Subject: Remote recordings

From: Miguel Chamochin <[email-masked]>
Date: Fri, 20 Jun 1997 11:04:42 +0200

I have no seen yet any RTSP exchange with a remote recording server,
where the client gives to the server the presentation description on the
fly, in order to describe the session client would like to record.

    This scene could have two differents possibilities: a) an append to
a existing session or b) the creation-overwrite of a new one.

  a) The append could fix the SDP description on the server with the
following exchange:

  C->S: DESCRIBE /test RTSP/1.0 1
        Accept: application/sdp

  S->C: RTSP/1.0 200 1 OK
        Content-Type: application/sdp
        <presentation description>

  This notice it exists in the server and allow to the client to decide
the record operation "Mode" (append-overwrite).

  b) How could we suggest to the recording server a new prentation
description ?.

   SETUP specifies the transport mechanism...

   SET_PARAMETER set the value for a presentation or stream... 

   RECORD initiates recording a range of media data according to the
presentation description (which one?).

   Do you think the best solution is send the new session description
like a header of the RECORD method, and another header named "Mode"
which specify the recording mode ?.

   It is possible SET_PARAMETER with the presentation you would like to
work...

   Mangel.

-- 
         Miguel Angel Chamochin Gomez
         Information Technology Division
         CERN   CH-1211 Geneve 23  SWITZERLAND
         Phone: +41-22-767-9703
         Fax: +41-22-767-7155
         e-mail: [email-masked]

---

From: Bruce Butterfield <[email-masked]>
Date: Fri, 20 Jun 1997 08:38:42 -0700 (PDT)

Currently, we have RECORD working between a client and the server in the
following manner:

C->S:	DESCRIBE rtsp://foo/bar RTSP/1.0 1
	Content-type: application/sdp
	Content-length: 348

	... SDP description of stream to record

S->C:	RTSP/1.0 200 1 OK

C->S:	SETUP rtsp://foo/bar RTSP/1.0 2
	Transport: rtp/udp;mode=record

S->C:	RTSP/1.0 200 2 OK
	Transport: rtp/udp;port=3244;mode=record
	Session: 508876

C->S:	RECORD rtsp://foo/bar RTSP/1.0 3
	Session: 508876
	Range: 0:0-40778:3221
...

The DESCRIBE contaning a stream description tells the server that it needs to
anticipate an impending RECORD session, and to cache the stream description of
the URL. The client sends a SETUP with the paramter 'mode=record'. In the
setup response the server returns a session id and the port to send data
packets to (the reverse of PLAY, in which the client requests a particular
port). The client then sends a RECORD message, waits for an OK response from
the server, and begins sending packets. 

Bruce Butterfield <[email-masked]>  	Phone: (206) 674-2467
Progressive Networks			Fax:   (206) 674-3580
Software Development Engineer - Platform Group