Can I buy a vowel? The DVD acronym assault

Emedia Professional, Feb, 1998 by Dana J. Parker

if you thought the high-density format saga was confusing back before the proposed read-only specifications were narrowed down to two (MMCD and SD), you're gonna love this: DVD, DVD-V, DVD-ROM, DVD-R, DVD-RAM, DVD RW, DVD-R/W, Divx, DD, DTS, and DSD are just a few of the new acronyms you need to know in order to make a semi-informed evaluation of DVD formats.

Nobody with any pretense of a real life can be expected to keep these straight, and it isn't easy even for those who make it their business to follow the DVD-related formats that seem to be popping up like mushrooms after a spring rain. It doesn't help when companies who might be considered reliable and authoritative sources make conflicting "definitive" statements about what the names of their products are, what they really stand for, and whether a proposed format is real DVD or just an imposter. It's almost as if there were a deliberate intention to maintain a high level of confusion to deflect attention from other issues--after all, if you can't agree on what a format is, how can you possibly hope to discuss its merits or lack thereof?

ABC'S OF DVD: BASIC "DEFINITIONS"

Here's one question that's never been satisfactorily answered: What does DVD stand for? The official word, handed down in June 1996 from Toshiba's Toshio Yajima, secretary of the then-DVD Consortium, at the DVD Forum USA in San Jose, is that DVD stands for DVD--no more, no less, no words. But if you visit Toshiba's Web site, you'll find that DVD means digital video disc. Toshiba also assures DVD developers that DVD stands for digital versatile disc. With these kinds of mixed messages coming from the company that claims to have invented DVD, it's little wonder that the confusion only gets worse.

Even if we could ignore the absence or presence of words behind the acronym, there's still the confusion about what DVD means. Is it a movie on disc? An electronic publishing medium? A technology? Does the prefix DVD denote a technical or cross-platform kinship to other things with the prefix DVD, does it indicate an official standard that the industry can develop to with confidence, or is it simply a meaningless acronym distinguishing something for which the DVD Forum can collect royalties?

DVD-ROM stands for DVD-Read Only Memory, and is defined by Book A of the DVD specification. DVD-Video is defined by Book B of the specification. Basically, DVD-Video is DVD-ROM with something added--a defined application layer--that limits its function to playing movies. Thus, a DVD-Video disc is DVD-ROM, but a DVD-ROM disc is not always DVD-Video. Divx stands for Digital Video Express, and is a variation on DVD-Video; again, a DVD-Video disc or player with something added--this time, Triple DES encoding and a unique serial number--that limits its application. A Divx player plays DVD-Video, but a DVD player won't play a Divx disc.

There's another divisive issue for DVD-Video, though, and this one isn't even nonspecified. The DVD spec calls for either a Dolby AC-3 soundtrack or a PCM (Pulse Code Modulation) soundtrack. Another soundtrack option is DTS (Digital Theater System), which requires a DVD player equipped with a DTS decoder, or an "outboard" DTS decoder as a separate component or incorporated into a hifi receiver. However, none of the existing DVD players on the market is capable of reading a DTS soundtrack on a DVD-Video disc, even if the decoder is already in the system to which the DVD player will be added.

DVD-Audio is not defined yet, but when it is, it will be Book C of the DVD, specification. There are four competing proposals, including DTS. The others we "Super Audio CD" from Philips and Sony, which is based on DSD (Direct Stream Digital) encoding; the Matsushita, Pioneer, JVC, and Toshiba-supported LPCM (Linear Pulse Code Modulation), which is the top end of the current PCM audio specified in the DVD-Video specification, with 24-bit sound and 96-kHz sampling; and an as-yet-unnamed proposal from Sanyo, which will use a sampling frequency of 192 kHz. It is not clear whether discs in any of these formats will play on existing DVD hardware.

NOW DO YOU SPELL RELIEF? DVD R/W

Take a deep breath, now, and read on: DVDR is DVD-Recordable, defined by Book D of the DVD specification, and until the next generation comes along, Pioneer has the field to itself There are no competing proposals to DVD-Recordable, but there is an extension to it, called DVD-R/W--an indication, perhaps, that since all the good letters were already taken, the format's namegivers had to resort to punctuation marks. DVD-R/W stands for DVD-Rewritable, and defines a phase change version of DVD-R media that is rewritable up to 1,000 times. It has the same capacity as DVD-R media, 3.95GB, and as with DVD-R media, the capacity will increase to 4.7GB by year's end. A DVD-R/W drive will record DVD-R and rewrite DVD-R/W, and best of all, DVD-R/W media is readable on first-generation DVD hardware. This backwards compatibility with read-only hardware already in the market is such a brilliant concept upon which to design a format, I can hardly believe it's called DVD.