t the dawn of the 1990s, cable industry executives enthused about the coming age of digital cable. In the future, they proclaimed, cable subscribers will have 500 channels to choose from.
Today, the folly of those dreams is becoming all too clear. Future cable subscribers won't need 500 channels to choose from, they will need precisely one channel: the Internet. And on that single channel, viewers will be able to display whatever they wish to see.
There are lots of ways to watch video on your home PC today. The easiest, and probably the least interesting, is to buy a video card that has a built-in television tuner, such as the ATI's All In Wonder video card. These cards let you display the TV signal either in a little window on your desktop or on the full screen of your computer monitor.
Another way to watch video on your home computer is to buy a DVD player, and then rent or purchase a digital video disc. A few months ago, my wife and I sat around my computer's 17-inch monitor while we watched a DVD of the movie ''The Matrix.''
Romantic it wasn't. Fortunately, newer computer systems now have S-Video outputs, so you can play the DVD on a conventional home theater TV system.
Compared with either of these two approaches, techniques for watching video pulled down from the Internet are still in their infancy. Called ''streaming video,'' these systems require a fast Internet connection, some special software, and a fairly fast computer. But if you have a cable modem or a fast DSL connection, there's already a world of video waiting for you on line.
News clips are the most ubiquitous form of video on the Internet. CNN's Web site (www.cnn.com), for instance, has a little section at the bottom labeled ''Video on Demand.'' When I checked it this week, it had a three-minute segment about television advertisements that the presidential candidates were running. CNN also has put its 24-part series about the Cold War on line (cnn.com/coldwar).
For movies, check out Kanakaris Communications (kkrs.net). The company has put 223 full-length movies on line. Most of them are old movies that you never would voluntarily rent from a video store - such as ''They Came From Beyond Space,'' the 1967 sleeper starring Robert Hutton and Jennifer Jayne, or the 1959 production of ''Hercules,'' starring Steve Reeves. On the other hand, there are some classics available, such as ''The 39 Steps'' and ''Dressed to Kill.''
Today, all of Kanakaris's movies are free, uncut, and advertisement-free. Eventually, though, the company hopes to make money by selling access to movies and books.
Customers might pay for a single viewing, pay per minute, or pay for unlimited access.
Or customers might subscribe to an unlimited service: as many movies as you can watch, any time you want to watch them, for a monthly fee.
Another source of free movies is Yahoo's Broadcast.com. Alas, its selection is even more limited than the one at Kanakaris. For instance, there are just three movies in the science fiction category: ''Giant Gila Monster'' (1959), ''Killers From Space'' (1954), and ''Phantom From Space'' (1953).
One problem with both Kanakaris and Broadcast.com is that you only can view the movies if you have a Windows-based PC. That's because the company only makes its movies available in the Windows Media Format, which plays only on the Windows Media Player. This is a compression technology developed by Microsoft. Although the Windows format has good video and CD-quality sound, it locks both providers and subscribers into Microsoft's Windows technology.
Beyond the Microsoft system, there are several other formats in use, including Apple's QuickTime and Real Networks's RealVideo. All of these systems rely on complicated mathematics to take the video signal and compress it into something that can be transmitted over the Internet. The program that you run on your home computer then takes the compressed video stream and displays it on your screen.
Several factors determine just how good the video signal will look, the biggest being the speed of your Internet connection. Full-motion video requires anywhere from 4 million to 10 million bits of information per second. With compression, it is possible to shrink the bandwidth requirements to between 500,000 bits and 2 million bits of information per second. Alas, most cable modems can deliver little more than 300 kilobits of information, and by the time you factor in other Internet delays, you're lucky if you can get 80 kilobits per second.
On-line movie sites deal with the bandwidth limitation by turning down the quality and shrinking the size of the video signal. Watch a news clip or a movie on the Internet, and you're likely to be sitting a few inches from your screen, staring at a box that's roughly the size of a floppy disk. The image is sure to get bigger over time as people get faster Internet connections, as well as the faster computers necessary to display full-screen video.
Although I'm sad to admit it, Microsoft's standard generally looks and sounds better than the competition's. But that advantage is likely to diminish over time, both as the competition develops better algorithms and as faster Internet connections make the differences less important.
Unfortunately, once higher-quality movies are available on line, they probably won't be free. So if you have a high-speed connection, there's no time like the present to start catching up on these 30- to 40-year-old flicks.
Technology Columnist Simson Garfinkel can be reached at http://chat.simson.net/
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