Too many flavors
How many DVD formats do we need? We explore DVD-R, -RW, +RW, RAM, ROM, Audio, and more.
Paul G Schreier, Contributing Editor

The 17-billion-byte figure mentioned above is for the ultimate DVD—a double-layer, double-sided disc. Somewhat less awesome, the 4.7-billion-byte, single-sided, single-layer disc has established itself as a baseline standard. (See the sidebar "When a gigabyte isn't a gigabyte" for an additional note on DVD capacities.)

DVD represents one of the finest examples of a convergence technology. This single technology is starting to replace products in the consumer space (audio CDs, video laserdiscs, VHS video tapes, and even the game cartridge) as well as in the PC data-storage space (rewritable CD, tape backup, and removable media such as Zip drives). Further showing convergence possibilities, Pioneer has introduced in Japan a car-navigation system that reads 3D city maps from DVD discs. And just last month, Hitachi showed off a DVD-based camcorder; after filming an hour or so of video, you pop the disc into a player in your living room or into the drive in a PC.

Want blood?

Getting to this point has meant traversing a rocky road, but the disputes and controversies are far from over. You thought VHS vs Beta was bloody? You ain't seen nothing yet. For one thing, there's too much at stake. The Consumer Electronics Association notes that DVD players have become the fastest selling product in the history of the industry. Consumers bought more than 4 million players in 1999, up 371 percent from the previous year. The CEA projects sales of 6.5 million units worth $1.5 billion this year.

But the companies whose methods didn't receive validation continue to market their own approaches nonetheless. The situation has gotten to the point where Dana Parker, a consultant, writer, and conference organizer who focuses on optical storage, recently counted 15 different DVD-based formats.

For a product-development team wrestling with which technology to incorporate into next year's gadget, trying to make sense out of this alphabet soup of options is nontrivial. Just for starters, you'll often hear about DVD-ROM, DVD-Audio, DVD-Video, DVD-R, DVD-RAM, DVD-RW, and DVD+RW.

One way to cut through the confusion and understand if and where the technologies play a role is to look at them in the framework of a few basic categories. You can examine the formats as either consumer or PC-oriented. And you can examine them as read-only or recordable. For today, fortunately, both of these breakdowns lead to similar groupings.

Let's start in the living room. Mention the term DVD today, and almost everyone thinks of what is more appropriately called a DVD-Video player. Players that support DVD-Audio formats are available in Japan, and they could be making their debut in US stores by the time this article appears (if domestic manufacturers become convinced that copy-protection issues have been adequately addressed).

It's important to note that DVD-Audio and DVD-Video involve distinct ways of storing bits. It's possible to make an audio disc that won't play in a video player. Until universal players become commonplace, though, manufacturers can make audio discs work on video players by including a Dolby Digital version of the audio within the video area of the disc. Got that?

Sony and Philips have developed a competing scheme, the Super Audio CD, which uses DVD discs. Sony released an SACD player in Japan more than a year ago at $5000. But only a few SACD audio titles have appeared, and the format has generated little market enthusiasm.

The new VCR

While the vast majority of DVD drives are going into video players, the goal of drive manufacturers is to sell competitively priced units that allow consumer recording. In other words, DVD-based VCRs. Once they establish a beachhead in that market, most expect to move their technology over to PCs for data-storage applications.

As you'll see, though, multiple formats are breeding a large degree of confusion among OEMs, reporters, analysts, and users. Because of this format war, comments Michelle Abraham, senior analyst at Cahners In-Stat Group, the DVD recorder market won't enjoy the same kind of exponential ramp up as DVD-Video players. In fact, her group doesn't expect recorder shipments to reach more than 1 million units until 2003. As for which format has the edge in DVD recorders, Abraham admits, "I can't even attempt to predict who will win."

It's possible no one will. For, while uncertainty over recordable DVD continues to brew, PVRs (personal video recorders), which use magnetic hard disks to record video, continue to make inroads into the consumer entertainment pantheon.

Still, various firms and factions are pushing hard to get recordable DVD products into consumers' hands and thereby gain an edge. You can't buy a DVD recorder in the US market yet, but you might expect something soon. Late last year, Pioneer introduced to the Japanese market the DVR-1000, the first consumer DVD video recording unit, which also plays DVD-Video discs. It lists at roughly $2350, and just in the first quarter of this year Pioneer reportedly sold 25,000 units.

The system works with 4.7-billion-byte DVD-RW discs and stores between two and six hours of video, depending on quality. DVD-RW adopts the VR (Video Recording) format specified by the DVD Forum, so you can't play back discs it burns on a standard DVD-Video player, although the firm states that the format "can be made fully compatible for playback with DVD-Video in the future."

With this push from Pioneer, DVD-RW appears to be the most advanced format in terms of availability. Because the media supports roughly 1000 rewrites, this scheme is best suited for consumer use, notes Mark Anderson, a product manager at Plasmon, a firm that specializes in large data-storage systems. He believes that the number of rewrites isn't a crucial spec for living-room products, because the recording function accounts for perhaps 1 percent of the total use of a player. This phase-change erasable format is backward compatible, and discs holding unencoded data play in most existing DVD-Video players and DVD drives.

Limited appeal

It's possible that DVD-RW could present some tough competition for the scheme upon which it's based, DVD-R. The key difference is that DVD-R is a write-once technology using sequential operation. As such, it holds little attraction for consumers and instead appeals mostly to niche markets, such as the archiving of medical records. DVD-R gives software developers a simple and relatively cheap way to develop test discs for their DVD-ROM titles. Software houses and multimedia authors use it to create master discs prior to mass production.

