Although you can build useful Interfaces to current Web based on 28.8 kbaud and other modems using POTS (Plain Old Telephone Service) --
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Especially if you use caching as described later
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ISDN or ATM is needed for quality video delivery
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Note full screen NTSC video requires about 1.5 megabits/second to deliver if compressed with MPEG and 0.7 gigabytes of storage for each hour of material
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Compare Quad speed CDROM at 0.6 megabits/second.
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Of course today get 56 kbaud to T3 lines with older/more expensive technologies
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ISDN is 10% of needed performance but perhaps only need quarter screen with 15 frames per second for education as typically uses few minutes clips -- you are not watching 2 hour movie
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Further improved compression such as Wavelets makes ISDN even more attractive -- unfortunately MPEG is standard and will be built into PC's
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