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From: peter@taronga.hackercorp.com (Peter da Silva)
Newsgroups: comp.dcom.telecom
Subject: Re: Videos By Phone
Message-ID: <16463@accuvax.nwu.edu>
Date: 27 Jan 91 18:34:38 GMT
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X-Telecom-Digest: Volume 11, Issue 71, Message 4 of 7


> Reportedly, the technology can transmit a two hour movie over phone
> lines in fifteen seconds to thousands of destinations. That must be
> something like 20-40 gigabits/s transmission (and to think people get
> excited over such primitive toys as ISDN or mere 56 kb/s stuff :->).

Begin back-of-the-envelope mode...

Let's see, assuming they're using something like JPEG and a moderate
resolution video signal (640x400x12 bits). That's 380K per frame, 30
frames per second, and the high side of 20:1 compression ratio. Give
them 30:1 to make the calculations easy. About 2.5 gigabytes in 15
seconds, or a little over 1 gigabit/second. You couldn't do it over
ethernet. You'd have to run fiber into each house...

Hey, if they pay for the fiber it sounds like a good deal. :->


(peter@taronga.uucp.ferranti.com)