DVD

In short: Optical disc in the size of a CD but with much more room: 4.7 GB with one layer, 8.5 GB with two. Introduced in the mid-1990s, mainly for films.

In more detail: The DVD (originally Digital Versatile Disc) uses a red laser of about 650 nm. The shorter wavelength allows smaller pits and a tighter track than the CD, so more content fits on the same area.

In Depth

Formats

DVD-Video stores films in MPEG-2 with menus, subtitles and several audio tracks. DVD-ROM is the data variant, comparable to the CD-ROM. Writable are DVD-R, DVD+R (once) and DVD-RW and DVD+RW (repeatedly). Dual-layer discs have two data layers that the laser reads one after the other.

Region codes and copy protection

Many film DVDs are divided into six regions (Europe is region 2). A drive then plays only discs of its region. In addition, CSS encrypts the content. Game DVDs for consoles such as the PlayStation 2 and Xbox are mostly region-free or have their own checks.

Today

The DVD is being displaced by Blu-ray and streaming, but remains common thanks to cheap second-hand prices and a huge selection. Used discs should be clean and free of deep scratches.

See also: CD-ROM, Blu-ray, Optical drives