robert Hagens" <[email-masked]>
Date: Fri, 27 Jan 2006 22:16:08 GMT

<span style='font-size:10.0pt;
font-family:Arial'>Greetings,

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<span style='font-size:10.0pt;
font-family:Arial'>I am investigating the use of SIP and a control protocol for
management of media. The basic functions I need are typical VCR-like control
(play/pause/…) but I also will need other primitives (like camera
control). I have been working through scenarios of how to use SIP to negotiate
the SDP, in which one media is a control channel which in turn runs RTSP.

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<span style='font-size:10.0pt;
font-family:Arial'>It occurs to me that one could use this framework to base a
control package to accomplish the VCR-like control. RTSP-lite anyone?

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<span style='font-size:10.0pt;
font-family:Arial'>My question is, has anyone thought about how such a control
package might relate to a protocol like RTSP? 

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<span style='font-size:10.0pt;
font-family:Arial'>In particular, I appreciate the section relating this to
COMEDIA and the potential that an external server may initiate the TCP
connection. I think this will help in a wide variety of NAT scenarios (for
example, if the media server is behind a NAT). One item that I am thinking
through is how this might work in practice. If the client sends in its SDP (a=setup:passive<CRLF>a=connection:new),
and subsequently the server initiates the control connection back to the
client, how is the client to identify which server initiated the TCP connection
(assume it was setting two of these up in parallel)?

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<span style='font-size:10.0pt;
font-family:Arial'>Thanks in advance for any thoughts on this…

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<span style='font-size:10.0pt;
font-family:Arial'>Rob Hagens

<span style='font-size:10.0pt;
font-family:Arial'>Envysion

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