DVD standards have been a source of contention for the past 4 years, and the battle rages on. Most people agree that the writable and the rewritable versions of the format will be primary, yet they dispute how to establish standards for those formats. The DVD Forum, an industry consortium based in Tokyo, has grappled with standards issues but has so far failed to resolve them.

DVDs can pack data tracks tightly together and can hold up to 8 hours of video. Although the DVD specification requires that players and drives read dual-layer discs, you must still flip dual-sided DVDs because no players are yet capable of reading both sides.

Vendor opinions differ widely about what the optimal version of DVD will be for the evolving market. And CD-ROMs are still strong in entertainment and business storage applications. Although DVDs offer larger capacities, CD-ROMs benefit from lower prices for both drives and media. As data storage needs grow and software program sizes escalate, DVD-ROM drives will be much more commonplace in computers.

Proponents of DVD technology predict that 170 million consumer DVD video players and DVD-ROM drives will be in use in computers by the end of 2001. Although the predicted numbers might be high, it's fairly clear that DVDs are here to stay and that they have gained critical mass. Several versions of writable DVD are either already on the market or soon to be released. To clarify their differences, I've listed the major formats below:

  • DVD-ROM offers a read-only format. Burned once by movie and game distributors, DVD-ROMs run on home entertainment systems and PCs, Moving Pictures Experts Group (MPEG)-2 devices, and drivers. This format holds 4.76GB and is the earliest version of DVD. Considered by some people simply to be larger, faster CD-ROMS, DVD-ROMs take advantage of the high-quality video and multichannel audio capabilities that manufacturers are adding to computers that come equipped with DVD-ROM. When you use them with computers, you'll find that the bigger the cache (memory buffer), the faster the DVD-ROM can supply data to the computer—a capability used more for data than video.

  • DVD-RAM is a rewritable DVD phase-change recording layer format that allows more than 100,000 rewrites. It comes in internal and external units in a range of interfaces. DVD-RAM is available as a bare disc, a single-sided disc in a removable cartridge, or a dual-sided disc in a permanent cartridge. It's a great medium for system backups.

  • DVD-R is a record-once writable format. You can create a master DVD and use it to be read from and to record to another disk. The format is used to author and test DVD titles and for some DVD publishing. Split into two versions early in 2000, the authoring version (which can be used for a master copy or for write-once applications) is intended for professional development. The general version uses a 650 nanometer (nm) laser for future ability to write DVD-RAM and is intended for home use.

  • DVD-RW is a version of the DVD-R format that uses a rewritable phase-change recording layer. It promises backward compatibility—although some players perceive it as a dual-layer disc. Designed as an authoring tool, DVD-RW accepts more than 1000 rewrites and holds up to 4.7GB per side.

  • DVD+RW—a rewritable format on the drawing boards now—is the child of Sony, Philips, Hewlett-Packard (HP), Mitsubishi Chemical Ricoh, and Yamaha. Although similar to CD-RW, it will be used as a sequential medium or as a random-access storage device. It holds 3GB per side and will allow more than 100,000 rewrites, which will make it valuable for vertical applications and local storage.

    The biggest problem in the near future is that none of the writable formats is fully compatible with the others or with existing drives and players. Until standards are worked out, incompatibility will continue to be a problem. One step in the right direction is the DVD Forum's DVD Multi logo, whose presence will guarantee compatibility with DVD-R, DVD-RW, and DVD-RAM. A Multi player will be able to read all three formats, and a DVD Multi recorder will be able to record using all three.

    Analysts predicted that DVD would take off at unheard-of speeds—and, in fact, it has sold faster than videotape, CD-ROM, and laser disc. And in terms of revenue per unit sold, DVD has become the most successful consumer electronics entertainment product ever produced. If industry members work together to merge some of the DVD formats and make them interoperate, all of us will benefit.