The capacity of a single-layer disc is approximated as 4.7 x 10 bytes.

SL stands for standard single-layer discs, while DL denotes the double-layer variants.

It is a double-sided, single-layer disc; with the 1946 theatrical version on side-A (114 m), and the 1945 film noir version (116 m) on side-B.

Blu-Ray, backed by Sony, Panasonic, and Mitsubishi, among others, can hold up to 25GB on single-layer discs and 50GB on double-layer discs.

The latest DL drives write double layer discs at a slower rate (up to 12x) than current single-layer discs (up to 24x).

Dual-layer recording allows DVD-R and DVD+R discs to store significantly more data, up to 8.5 gigabytes per disc, compared with 4.7 gigabytes for single-layer discs.

It uses 3-inch DVD-R/-RW discs; single-layer discs can hold an hour of footage.

HP's coming double-layer DVD recorder, the Dvd530i ($99), writes single-layer discs at 8x but can manage only 2.4x for double-layer media.

The single-layer disc features an MPEG-2 1080p transfer and PCM 5.1 surround audio.

Dual layer DVDs, which increase the high quality recording mode to almost four hours, are increasingly available, but the cost of this medium was still relatively high compared to standard single-layer discs.