Subject: Re: Sendonly in SDP

From: [email-masked]
Date: Tue, 7 Mar 2000 18:13:46 +0530

Referring appendix B.2 (bis draft) - for unicast transmission (which is
what  I guess you were asking)

For receive-only and send-or-receive streams, the port number and address
in the session description
indicate where the media stream should be sent to by the recipient of the
session description, either caller or
callee.

* For send-only streams, the address and port number have no significance
and SHOULD be set to zero.*

Regds
Arjun

--
Arjun Roychowdhury @ Hughes Software Systems

Gonzalo Camarillo <[email-masked]> on 03/07/2000
05:00:21 PM

To:   mmusic <[email-masked]>, sip <[email-masked]>
cc:

Subject:  Sendonly in SDP

Hi,

User A wants to establish a session with user B. They will have bi
directional audio.
A wants to send video to B, but A does not want to receive video from B.

A will add a parameter "a=sendonly" to its SDP. Since A does not want to
receive, A does not have to provide any local port number.

Is it correct to set the port number to 0??

m=video 0 RTP/AVP 31
a=sendonly

Thanks,

Gonzalo
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Finland

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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 07 Mar 2000 11:38:22 -0500

> and SHOULD be set to zero.*

This is true now, but we have just recently realized this is not
correct. The reason is RTCP - the SDP needs to convey the address where
the recipient can send RTCP to. As a result, I think we do need to
include an IP address and port. I think the port should be an even one
(indicating where RTP would be received on, even though no RTP will ever
be received), for consistency. RTCP would be sent to the port one
higher.

-Jonathan R.

-- 
Jonathan D. Rosenberg                       200 Executive Drive
Chief Scientist                             Suite 120 
dynamicsoft                                 West Orange, NJ 07052
[email-masked]                     FAX:   (732) 741-4778
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

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From: Gonzalo Camarillo <[email-masked]>
Date: Tue, 07 Mar 2000 18:48:59 +0200

Also about appendix B. If we want to put the other party on hold we will
set the "c" line to zero.

Shouldn't we add "a=recvonly" to indicate that we are not going to send
any packets either?

Thanks,

Gonzalo