If you've ever shopped for optical media, chances are you've felt a bit confounded by the sheer volume of options on the shelf (or Web site). Buying discs isn't as simple as grabbing the first spindle or box you find--if you don't look carefully, you could end up with media that's the wrong format, the wrong speed, or overkill for what you're planning to do. Even folks who are savvy about optical media can be stymied by cacophony of choices. You know the industry has a problem when you hear experienced pros admit they, too, have inadvertently bought a disc that doesn't work in their PC's optical drive, or the DVD recorder in their living room. With a growing array of media types on store shelves, I figured it's time for a back-to-basics primer to help you navigate the increasingly muddied waters of optical media. There's so much to cover that I'm going to spread it out over a couple of columns. This month, I'll address formats, layers, and disc speeds.
A Dose of +, -, R, RW, and -RAM
To quote from The Sound of Music, let's start at the very beginning. Back in the early days of DVD, the struggle amongst the formats was more significant than it is today--at least for optical drives in computers. Gone are the single-format DVD drives of yore. Today's multiformat drives can handle just about anything you throw at them. Now you've got lots of options: DVD+R, DVD-R, DVD+RW, DVD-RW ... pick your format, and your drive can probably write to it. DVD-RAM remains the sole holdout: Only so-called Super-Multi drives (such as some models from LG Electronics and Panasonic, for example) are capable of writing to -RAM media.
Set-top DVD recorders, unfortunately, have not caught up to DVD burners made for computers. If you've got a DVD recorder, you're still limited in the formats you can use. Typically you get just one set of formats for recordable and rewritable media. For example, one recorder might be compatible with DVD-R and -RW, while another may work with -R, -RW, and -RAM. And a third might support DVD+R and DVD+RW, but not the other three. There are a few recorders that are offer cross-format support: Panasonic's next generation of DVD recorders will add DVD+R to the currently supported DVD-R and DVD-RAM formats; Lite-On and Sony offer some models that can handle both DVD-R/RW and +R/RW.
So which discs should you use? Experiment, and use what works with your DVD recorder and optical drive.
In general, for recordable DVD media, use -R and +R for data or photo archiving, or for recording video you plan to share. Unfortunately, 100-percent compatibility with all DVD players isn't guaranteed: The latest percentage I've heard is about 90 percent compatibility, and the odds get less favorable if you're trying to use your discs in, say, an "ancient" six-year-old DVD player. Beyond that, you can expect little difference between the two formats--they're pretty much on a par in every other way that's tangible to the user, including longevity.
Ditto for the rewritable formats--you won't find many tangible differences between DVD-RW and DVD+RW. DVD-RAM, because of the disc's structure, acts a bit differently than the other rewritable formats, and is even less compatible with other DVD recorders; ultimately, however, it is a rewritable DVD format. Sure, DVD-RAM is rated at a high 100,000 rewrites, as compared with -RW and +RW's 1000 rewrites. But that number assumes the -RAM disc is kept in a cartridge--and that is hardly a safe assumption, given the advent of bare, as opposed to cartridge, DVD-RAM media. (LG's Super-Multi drive is among the handful of Super-Multi drives that support only bare -RAM discs.)
Most users will be best served by DVD-RW and +RW, be it for data backups, regular TV recordings, or testing out DVD movie projects. For example, you can burn a test disc, see how the navigation works, then finalize your project on the more compatible DVD-R or +R. DVD-RAM is useful if you want to time-shift a recording on disc (for example, to pause a live recording, or to record to one part of the disc while watching another part); however, this useful capability of DVD-RAM is moot if you have a DVD recorder with a hard drive, too, as you'll likely record directly to the hard drive.
Tip: Before you buy DVD media, make sure you know which formats your computer's optical drive or your set-top recorder supports.
Single, Dual, and Double Layers
Technically, layers came into the equation a year ago, when double-layer DVD burners first shipped, capable of burning to 8.5GB double-layer media (as opposed to standard 4.7GB single-layer media). But it's only now that layers are starting to have an impact on the market. Double-layer and dual-layer media are slowly becoming more widely available, although disc prices remain high (a three-pack for $35, anyone?).
More importantly, double-layer support is de rigueur in drives at this point, and drives with dual-layer support are imminent. The difference between double and dual layers? Not a whole lot, beyond the nomenclature. The DVD+RW Alliance, which hatches the specs for the DVD+R/RW formats, favors double-layer; dual-layer is the name that the DVD Forum has chosen for the DVD-R/RW formats.
At the moment, both double-layer and dual-layer discs are limited to write-once +R and -R media. However, I'm hearing rumblings that we can expect a double-layer rewritable disc by the end of the year, if not sooner.
Tip: If you don't already have an optical drive that supports the technology, dual- or double-layer media is useless to you. Older drives won't recognize and write to the discs. If you're in the market for a DL drive, check out our May "Top 10 DVD Drives."
The X-Rating Game
2X, 2.4X, 4X, 5X, 6X, 8X, 16X: That's enough options to make your head spin, eh?
Typically, faster drives routinely come out before the media rated for the maximum speed appears on store shelves. The most recent example: Double-layer media was MIA long after drives came to market.
The general rule of thumb is to match the speed rating of the media with the maximum speed that your DVD burner supports either out of the box, or via a firmware update. Doing so will maximize your chance of getting optimal performance from your drive. For DVD-R and DVD+R, the current maximum is 16X; DVD-RW is at 6X; DVD+RW is at 8X; and DVD-RAM is 5X.
You may have to settle for older media that doesn't have the fastest rating available for its type, as newer and faster media often take time to arrive on store shelves. Still, that doesn't mean you won't see a speed boost when you use older media with a new, faster drive. For example, many 12X and 16X DVD+R drives can write at those speeds using 8X media. Likewise, the fastest double-layer DVD+R drives support speeds up to 6X, but most media is still frozen at 2.4X. But no matter: As our first tests of double-layer burners showed, a significant speed boost is possible, even with the slower media. In April's chart, for example, Hewlett-Packard's DVD Writer 640i required 44 minutes, 59 seconds to write to double-layer DVD+R at a mere 2.4X; our Best Buy that month, Toshiba's SD-R5372, took 22 minutes, 24 seconds to perform the same task, at 5X.
Conversely, if you have an older drive, say an 8X burner, you may have no choice other than to buy faster 16X media. This media should work on your drive, but you may need to update the drive's firmware.
One other caveat: Be especially careful to check the media speed if you plan to use the discs with a DVD recorder. Set-top recorders can be more finicky than optical burners in computers, and sometimes they won't recognize newer media speeds, let alone newer types such as double-layer and dual-layer discs. For example, if you have a DVD-RW set-top recorder that records at 2X, it may not recognize the newer 4X or 6X discs. And double-layer and dual-layer media may play back on set-top recorders (may being the operative term, as cross-compatibility is not one of the technology's strong suits), but you won't be able to record to them. Later this year, I expect we'll see the first double-layer or dual-layer set-top recorders; Pioneer has already announced a model for release in Japan.