[opendtv] Re: The End of TV as We Know It

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Mon, 13 Dec 2004 12:55:00 -0500

At 12:24 PM -0500 12/13/04, Manfredi, Albert E wrote:
>But as I already said, what you achieve with this approach
>is *not* VOD, as he stated, but rather something like NVOD.
>You join a pre-existing stream, you don't start from the
>top. To get real VOD, you need unicast sessions between
>subscribers and servers. This would be an expensive
>proposition. It either requires lots of distributed servers
>or it requires fewer but faster servers, and lots of
>network bandwidth.

Now we are getting closer to the point.

What we have been talking about is neither VOD nor NVOD. As you 
correctly state, it is simply joining an IP multicast. But VOD is 
very much a consideration, since it is essentially a unicast service 
(NVOD can be delivered easily as a multicast since all viewers get 
the same packets at the same time). It may be possible to create very 
small IP Multicast groups for VOD by introducing small start time 
delays so that multiple viewers can be put into a group. And as I 
mentioned in another post, you might put popular content into a 
neighborhood server, where VOD services could be originated.

The whole point of this exercise, versus the current approach that 
delivers every channel to every neighborhood using MPEG-2 transport, 
is that you do not need to waste bandwidth for channels that are not 
being viewed in any particular neighborhood. The net result is that 
you free up bandwidth for more VOD streams and IP data delivery to 
that neighborhood.

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