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The promise of DVD

© Anne Kellerman

If your local food or convenience store stocks the top hundred movies on Divx, then buying a Divx disc on impulse, along with soda and broccoli, is handier than renting a VCR tape. They cost about the same, but you can just throw the disc away after using it, whereas you would have to return the tape. However, if you need to order discs by mail or even by way of the Internet, then you will probably just drive down and rent a tape instead. Another drawback of Divx is that surprisingly many people watch a particular type of video content for which they might not want a company to keep a record of their viewing habits.

There is also a real question of whether consumers are interested in higher video quality. S-VHS and Hi-8 tapes that give about 400 lines of horizontal resolution have been available for years, but no video rental market has ever developed for them and S-video players account for a small part of the sales of all VCRs.

The last major reason why DVD may not replace VCR tapes is that, today, you can't record on a DVD. Thus, you would still need a VCR for time-shifting and building a personal-use library of favorite broadcasts. Fortunately, writable forms of DVD are in the works. Unfortunately, several competing writable forms will delay adoption of a standard, and fear of obsolescence will discourage consumers from purchasing machines that write any one standard. Writable DVDs are queued up to replay the VHS-vs.-Beta disaster movie.

So how about DVDs' promise to replace CD-ROMs for distributing computer programs and multimedia content? Whereas a CD-ROM can contain "only" about 0.5 GB, a DVD can contain 4.7 GB (that is an amazing 4,700 MB or 4.7 times ten to the ninth bytes) on one side and one layer, or 8.5 GB on one side with two layers, or even, if you are willing to turn the disc over or use a more expensive player that has a head on each side of the disc, 17 GB on two sides and two layers. Again, note that information is what costs money. Thus, there is little difference between the cost of a DVD and a CD-ROM, if they contain the same information. Moreover, the cost of including a DVD drive (which can read CD-ROMs as well) in a new computer is negligibly higher than the cost for a CD-ROM drive. Any evident price increment probably relates to the video decompression card that a DVD drive needs in order to play back compressed movies, but not to load software.