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DVD

A digital optical disc for storing movies and data. Introduced in the U.S. in 1997 and developed by both the computer and movie industries, the disc has the same 120mm/4.75" diameter as a CD but...

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Definition: DVD

A digital optical disc for storing movies and data. Introduced in the U.S. in 1997 and developed by both the computer and movie industries, the disc has the same 120mm/4.75" diameter as a CD but holds 4.7GB rather than 700MB. Whereas CDs use only one side, DVDs can be recorded on both sides as well as in dual layers.

A DVD was first a "digital videodisc" and then a "digital versatile disc." Today, a DVD is simply a "DVD," and, in practice, the term refers to all DVD formats. Modern DVD drives read and write all major CD formats and the following DVD formats, except for DVD-RAM, which requires its own drive. Newer home theater DVD players support these formats for reading. See CSS, DVD region codes and optical disc.

DVD-Video - SD Movies
DVD-Video is the movie format, which uses MPEG-2 compression to provide approximately two hours of video per side at 480i standard definition (SD) TV resolution. When most people say "DVD," they mean DVD-Video; however, many erroneously refer to high-definition Blu-ray discs as DVDs. See DVD-Video, DTV and Blu-ray.

DVD-ROM - Read-Only Data
Designed for data files, a DVD-ROM disc is a higher-capacity CD-ROM, and like CD-ROMs, DVD-ROMs are pressed at the factory. See DVD-ROM.

DVD-R/DVD+R - Burnable
DVD-R and DVD+R are competing write-once formats for burning movies or data. They function like high-capacity CD-R discs. See DVD-R and DVD+R.

DVD-RW/DVD+RW - Rewritable
DVD-RW and DVD+RW are competing formats that can be rewritten 1,000 times. Aimed at the consumer, 1,000 rewrites are considered adequate. See DVD-RW and DVD+RW.

DVD-RAM - Rewritable
A DVD-RAM functions like a removable hard disk with a similar file structure. Although DVD-RAMs can be rewritten 100,000 times before they are no longer usable, they are not a popular medium. See DVD-RAM.

DVD-Audio - High-Quality Music
DVD-Audio was designed to supersede the music CD, but like its SACD counterpart, never caught on. See DVD-Audio.

Plus and Minus: +R, +RW, -R, -RW
The formats endorsed by the DVD Forum have a hyphen in their names and are verbalized as "DVD Minus" or "DVD Dash." The competing formats from the DVD+RW Alliance use a plus sign. Starting in 2002, drives supporting both formats were introduced. See DVD Forum and DVD+RW Alliance.

For drive specifications (2x, 4x, 8x, etc.), see DVD drives. For DVD storage specifications, see DVD storage capacities.


DVD


Sides and Layers
DVDs come in any combination of single or double sided with single or double layers. This shows the laser beam contacting the recorded surface in all of the possibilities.



DVD


DVD Vs. CD-ROM
At minimum, the capacity of a DVD is seven times that of a CD-ROM because its tracks, pits and lands are more than twice as dense. It also uses more efficient recording algorithms. Add a second layer or record on both sides of the DVD, and capacity is doubled. (Image courtesy of C-Cube Microsystems.)



DVD





THIS DEFINITION IS FOR PERSONAL USE ONLY
All other reproduction is strictly prohibited without permission from the publisher.
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