Michael Nadeau
Two opposing industry factions have reached a compromise on the standard for future Digital Videodisc (DVD) devices, which are expected to replace today's CD-ROM drives. The new standard is targeted to ultimately replace the VCR as an in-home video-playback device.
But don't throw out your VCR just yet: The first DVD devices won't appear until late 1996. And it may take years before real-time compression, which will be required to record TV programming, will be available for DVD at consumer-level prices.
The new standard combines elements of two different proposals. A proposal from Philips and Sony, called Multimedia CD-ROM (MMCD), specifies that future DVD devices will be able to play current CD-ROM discs. A consortium led by Matsushita, Time Warner, and Tosh
iba favors a higher-capacity specification, called Super Density (SD), that's incompatible with current CD-ROM discs.
Backward compatibility has been incorporated into the new standard: All DVD devices, including TV set-top boxes and computer drives, will be able to read regular CD-ROMs. Also, discs for the new standard will be the same size as current CD-ROM discs.
The unified specification
allows for 4.7 GB of space on one side of a disc -- which is enough to hold 133 minutes of MPEG-2 video. But that capacity can potentially be quadrupled to about 18 GB, because the new standard incorporates double-sided and double-layer options.
The specification calls for four formats in all. Philips and Toshiba officials say the single-sided, single-layer approach will likely dominate as the preferred medium for the first DVD titles, because 4.7 GB is enough to satisfy most computer applications and to run many movies. The other formats are single-sided, dual-layer (about 9.4 GB); doub
le-sided, with single-layer on one side and dual-layer on the other (about 14.1 GB); and double-sided, with dual-layer on both sides (about 18.8 GB). The double-sided option, proposed by the Toshiba consortium, requires you to manually flip the disc.
Double-sided and double-layer technologies are not new, but neither has ever been produced in mass quantities. But neither group anticipates problems with manufacturing the new media. Rob van Eijk, director of recordable products at Philips Key Modules (San Jose, CA), expects the cost of single-sided, single-layer DVD media to be comparable to that for CD-ROMs. He dismisses as pessimistic estimates that double-sided or double-layer discs could cost about twice the price of CD-ROMs.
Performance will be another DVD benefit. No benchmarks exist as yet for the new unified format, but van Eijk says that Philips/Sony MMCD drives have a 1.4-MBps data transfer rate (roughly equivalent to a 8 or 10 speed), versus about 0.6 MBps for a quad-speed CD-ROM drive.
DVD computer drives will probably arrive in late 1996, shortly after the first DVD TV set-top boxes are released. Officials at Philips wouldn't provide pricing estimates for the first DVD devices, but Toshiba says its eventual target price for a set-top box is $500.
Infotech (Woodstock, VT), a CD-ROM research firm, predicts that more than 2 million high-density CD drives will be sold in 1997, the first full year the technology will be available. The firm also predicts that 60 percent (1.2 million) of those drives will be used in personal computers, primarily for games and reference titles that often require more than one CD-ROM now.
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The unified DVD specification allows the option of bonding two translucent data layers together to allow about 9 GB of data storage per side. The DVD reader merely adjusts the focus of the laser to read a given layer.
DVD May Eventually Threaten VCRs
