About Dual Layer DVDs

Function

Dual layer DVDs were designed to hold more data than their single layer counterparts. Single layer DVDs, when burned, hold data on one layer on the disc. Dual layer DVDs, as their name suggests, can hold information on two different layers - this doubles how much information they can hold.

Dual layer DVDs come in a few different types. First, there are DVD+R dual layer (or DL, for short) and DVD-R DL discs. These types generally are not all that different, with the exception that a DVD-R drive cannot read DVD+R media, and vice versa. Hybrid drives that can handle both types will be labeled with both a "+" and a "-." These can only be burned once, and cannot be rewritten.

Next are DVD+RW and DVD-RW discs. These discs can be burned an estimated 1000 times, which means you can physically erase the data on the discs and burn them again if you so choose.

There are a few different physical sizes of dual layer DVDs, all of which affect the amount of data each disc can hold. A "single sided" dual layer DVD comes in two sizes - 8cm and 12cm. The 12cm size is the standard size of a normal DVD, and can hold 8.5GB of information. The 8cm size is smaller than a standard DVD, and can only hold 2.6GB of information.

Both of these sizes of DVDs also come in "double sided" versions - that is to say that both sides of the DVD can have information written to them, thus doubling the amount of data they can hold over their single sided counterparts. Of this type, a 12cm DVD can hold 17.1GB of information, and an 8cm DVD can hold 5.2GB of information.

The obvious benefit of using dual layer DVDs for your burning is increased size. You can hold twice the amount of data of a single layer DVD. This means that if you're burning a movie, you can have more room on the disc for audio and video quality, which will result in a better looking version of the movie. If you're burning files from your hard drive to the disc, you can hold twice as many. This makes long processes like backing up the contents of your hard drive or transferring data to a new computer not only easier, but much faster.

When attempting to burn a dual layer DVD, you have to take into consideration that only specially labeled drives have the ability to read and write to them. These writer drives will be clearly labeled "dual layer" compatible.

If you burn a movie to a DVD, the information is going to be spread across both layers of the disc. When watching the movie, the player has to switch between the layers, which might trigger a slight pause in the audio and video. This is normal.