DVDs & Movies

DVD (sometimes called "Digital Versatile Disc", or "Digital Video Disc") is an optical disc storage media format that can be used for data storage, including movies with high video and sound quality. more...

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DVDs resemble compact discs as their physical dimensions are the same (120 mm (4.72 inches) or occasionally 80 mm (3.15 inches) in diameter), but they are encoded in a different format and at a much higher density.

History

In the early 1990s two high-density optical storage standards were being developed: one was the MultiMedia Compact Disc (MMCD), backed by Philips and Sony, and the other was the Super Density disc (SD), supported by Toshiba, Time-Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC. IBM's president, Lou Gerstner, acting as a matchmaker, led an effort to unite the two camps behind a single standard, anticipating a repeat of the costly format war between VHS and Betamax in the 1980s.

Philips and Sony abandoned their MMCD format (not to be confused with MultiMediaCards) and agreed upon Toshiba's SD format (not to be confused with secure digital cards, although the logo for the SD disc format would be re-used for the SD digital card format) with two modifications that are both related to the servo tracking technology. The first one was the adoption of a pit geometry that allows "push-pull" tracking, a proprietary Philips/Sony technology. The second modification was the adoption of Philips' EFMPlus. EFMPlus, created by Kees Immink, who also designed EFM, is 6% less efficient than Toshiba's SD code, which resulted in a capacity of 4.7 GB as opposed to SD's original 5 GB. The great advantage of EFMPlus is its great resilience against disc damage such as scratches and fingerprints. The result was the DVD specification Version 1.5, announced in 1995 and finalized in September 1996. In May 1997, the DVD Consortium was replaced by the DVD Forum, which is open to all companies.

"DVD" was originally an initialism for "Digital Video Disc." Some members of the DVD Forum believe that it should stand for "Digital Versatile Disc" to reflect its widespread use for non-video applications. Toshiba, which maintains the official DVD Forum site, adheres to the latter interpretation, and indeed this appeared within the copyright warnings on some of the earliest examples. However, the DVD Forum never reached a consensus on the matter, and so today the official name of the format is simply "DVD"; the letters do not officially stand for anything.

DVD disc capacity

Note: GB here means gigabyte, equal to 10⁹ (or 1,000,000,000) bytes. Many computers will display gibibyte (GiB), equal to 2³⁰ (or 1,073,741,824) bytes.

Read more at Wikipedia.org