Dual layer DVD capacity is 8.5GB, which is enough to store two hours of high definition video or around four hours of standard definition video. The dual layer DVD format was first introduced in 2003, and was initially used for DVD-Video discs. However, since the format is also capable of storing data, it has also been used for storage discs, such as those used for backing up computer data.

Dual layer DVD capacity is achieved by using two adjacent layers on a standard DVD disc. The first layer is used for video or data, while the second layer is used …