A single-sided, dual layer pre-recorded DVD disc format, with a capacity of 8.5 GB (about 4 hours).
A DVD disc that is 8.47 gigabytes (these discs are usally used for commercial DVD's) .
DVD-9 is a single sided dual layer DVD which can fit up to 8.5 GB or 7.95 computer GB which many commercial video DVDs are using today (a DVD-9 is basicly two pressed plastic DVD-5s pressed together, they are not burned). Video DVD supports this format but DVD-R/W and DVD+R/W does not support this format. View DVD9 to DVD5 Converter.