Compatibility with DVD-RAM could become a key feature given that Panasonic is getting ready to ship a DVD-RAM video recorder in Japan at a price point matching that of the Pioneer unit. Further, DVD-RAM supports 100,000 rewrite cycles and thus has much greater appeal for data-storage professionals. For these people, DVD-R's 1000-use limit is a joke. "DVD-RW discs wouldn't survive a week in one of our data-storage jukeboxes," comments Plasmon's Anderson. Panasonic thus expects to start volume shipments of an OEM DVD-RAM drive for PCs this summer with list price near $550. The firm also promises volume shipment of media at $24.95 for a 4.7-billion byte, single-sided disc, or $35.95 for a 9.4-billion byte, double-sided cartridge.

Putting DVD-RAM's availability and capacity to good use, Cygnet Storage Solutions earlier this summer demonstrated the InfiniDISK, a DVD/CD jukebox product line, which controls multiple drives to read and write CDs and DVDs in the same enclosure. The Enterprise version houses as many as 1750 discs and 28 drives.

Beyond the number of write cycles, DVD-RAM also offers defect management and the ability to write and erase individual sectors. In addition, the format uses the same modulation and error-correction schemes as DVD-Video and DVD-ROM, so newer DVD-ROM drives and video players can read the media. In addition, DVD-RAM drives can read all CD formats, as well as DVD-ROM, DVD-Video, and DVD-R discs.

While manufacturers can point out differences in how DVD-RAM and DVD-RW store data physically and in other technical aspects, what consumers notice first is the cartridge associated with DVD-RAM discs. Double-sided media, because it has no safe side on which you can set it down, resides in the cartridge permanently. However, responding to growing consumer requests, manufacturers have now made available single-sided DVD-RAM media as bare rewritable discs and in removable cartridges. The value of the data and how much protection it deserves determines whether or not you use the cartridge. The ability to work outside the cartridge also gives DVD-RAM physical compatibility with other formats.

FORGET TAPES: Hitachi’s DVD-based video camera, using a miniature disc for recording, should go on sale in Japan this month and in the US later this year.

Go ahead anyway

All the previous formats have received approval from the DVD Forum. Given the number of approved formats, it might seem odd that a group of vendors—led by Philips, Sony, and Hewlett-Packard—is pushing yet another scheme. Those firms submitted their creation, DVD+RW, to the Forum for adoption as a rewritable standard. When it wasn't accepted, the group felt so strongly about DVD+RW's advantages that it went ahead on its own. Key among those advantages are that all physical parameters fit within the DVD-ROM spec; reflectivity is in the same range as the dual-layer spec of a read-only disc; and the density is the same as in the single-layer spec. Thus, claim the supporters, it's the only rewritable format that provides full compatibility with the large and growing base of legacy video players and DVD-ROM drives, and it thereby also offers maximum media interchange between consumer equipment and PC platforms.

Detractors feel that the companies pushing the scheme are less concerned about protecting consumer interests than they are about protecting and enhancing the value of their patents, upon which this technology is based.

The latest incarnation of DVD+RW calls for single-sided media with room for 4.7 billion bytes and double-sided media spacious enough for 9.4 billion bytes. Discs aren't yet available, but prices are expected to start around $30 (roughly the same as for other formats). The recorders handle defect management, provide quick formatting of blank discs, and support both sequential and random recording, which eliminates linking sectors. This, plus the option of no defect management, allows DVD+RW discs to be written in a way that should be compatible with many existing DVD readers. Keeping pace with the marketing efforts of Forum-approved schemes, Philips intends to release a DVD+RW video recorder later this year at a price "competitive" to what Pioneer charges, and a PC drive should follow not long after.

Focus on PC apps

While vendors of recordable DVD formats are focusing first on the consumer market, DVD-ROM drives are finding their way into many PCs. Indeed, virtually every major PC manufacturer offers models with DVD-ROM drives, and by the end of last year, approximately 30 million DVD PCs had been shipped. The drives add anywhere from $20 to $200 to the PC's price tag, compared with a CD-ROM-equipped model. Upgrade kits for older machines start at $100.

From this report you might think that there's not much room left in the marketplace for CD drives. Not necessarily. In fact, Cahners In-Stat predicts that in the PC arena CD-ROM drives will continue to outship DVD-ROM drives until 2002. Analyst Abraham adds that PC manufacturers would rather not make that choice and instead are eager for combination CD-RW/DVD-ROM drives. One such option is Ricoh's MediaMaster, a half-height drive that reads CD-ROM and DVD-ROM as well as writes to CD-R and rewrites to CD-RW media. With bundled support software it sells for $400. Toshiba recently announced a similar combination drive.

At the bottom end—entry-level PCs and those given away almost for free—CD-ROMs are still the cheapest option. Consider that you can find CD drives selling for not much more than $10 in OEM quantities, and you can buy an off-brand portable audio player for $25 in any store. At roughly a dollar a disc, CD media is now cheap enough to burn a disc without worrying about having to throw it away later. As for the capacity issue, Sony and Philips are reportedly working on a "double-density CD-R," which will come in write-once and rewritable versions and read existing CD media. So, just as people have been predicting the demise of the video tape and the floppy disk for years, the CD could be around for a long time to come.

Author information

Contributing Editor Paul G Schreier (aa1mi@ARRL.net) is a writer and marketing consultant in Rye, NH. He specializes in DSP, data acquisition, and emerging technologies.