[commedia] does anyone know of

[Ade]

technical feasibility = tenuous

That must be some compression algorithm to get a 90 minute movie to download
in 2 minutes over a copper wire phone line!
If he is referring to a T1 style broadband connection however, it may be
feasible, although it would still be a vast improvement on regular
compression. As a guide a 90 minute PAL size video compressed using a LSX
(DVD style MPEG) algorithm produced in Adobe Premier (for example) is about
1.5Gb (1500Mb) in size, a standard analogue modem (56k) will download at an
average of 5k per second (actually more like 3.5 to 4k taking into account
line noise) working this out VERY roughly (assuming 4k speed) gives us a
download time of 384000 seconds (or 6400 minutes, or 107 hours!!!). A basic
broadband connection has speeds approaching 20k to 40k per second (basic
ADSL etc... or NTL style cable), with more expensive options reaching 128k.
T1 averages about 256k but can reach 512k or higher (slow LAN speeds). Your
typical mobile phone achieves about 1.5k but newer technologies give you
more normal speeds. Even with a T1 connection it's still going to take about
an hour. I'm working on the assumption that the video is normal TV quality,
you could compress this even further by using a smaller screen size, lower
the algorithm quality, use a more efficient algorithm such as DivX, and so
on, but he specifically stated broadcast quality or at least VHS.

(as an aside if ANYONE watches ITV digital, you can see cheap MPEG
compression in action by looking closely at the players in the football
matches, a small pixelated area follows them around when you get a wide
angle camera view)

Now if he is talking about a streaming video which is downloaded and played
in real time - with a slight start delay - then this is feasible even with
normal technologies, in fact we are already doing this and have been for a
few years. However, why you would want to sit and wait for a 90 minute video
to download on a mobile phone is beyond me. I have made an assumption here
that we are talking about mobile comms, if we are referring to a video booth
kind of thing then again the best connection is T1 or equivalent so it
brings us back to the above math.

We Brits though have to be envious of our rebellious cousins as broadband
connections are pretty standard fare for most interent users over there, and
they rarely have to pay the same kind of charges as we do (in some cases the
connections are free). Consequently there attitude is very blase where speed
is concerned.

Hope this is of some help.

Ade (the funkyfish collective)

-----Original Message-----
From: cma-l-admin at commedia.org.uk [mailto:cma-l-admin at commedia.org.uk]On
Behalf Of j.devine
Sent: 13 March 2002 14:19
To: cma-l at commedia.org.uk
Subject: [commedia] does anyone know of


++++ CMA DISCUSSION LIST ++++


Have just been put in the way of some new technology by a visiting
American(well a Brit.expat actually),and am trying to decide whether his
proposed deal is another case of
transatlantic bragging or is for real,can anyone help ,have you heard of
this and is it technically feasible /joe devine
Quote: from friend:-
We think what the vi-phone basically is is a way of compressing a video
signal so that it can be sent down a telephone [copper wire] line. and it
is unpacked at the other end so as to be able to display a clear video
picture. I suspect that that is what the vi-phone is.We think what the
vi-phone basically is a way of compressing a video signal so that it can be
sent down a telephone [copper wire] line. and it is unpacked at the other
end so as to be able to display a clear video picture. I suspect that that
is what the vi-phone is.

People will get their stuff to us, though, in many ways, including
e-mailing video-tapes (with this system, a 90-minute movie downloads in 2
minutes, and begins playing before it's finished arriving!








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