All things related to multicast

[Hans Kuhn <>]

Marshall,

Yes, guide.tvg includes information from SAP >if< you turn
on the SAP listener, but the main benefit is for programs
that you created on your content manager for your own
administrative domain.

I understand the direction you are going with this, i.e. the
content manager model doesn't solve the interdomain
advertisement issue unless you have a central server that
everyone shares. I merely disagree with you as to the
necessity of a central authority for all content available
on the net.

BTW, the IP/TV client does address the interdomain issue in
a manner I find satisfactory, which is that you can define
numerous content managers in your client, thus allowing you
to select video and audio from the content providers that
you find interesting.

Discovering content providers is an exercise left to the
reader. My guess is that it involves money and lots of
it. ;)

Hans

On Tue, 13 Aug 2002, Marshall Eubanks wrote:

:    Hans;
:    
:        Thanks for the info. Is there a specified means for putting SDP into 
:    the guide.tvg ? I always thought that this was based on our SAP 
:    announcements :)
:    
:    Marshall
:    
:    Hans Kuhn wrote:
:    
:    > Correct. MacTV simply grabs the guide.tvg file from any
:    > IP/TV content manager. Mind you, if a content manager is not
:    > available, then MacTV and IP/TV have a built-in SAP
:    > listener that you can turn on to gather SDP files.
:    > 
:    > On Tue, 13 Aug 2002, Marshall Eubanks wrote:
:    > 
:    > :    Dear Hans;
:    > :    
:    > :    Is this what MacTV does ?
:    > :    
:    > :    Hans Kuhn wrote:
:    > :    
:    > :    > Marshall,
:    > :    > :    > IP/TV uses a fairly elegant solution. Clients and servers
:    > :    > alike do an HTTP get for the following file:
:    > :    > :    >   http://iptvhost.uoregon.edu/iptvfiles/guide.tvg 
:    > :    > :    > (go ahead, take a look. I'll wait.)
:    > :    > :    > For those who didn't look, it's basically a bunch of SDP
:    > :    > files concatenated together.
:    > :    > :    > The client simply parses this file and displays the 
contents
:    > :    > to the user. When a user joins a session, the player refers
:    > :    > back to the guide.tvg file to get the group and port, (and
:    > :    > source for SSM).
:    > :    > :    > The server looks for it's IP address in the guide.tvg 
file
:    > :    > and if it finds a reference to itself, it starts sourcing
:    > :    > the stream according to the information found in the
:    > :    > corresponding SDP file from the guide.tvg file. clever.
:    > :    > :    
:    > :    
:    > :    So if I put (spoof) your  IP address in one of my SDP's I could 
force
:    > :    one of your machines to start broadcasting ?
:    > :    
:    > :    
:    > :    > I have a piece of semi-working code that someone here at the
:    > :    > UO wrote to take the current guide.tvg file and create a web
:    > :    > page with links you can click on to launch a session with
:    > :    > the client of your choice. NO SAP REQUIRED.
:    > :    > :    > I also believe the IP/TV content manager v3.4 includes a 
web
:    > :    > page that does a similar function, tho the formatting is not
:    > :    > customizable and thus not very interesting to marketing
:    > :    > types who like to create web pages with their company logo
:    > :    > on it.
:    > :    > :    > Did I answer your question?
:    > :    > :    
:    > :    
:    > :    Not quite. I figured we could reverse engineer what IPTV does, 
what
:    > :    I was really asking was, can we use the results of that reverse
:    > :    engineering ?
:    > :    
:    > :    Marshall
:    > :    
:    > :    
:    > :    > Hans
:    > :    > :    > On Tue, 13 Aug 2002, Marshall Eubanks wrote:
:    > :    > :    > :    
:    > :    > :    
:    > :    > :    John Zwiebel wrote:
:    > :    > :    
:    > :    > :    > On 8/7/02 9:43 AM, "Alan Crosswell" 
<>
 wrote:
:    > :    > :    > :    > :    >>A WWW-based guide is UNICAST.  Bah!
:    > :    > :    >>/a
:    > :    > :    >>
:    > :    > :    >>
:    > :    > :    >>
:    > :    > :    > :    > But it provides the information quickly so 
receives
:    > :    > :    >  know which source to join to.  Why multicast information
:    > :    > :    >  about millions of sources using up network BW when that
:    > :    > :    >  same info can be stored on a disk and retrieved in just
:    > :    > :    >  a few seconds?
:    > :    > :    > :    > FWIW, it "sounds like" you think the SDR/SAP 
application
:    > :    > :    >  is a "good thing". I believe it is very, very broken.
:    > :    > :    >  (And I do mean the application not the protocols)
:    > :    > :    > :    > Look at how the IP/TV content manager works.  You 
get the
:    > :    > :    >  info you need, when you need it because you specifically
:    > :    > :    >  ask for it.  No waiting for an SDR packet to "finally"
:    > :    > :    >  show up.
:    > :    > :    > :    > :    
:    > :    > :    
:    > :    > :    And is there a published and available protocol describing 
how this works ?
:    > :    > :    
:    > :    > :    
:    > :    > :    
:    > :    > :    
:    > :    > :    > :    
:    > :    
:    > :    
:    > 
:    > 
:    
:    
:    

-- 
Hans Kuhn, Academic User Services            office (541) 346-1714
University of Oregon, 237 CC                 fax    (541) 346-4397

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