The most obvious hang-up for rewritable DL is that it's incompatible with the installed base of devices. This is due to optical signal levels lower than prerecorded media that will require hardware and firmware to be adjusted to accommodate the differences. Analogous to CD-RW's introduction in 1996, neither existing DVD recorders nor DVD players will be able to write or read rewritable DLs.
History repeatedly teaches that such incompatibilities bring only customer confusion. To introduce more chaos into a market as mature and punch-drunk as DVD is beyond understanding. Inevitably, the industry's answer will be simply to concoct a couple of "RW DL Compatible" logos to slap on future drive nameplates and let the chips fall where they may.
What happens when DVD-RW DL and DVD+RW DL formats inevitably come to market at different times? Are we to endure yet another wave of devices working with one disc type but not both? Where does it end? Is DVD-RAM DL in the cards? We already have an asylum full of DVD-R 3.95GB, authoring and general, +R, -RW, +RW, -RAM 2.6 and 4.7 GB, -R DL and +R DL formats (not to mention recording speed, MID code, -VR, +VR, CPRM, and VCPS complications). Why add to this misery?
I'm told that an important use for rewritable DL will be to bump the recording time of new DVD camcorders. While a single-layer disc (8cm), at 1.46GB, captures 20 to 60 min (1.46GB) of video, a 2.66GB rewritable DL takes in 36 to 110 minutes. But hailing this as a great advance doesn't make sense to me. The basic premise for using a DVD camcorder is to create a compatible disc immediately playable anywhere. To cast aside this universality is to prompt consumers to buy the smaller, cheaper, and even more spacious MiniDV tape.
At least existing recordable DL technology is somewhat compatible with DVD players, so why not leave it at that? And rather than wasting time with incompatible rewritable DL, wouldn't manufacturers be better off promoting hard drives for their camcorders? HDDs are becoming tinier, more voluminous, faster, more power-efficient, and cheaper. Instead of a measly half hour, existing camera-ready hard disks—also known as direct-disk recorders or DDRs--can record a half-day at maximum quality while offering true in-camera editing and high-speed transfer to computers and other outboard devices.
Recording favorite TV shows and data backup are also mentioned as possible uses for rewritable DL but current DVD formats and hard drive combinations easily fill most needs. Beyond intrinsic incompatibility, rewritable DLs will be difficult to manufacture, expensive, and scarce, with little chance for improvement. Most importantly, much higher-capacity Blu-ray Disc (BD-R, BD-RE), HD-DVD (HD DVD-R, HD DVD-RW), or a unified blue laser alternative, are just around the corner and may prove rewritable DL to be as irrelevant as was the quickly (and wisely) forgotten Double Density CD (DDCD).
Hugh Bennett (email@example.com), an EMedia contributing editor, is president of Forget Me Not Information Systems (www.forgetmenot.on.ca), a reseller, systems integrator and industry consultant based in London, Ontario, Canada. Hugh is the author of Understanding Recordable & Rewritable DVD and Understanding CD-R & CD-RW, both published by the Optical Storage Technology Association (OSTA).