Subject: Re: PROGRESS: RTSP URL issues

From: Rob Lanphier <[email-masked]>
Date: Sun, 27 Jul 1997 17:58:46 -0700

Actually, it may be helpful to describe what exactly we envision occuring
with a CGI interface:

1.  Client sends query string as part of RTSP DESCRIBE URL.  This allows
the server to set up the environment exactly as it would be done for an
HTTP script (setting proper environment variables and such).

2.  The script uses the query to potentially generate a file to stream
(such as an audio/video container).  It may be the case that this video
isn't stored anywhere (i.e. it's generated on the fly, similar to how the
GD library currently generates gifs).

3.  The script sends the file to standard output, just as it would if this
were HTTP CGI.  Rather than directly sending this script to the contents of
a reply, as it would in HTTP, the RTSP server stashes it away into a
temporary file.

4.  This newly created file (which may contain multiple substreams) is now
a resource that an RTSP client can SETUP and PLAY.

Since the current CGI interface doesn't make it possible to "pass back" the
URL, we would have to make a new CGI-like interface in order to make this
possible with stream ids too tightly embedded in the URLs.   Either taking
stream ids out of the URL, or devising a clean deterministic way of
extracting the stream id out of the URL is the only way that this is going
to be possible.

Rob

---
Rob Lanphier               Voice: (206)674-2322         Fax: (206)674-2699
Program Manager-Protocols                         Email: [email-masked]
Progressive Networks-Home of RealAudio            Web: http://www.real.com
For more information on firewalls:       http://www.real.com/firewall.html
For more information on RTSP:               http://www.real.com/prognet/rt