Subject: simple capability exchange as supported by current RTSP and SDP R FCs

From: Thomas Zeng <[email-masked]>
Date: Thu, 22 Mar 2001 18:22:55 -0800

Dear RTSP/SDP users:

Ten days ago I posted a question to this mailing list. I am glad that
Rob Lanphier, author of RFC2623, answered my question.

Here I'd like to share the answer in case you want to do such things.

If a content is in fact coded with both AMR-NB and AMR-WB, the server's
describe response would look like the
following:

     o=- 2890844256 2890842807 IN IP4 204.34.34.32
     s=I contain
     i=<more info>
     t=0 0
     c=IN IP4 0.0.0.0
     a=control:rtsp://pv.com/movie/crouching_tiger/
     m=video 8002 RTP/AVP 31
     a=control:trackID=1
     m=audio_1 8004 RTP/AVP 97
     a=rtpmap:97 AMR/8000
     a=fmtp:97 mode-set=0,2,5,7; maxframes=1
 
     a=control:trackID=2
     m=audio_2 8006  RTP/AVP 98
     a=rtpmap:98 AMR-WB/16000
     a=fmpt:98 maxframes=5
     a=control:trackID=3

This indicates that this RTSP presentation has an aggregate control
consisting of 3 streams, each with a separate
trackID.

The AMR-NB only player, upon parsing the above SDP info in DESCRIBE
response, would then select tracks 1 and 2
to do SETUP (one for each track).

A AMR-WB capable player may choose to do SETUP on tracks 1 and 3.

Any comments?

THomas

-----Original Message-----
From: Thomas Zeng [mailto:[email-masked]]
Sent: Tuesday, March 13, 2001 11:03 AM
To: [email-masked]'
Cc: [email-masked]
Subject: RE: I-D ACTION:draft-ietf-mmusic-sdp-new-01.txt

Dear RTSP/SDP users:

I have a question regarding capability exchange using SDP: 
SDP-simcap serves as a language to describe capability sets, but how does
handshaking take place during
RTSP Setup?

Say server requires AMR-WB decoder in Setup response, but the player can
only support AMR-NB (Narrow Band),
how can player signal it to server? Using another SETUP request?

Regards,
thomas zeng
packetvideo,
[email-masked]

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Thursday, March 08, 2001 3:59 AM
Cc: [email-masked]
Subject: I-D ACTION:draft-ietf-mmusic-sdp-new-01.txt

A New Internet-Draft is available from the on-line Internet-Drafts
directories.
This draft is a work item of the Multiparty Multimedia Session Control
Working Group of the IETF.

	Title		: SDP: Session Description Protocol
	Author(s)	: M. Handley, V. Jacobson, C. Perkins
	Filename	: draft-ietf-mmusic-sdp-new-01.txt
	Pages		: 35
	Date		: 07-Mar-01
	
This document defines the Session Description Protocol, SDP.
SDP is intended for describing multimedia sessions for the
purposes of session announcement, session invitation, and
other forms of multimedia session initiation.

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