Q: What is the difference between CD-R & CD+R and DVD-R and DVD+R? What is better?

A: A CD is a writable optical media with a storage capacity of 700 MB of data and 80 minutes of audio. A DVD is a writable optical media with a storage capacity of 4.7 GB of data (single layer) or 8.55 GB of data (double layer). Double layer discs have a second dye layer that allows them to store nearly twice the amount of data.

There is no such thing as CD+R so I’m wondering if you meant to ask the difference between CD-R and CD-RW? CD-R is an optical storage medium that can only be written to once. Once that part of the compact disc has been written to it cannot be erased and overwritten with new data. A CD-RW is a re-writable compact disc that allows you to erase the original data and record new information in its place. Re-writable CDs (CD-RW) are more versatile than CD-Rs in this respect, but they cost more and have slower access speeds.

DVD-R and DVD+R are competing DVD standards. DVD+R is generally accepted to be the better of the two because of the more precise tracking and error control system it uses when writing at high speeds. This is not to say that DVD-R discs are not reliable, but DVD+R tends to be more so. All new DVD drives are hybrids that support both the DVD-R and DVD+R formats, and are labeled DVD±RW to indicate that they handle both formats.

Blank DVD media labeled DVD-RW and DVD+RW are simply re-writable DVDs (that’s what the “W” on the end means). DVD-R and DVD+R discs are not re-writable.

If you see a DVD specification with DL on the end, that indicates Double Layer capability. DL discs have almost twice the storage capacity of a single layer disc. For example, a DVD drive labeled as DVD±RW DL is a hybrid drive supporting both the DVD plus and DVD dash formats, re-writable discs, and dual-layer DVD discs. All of the DVD movies currently for sale use DL technology. Have you noticed a slight pause halfway through the middle of most movies while they are playing in your home? That’s your DVD player switching from the first layer of the disc to the second.

Q: How can I tell how fast my CD/DVD writer is? (e.g. 8x/4x/16x)

A: This breaks down as write speed / re-write speed / read speed. The write speed is how fast the drive can write to optical media. The re-write speed indicates how quickly (or should I say slowly?) the drive handles re-writable media. The read speed tells you how quickly the drive can read data that has already been written to a disc.

The X stands for times the original transfer rate of a disc. The original data transfer rate for DVD drives when they were released was 1.385MB per second. A DVD drive that writes at 16x is writing data to the optical media at 22.15 MB per second, or sixteen times the original data transfer rate.

The original data transfer rate for CD drives when they were released was 150 KB per second. A 52x CD writer can burn data to a disc at a rate of 7.8 MB per second.

The original data transfer rate for DVD drives when they were released was 1.385MB per second. A DVD drive that writes at 16x is writing data to the optical media at 22.15 MB per second, or sixteen times the original data transfer rate.

Sean McCormick
A+, Network+, Linux+, CTT+, I-Net+
MCSA, MCSE, LPIC1