Compatibility counts

Emedia Professional, May, 1998 by Dana J. Parker

At the DVD Professional Conference held February 1-3, 1998 in Orlando, Florida, attendees witnessed an exciting, and for some, unexpected switch: the optimism and enthusiasm of people who are actually using the technology, in place of the optimism and enthusiasm of those who are trying to sell it. In spite of some things and because of others, it almost looks as if there's a chance for DVD to succeed.

Unfortunately, due to all the fuss generated over the past three years or so about competing DVD formats, this group of DVD believers remains small. For most potential developers, DVD is still an unsettled area not conducive to exploration. The wisest course, for those who don't relish reincurring the arrow wounds they received as pioneers of multimedia on CD-ROM, is to let others blaze the trail this time.

Throughout DVD's development, the members of the DVD Forum have proven their own worst enemies in the cause of creating a unified format. In the case of the battle between MMCD and SD, only a third party's ultimatum--give us a single compromise format or none at all--forced the factions to make an uneasy peace with each other. Then it was Hollywood versus the manufacturers, and Hollywood won. Now that all the read-only formats--with DVD-Audio a notable exception--have been settled, for better or for worse, another battle looms for rewritable DVD. The choices are DVD-RAM, backed by the DVD Forum; DVD RW, supported by Philips, Sony, and Hewlett-Packard; and the latest, Pioneer's DVD-R/W. At first glance, the formats are functionally identical. Only by examining and understanding the underlying technology is it possible to judge which one is more suited for a certain application.

BULLY DIPLOMACY: A SIMPLE BUT SUSPECT SOLUTION

Rewritable DVD has been cause for acrimony, angry accusations, and the kind of chest-thumping we haven't seen since the DVD Forum companies agreed to stop dissing each other and 9tart jointly dictating the terms of DVD to the rest of the world. Some parties believe the answer is to force a compromise (a la MMCD versus SD) or to recognize one DVD rewritable format as sufficient for all purposes and applications (a la DVD-Video as designed by Hollywood).

This approach would simplify matters considerably. DVD-ROM drive manufacturers and computer OEMs could confidently start supplying drives capable of reading the chosen rewritable format. The drives would proliferate, providing the installed base of read-only drives that is a requirement for the widespread adoption of a rewritable format. The rewritable format chosen would work well for some applications, and not at all for others. This scenario doesn't seem likely, and even more important, it doesn't seem good.

At the heart of the poor prognosis are the fundamental differences between DVD and CD. It's customary to think of CD as a "family" of formats, each one built upon and related to the others, from Red Book CD Audio to Orange Book Part III for CD-RW. The same is not true of DVD. Instead of a built-in backwards compatibility between read-only and recordable and rewritable formats, achieved over nearly two decades, DVD represents built-in, designed incompatibility between read-only and rewritable, achieved in a space of less than two years.

It didn't have to be this way, but that's the way it has evolved. No amount of hand-wringing over the inadvisability of designing DVD-ROM without considering future rewritable formats will make it go away. And it doesn't seem likely that, left to their own devices (so to speak), the proponents of the competing rewritable DVD formats will reach a compromise or back down, nor should they. A single standard for a publishing medium is essential. A single standard for rewritable media is not, but the quality of being readable in existing read-only hardware is a definite plus.

When, whether due to lack of foresight or planned discontinuity, only one of the proposed rewritable mediums offers backwards compatibility with the read-only version, it hardly makes sense to arbitrarily choose one nonbackward-compatible format instead of another. The only option is to let the market decide.

THE ROAD TO READABLE REWRITABLE: OMNIREAD DVD-ROM

There is a way, however, to break the impasse and revive consumer confidence in DVD, one that doesn't depend on the unlikely and unattractive scenario of a lowest-common denominator rewritable format or the even less appealing prospect a perceived format war. The solution is simple: DVD-ROM drive manufacturers, instead of choosing one rewritable format to enable, should manufacture drives that can read all of them.

According to DVD-RAM proponents, making a DVD-ROM drive that can read DVD-RAM is trivial. They have rescinded the cartridge requirement that posed the biggest impediment to backwards compatibility, and claim that the other necessary changes--a couple of servos and some firmware--are simple and inexpensive. The DVD RW camp has always claimed that their format was designed to eliminate extensive redesign of DVD-ROM drives. Pioneer's DVD-R/W, moreover, was designed with backwards compatibility in mind, and Pioneer claims that no retrofitting will be necessary.