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LaCie DVD±RW Drive User's Manual
FireWire
4.4 DVD Capacity
There are important factors to consider when recording video, audio or data to DVD. The DVD media specification provides
for two physical sizes: 4.7" (12cm) and 3.1" (8cm) (both are .47" (1.2cm) thick). DVD discs can also be single-sided (SS) or
double-sided (DS), and each side can have one (SL) or two (DL) layers of data.
The amount of data or video that a disc can hold are dependent upon factors such as the amount of audio and the degree of
compression of the data, video or audio. For example, a single-layer DVD±R disc typically will store just over two hours of
MPEG-II video, but it is possible to put up to eight hours of VHS-quality video or one hundred sixty hours of audio on a
single-layer disc.
When media companies reference the amount of data that a disc can hold, they represent the total amount in terms of
gigabytes (GB), or a billion bytes (1000 x 1000 x 1000 bytes). This number, though, is not the way in which a computer
addresses the data; to a computer the value is binary and larger than a billion bytes – 1,073,741,824 (1024 x 1024 x
1024 bytes). Therefore, when you put in a 4.7GB DVD disc, the actual available capacity is 4.38GB; and a 8.5GB Double
Layer disc has an actual available capacity of 7.95GB.
Helpful Information
page 24
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