DVD9

DVD9 is a designation for a dual‑layer, single‑sided DVD. It refers to discs that hold about twice the data of a standard single‑layer DVD (DVD‑5). A typical DVD‑9 has a nominal capacity of eight gigabytes (roughly 7.4 GiB) on a single side, with usable space around seven to eight gigabytes after formatting and copy protection overhead. The term applies to both pressed (replicated) DVDs and recordable formats such as DVD‑R DL and DVD+R DL, provided they use the DVD‑Video or DVD‑ROM data formats.

Dual‑layer construction uses two data layers on the same side of the disc, separated by a thin spacer. A dual‑layer laser can focus at different depths to read the second layer, enabling roughly twice the data without increasing disc thickness. To read a DVD‑9, the playable device (drive or player) must support DVD‑DL; some older hardware cannot access the second layer, which results in playback or reading errors.

DVD‑9 is commonly used for feature films and other content that requires more than 4.7 GB. It remains compatible with the DVD‑Video standard, including menus, subtitles, and multiple audio tracks, provided the content complies with the standard. Compatibility depends on the disc, player, and firmware, as some older players may not support dual‑layer playback.

See also: DVD‑5, DVD‑R DL, DVD+R DL, DVD‑Video, Blu‑ray.