From: doconnor@sedona.intel.com (Dennis O'Connor)
Newsgroups: rec.video.satellite,rec.video.cable-tv
Subject: Movies and demand and digital store (was: TCI announces 500 channels)
Date: 11 Dec 92 16:27:35
Organization: Intel i960(tm) Architecture
	<MBN.92Dec11081708@greyskul.hf.intel.com>
NNTP-Posting-Host: potato.intel.com
In-reply-to: mbn@greyskul.hf.intel.com's message of Fri, 11 Dec 1992 13:17:08 GMT


Actually, having 15 minutes worth of digital store in the home
decoder box can produce a pretty-near "on-demand" movie service.

Then let's assume that the system can send video to the box faster
than needed for display ( say, 5 times faster ) and that the
box can store it till it is displayed at the regular rate.

So, you want to watch Rocky XXX. Let's assume someone else started
watching Rocky XXX, say 8 minutes ago. The cable system, on recieving
you request, starts broadcasting Rocky XXX from the beginning at
5 times the normal rate, on a dedicated channel. In 2 minutes you 
receive 10 minutes of the movie, of which you've seen 2 minutes and
8 minutes are stored in the box. But now the box (if not you) has 
caught up with where the previous viewer is in the movie, so the box
drops the high-speed channel and switches over to the other viewers
normal-speed channel for the rest of the movie. The 5X channel is
released for someone else to catch up on.

So look how the system works : two starts of the movie a minute apart
wind up using 1 normal channel for the duration and one high-speed (5X)
channel for 12 seconds. 3 1-minute-apart starts use 1 normal and 36
seconds of 5X channel. 15 minute-apart starts in a 15-minute period
use 1 normal channel and 1260 seconds ( 21 minutes ) of 5X channel.
Total equivalent normal-channel bandwidth used : 7 for the high-speed
and 1 for the normal-speed. If you had an infinite demand for the movie
and 1-minute start intervals, the total number of channels you'd
need for one movie would be the 7 channels of bandwidth for
catchup, and 1 normal channel for every 15 minutes of movie : 
15 channels total for a typical 2-hour movie.

Drop the start interval to 2 minutes and you only need 4 channels
of bandwidth (at 5x) for the catchup data. So in this scheme
you at worst for any one movie only ever need 12 normal channels
worth of bandwidth, even with infinite constant demand.

Given 240 channels worth of bandwidth (48 5X compressed channels,
or whatever) and 2-minute worst-case start intervals, 20 very
popular movies can be available for viewing. And the 15-minute
start intervals for the normal-speed channels isn't apparent
to the viewer at all : it's a function of the amount of
storage in the box, and specifies the worst-case delay between
incoming signal and the display.

If you "pause", the box would keep taking input until it's buffer
was full. Then when you un-paused, it would start displaying the
buffer, while finding a normal-speed channel less than it's buffered time
ahead of where you are ( possibly the same channel if the pause 
was short, or another channel if the pause was long ), and start
filling the buffer (possibly overwriting some previously-stored
data ) from the normal-speed channel it has re-synced to.

Rewind and Fast-Forward would do something equivalent. In the worst
case, Rewind and Fast-Forward at up to 5X would be similar to
starting the movie at an aribtrary point, which gives the
system no extra problems compared to starting at the beginning.
This means you could watch half a movie, turn off the set,
come back tomorrow and watch the rest. Or only watch some
part of a movie you wanted to.

All this might lead to movies being billed by the minute, allowing
you to save money by skipping the dull spots, or by terminating
a really awful movie early. I'd like that, but I don't know how
you'd work the royalties with the movie companies and actors
( does an actor get royalties if no one watches the parts
 of the movie the actor is in, but lots of peoplr watche the rest ? ).
A smart home box could custom-edit movies for you.

I really like this system : it would be very close to equivalent
to having your own huge library of videos in terms of convenience.








--
Dennis O'Connor			doconnor@sedona.intel.com