All things related to multicast

[Hans Kuhn <>]

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

Key fingerprint =  1E BC 32 03 AC E9 82 6C  44 4A CD 63 BB 2D 51 89