The Specs Explained
Rewritable DVD drive specifications are expressed in a confusing litany of numbers and letters. We'll try to decipher them for you here and let you know which we consider important, somewhat important, or minor in a buying decision.
Important: Disc Formats
DVD burners today can write and rewrite to a variety of disc formats. What all the formats mean and how to distinguish among them are the primary questions facing prospective buyers. Most DVD burners can write to both write-once (R) and rewritable (RW) media. Each type of media comes in two formats: DVD+R and DVD-R; and DVD+RW and DVD-RW. You'll want a DVD burner that supports both + and - formats for maximum compatibility. DVD-RAM is useful for backups, or if you have a living-room DVD recorder that can burn to DVD-RAM--and you actually use the format for your recordings.
All DVD burners can write to both single-layer and dual-layer (or double-layer) formats. Single-layer discs hold 4.7GB of data. Dual- or double-layer discs hold 8.5GB of data.
Write-once DVD--which encompasses both DVD-R and DVD+R--is the most compatible DVD format, especially for sharing discs with living room DVD players. DVD-R SL and DL (single-layer and dual-layer) and DVD+R SL and DL (single-layer and double-layer) are the four write-once variants.
DVD-RW, DVD+RW, and DVD-RAM are three rewritable variants you might encounter. Be sure not to buy one of the older, first-generation DVD+RW burners that lack write-once DVD.
Important: Write-Once DVD Speeds
Most of the latest drives are reasonably comparable in speed; however, it is common to go into retail stores and see older stock--drives that are slower. Check the double-layer and single-layer write speeds before you buy--you'll find a huge difference between 2.4X double-layer DVD-R writes and an 8X or 10X write, for example. The current maximum speed ratings: 20X for DVD-R SL and DVD+R SL; 8X for DVD-R DL; 10X for DVD+R DL.
Important: Rewritable-DVD Speeds
DVD-RW and DVD+RW are about equally compatible with most DVD drives and DVD players. But DVD-RW usually takes longer to format than DVD+RW. DVD-RAM's higher rewrite rating--up to 100,000 rewrites, compared with up to 1000 for DVD-RW and +RW--and robust error correction capabilities make this a good format for data. But DVD-RAM is less compatible with other DVD drives and players.
Currently, the maximum write speeds are 6X for DVD-RW, 10X for DVD+RW, and 12X for DVD-RAM.
Somewhat Important: Interface
Internal drives--as with other storage devices--tend to be cheaper than external ones. Pick a Serial ATA (or SATA) internal drive if you have a newer PC; you won't see a performance boost, but the more efficient SATA cables can help improve air flow in your system.
If you're buying an external drive, pick one with an interface that matches what's installed on your computer--or pick a drive that supports both FireWire and USB 2.0 for maximum flexibility. And choose your drive carefully, based on your needs. If you choose a slimline DVD burner, for example, you'll make a significant sacrifice in speed, but you'll gain portability. A full-size, "half-height" drive--like the one you'd see in your PC, except that it's housed in an external enclosure--will provide the performance you'd expect from a desktop drive.
Somewhat Important: Software
If you know how you plan to use your drive, you may get a better deal if the drive includes the software you'll need. Check to see how complete the OEM bundle of the burning software (such as Roxio's Easy Media Creator or Nero's Nero Express) is; also, see if the burner includes backup software or additional video or image editing software.