Recordable DVD - The (Standards) War of the (DVD) Worlds

by Roger Wyatt
Summer 2001

Imagine recording your favorite movies and TV programs onto DVD, and imagine this being as simple as using an ordinary VCR. This vision is well on its way to becoming a reality. In fact DVD player-recorders have already invaded Japan and have begun to make the journey across the Pacific to the US.
Unfortunately, there is more to recordable DVD than meets the eye. When the DVD manufacturers told us that the initials DVD stood for Digital Versatile Disc, they weren't kidding. The various standards vying for consumer dollars are DVD-R, DVD-RW, DVD+RW and DVD-RAM. The good news is these are very exciting technologies. The bad news is they aren't all compatible with one another (see DVD Format Compatibility sidebar). This article will help you understand the difference between formats and bring you up to speed on some of the issues holding up the DVD VCR.

The Standards War
The standard that started it all was DVD-Video, those discs you pop in your DVD player to watch feature films and interactive productions. Though not used at this time, the standard supports a capacity of up to 9.4GB per side - on a two-sided disc, that's enough space to hold three full-length feature films. But where did that standard come from? Who set it up?
The answer to both questions is the DVD Forum, a standards committee comprised of representatives from approximately 220 companies including Hitachi, JVC, Matsushita, Mitsubishi, Philips, Pioneer, Sony, Thomson, Time Warner, and Toshiba. With almost every major consumer electronics company in the world in the membership, the goal was to hammer out uniform standards that the entire industry would support.
Somehow that unity fractured and DVD manufacturers divided into multiple camps. It's as if, all of a sudden, somebody stood up and yelled, "Format fight!" Pretty soon, everyone was involved. Except the consumer. What's the difference? Let's have a look.

A Look at the Formats
DVD-RAM is a recordable and rewritable standard supported by the DVD Forum. The DVD-RAM medium is a DVD-disc in a permanent cartridge. These cartridges, and the drives that accept them, have been on the market for some time. Long enough, as a matter of fact, to have a couple of generations. The current second-generation disc holds 4.7GB on a side. Also there is a smaller version of the format, the new 80mm disc (some refer to it as an eight-centimeter disc). Those little fellers hold 1.46GB on a side. They are starting to appear as the format of choice for new media recording devices. For example, Hitachi recently incorporated it into a digital camcorder and Sony into some digital still cameras.
The good news about DVD-RAM devices is you can buy them now. The bad news is the cartridges don't play in DVD-Video machines, only in compatible DVD-RAM drives. DVD-RAM units, like Panasonic's DMR E-10, are starting to appear on the market and will play DVD-Video. But DVD-Video players will not play DVD-RAM discs. Are we still together on this?
DVD-R is a write-once version of DVD. It has a single-sided capacity of 4.7GB, and will play on most DVD-Video players and DVD-ROM drives. There may one day be DVD-R devices that emulate living room VCRs, but the first affordable ones will likely be in computers. Apple announced the release of a DVD-R drive in a G4 tower, which is the first significant step by a major computer manufacturer toward providing optical video recording to the masses.
DVD-RW is a rewritable version of the DVD format supported by most members of the DVD Forum. In its data structure, it is very similar to DVD-RAM, except that DVD-RAM records to disk in sectors and tracks, much like a hard drive, DVD-RW records sequentially, more akin to a phonograph. DVD-RW holds the same 4.7GB per side, and can rewritten to up to 1,000 times. This format is the current favorite among manufacturers and may be poised to become the successor to VHS videotape.
DVD+RW is the rewritable standard that Sony, Phillips and Hewlett-Packard cooked up to compete with DVD-RAM. Note the use of the plus sign instead of the dash (or minus sign). While Philips and Sony are members of the DVD Forum, they believe that DVD+RW is more compatible than DVD-RAM with existing DVD-ROM drives and the DVD-Video player in your den. The only fly in the ointment is the lack of support as a standard by the DVD Forum.

What'll They Do?
Let's stop the data barrage and think about why consumers are so excited about recording on DVD. DVD recorders clearly can become replacements for the venerable VCR.
All these formats have a 4.7GB capacity per side. Using MPEG-2 compression format, you can record and store around two hours and twenty minutes of material in 4.7GB. That makes this gaggle of DVD recording formats roughly comparable with a T-120 VHS videotape in terms of capacity. Recordings will be encoded in MPEG-2 with Hybrid VBR (variable bit rate) technology to tweak MPEG-2 compression ratios in real time. This gets you a choice of recording modes including XP mode for one hour, SP mode for two hours and LP mode for four hours of recording.
Image quality is another benefit of DVD. Anyone who has seen DVD-Video can't help but notice how much better it looks than VHS. There are numerous ways that DVD is superior to VHS, starting with the signal type and format. DVD is component digital video while VHS is composite analog. DVD has a resolution of 720x480 as compared with VHS' nominal resolution of 240x480 (all standard NTSC television images are 480 visible scan lines high out of the full raster of 525), making DVD-Video three times more resolute than VHS. (See the DVD vs. VHS sidebar for a detailed comparison).
DVD also offers random access to content. That means no more shuttling through videotapes to find favorite sequences. Simply create chapter indexes that will allow you to see the entire contents of the disc and click an icon to jump from segment to segment or sitcom to sitcom.
Other features include 480-line progressive scanning, Dolby Digital® 5.1 channel surround system as well as two- channel audio playback, random access, instant recording, automatic find-record-space function, on-screen titles, user developed playlists and more.

On the Horizon
Is all this just an exercise in techno-nirvana vaporware? Will there ever be any product that one can actually buy and that will produce a disc playable in standard DVD-video players? The answer to that question is easy. Yes. It's just a matter of (not very much) time.
So what can we take away from this admittedly confusing, fluid, but equally intriguing DVD situation? For now, the best advice may be for each consumer to approach any recordable DVD purchase with a combination of caution and education. Until the format wars subside and a winner reigns supreme, each purchase is a gamble.