DVD

DVD (also known as "Digital Versatile Disc" or, incorrectly, "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 diameter is the same (120 mm or 4.72 inches, or occasionally 80 mm or 3.15 inches), but they are encoded in a different format and at a much higher density.

All read-only DVD discs, regardless of type, are DVD-ROM discs. This includes replicated (factory pressed), recorded (burned), video, audio, and data DVDs. A DVD with properly formatted and structured video content is a DVD-Video disc. DVDs with properly formatted and structured audio are DVD-Audio discs. Everything else (including other types of DVD discs with video) is referred to as a DVD-Data disc. Many people use the term "DVD-ROM" to refer to pressed data discs only, but that is not technically correct.

The term DVD is also being applied as a generic term to describe newer video formats, both Blu-Ray and HD-DVD.

History

In the early 1990s two high-density optical storage standards were being developed; one was the MultiMedia Compact Disc, backed by Philips and Sony, and the other was the Super Density disc, 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 videotape format war between VHS and Betamax in the 1980s.

Philips and Sony abandoned their MultiMedia Compact Disc and fully agreed upon Toshiba's SuperDensity Disc with only one modification, namely EFMPlus. EFMPlus was chosen as it has a great resilience against disc damage such as scratches and fingerprints. EFMPlus, created by Kees Immink, who also designed EFM, is 6% less efficient than the Toshiba code, which resulted in a capacity of 4.7 GB as opposed to the original 5 GB. The result was the DVD specification, finalized for the DVD movie player and DVD-ROM computer applications in December of 1995. In May 1997, the DVD Consortium was replaced by the DVD Forum, which is open to all other companies.

"DVD" was originally used as an initialism for the unofficial term "digital videodisk". It was reported in 1995, at the time of the specification finalization, that the letters officially stood for "digital versatile disc" (due to non-video applications), however, the text of the press release announcing the specification finalization only refers to the technology as "DVD", making no mention of what (if anything) the letters stood for. A newsgroup FAQ written by Jim Taylor (a prominent figure in the industry) claims that four years later, in 1999, the DVD Forum changed the official name of the format to "DVD", and that the letters no longer stand for anything. The official DVD specification documents have never defined DVD. Usage in the present day varies, with "DVD", "Digital Video Disc", and "Digital Versatile Disc" all being common.

Read more at Wikipedia.org