DVD

DVD. A digital optical disc storage format, invented and developed in the 1990s as a successor to the compact disc. It can store any form of digital data, most commonly used for home video, software distribution, and video games. The format's higher storage capacity compared to its predecessor enabled widespread adoption for full-length feature films with enhanced surround sound audio.

History

The development was a result of a format war in the early 1990s, primarily between two competing consortiums: one led by Sony and Philips, who developed the MultiMedia Compact Disc, and another led by Toshiba, Time Warner, and Panasonic, who championed the Super Density disc. To avoid a costly market conflict similar to the VHS versus Betamax war, the groups, under pressure from major Hollywood studios like Twentieth Century Fox and IBM, agreed to a unified standard in 1995 overseen by the newly formed DVD Forum. The first players and discs were launched in Japan in 1996, followed by releases in the United States and Europe in 1997, rapidly supplanting the VCR and LaserDisc for home video.

Technical specifications

A standard single-layer, single-sided disc has a capacity of 4.7 gigabytes, achieved through several technical advancements over the compact disc. This includes a shorter wavelength laser diode (650 nm red laser versus 780 nm), a smaller pit size, and more efficient modulation and error correction schemes like Eight-to-Fourteen Modulation and Reed–Solomon error correction. The physical dimensions are identical to a CD, with a diameter of 120 mm and a thickness of 1.2 mm, but it comprises two 0.6 mm substrates bonded back-to-back. Data transfer rates for video playback, defined as "1x speed," is 1.321 Mbit/s.

Formats and standards

The ecosystem comprises numerous physical and application formats, standardized in books by the DVD Forum. Read-only formats include DVD-ROM for general data and DVD-Video for motion pictures. Recordable variants encompass write-once DVD-R and DVD+R (developed by the DVD+RW Alliance) and rewritable DVD-RW, DVD+RW, and DVD-RAM. For video content, the primary compression standard is MPEG-2, with audio support for formats like Dolby Digital, DTS, and Linear PCM. Regional playback control codes were implemented to allow film distributors to control the international release of theatrical films.

Production and replication

Commercial pre-recorded discs are produced via a high-volume injection molding process known as replication. A glass master is created from the source data using a laser beam recorder. This master is used to create a nickel stamper, which is then mounted in an injection molding press to produce polycarbonate substrate discs. The data layer is coated with a reflective material, typically aluminium, and bonded to a blank substrate. The final disc is printed with artwork using screen printing or offset printing. Recordable discs are manufactured with a pre-grooved spiral and a layer of organic dye that is altered by a consumer's DVD recorder laser.

Uses and applications

The primary application was the distribution of home video entertainment, allowing consumers to own films with superior picture and sound quality compared to VHS. It became the dominant distribution medium for the film industry and television series box sets. Beyond video, the format is widely used for software distribution, including operating system installations from companies like Microsoft, and as the physical medium for video game consoles such as the PlayStation 2, Xbox, and Nintendo GameCube. It also saw significant use for archival data storage and in the distribution of high-fidelity audio in the form of DVD-Audio.

Category:Optical disc authoring Category:Computer storage media Category:Home video Category:1996 introductions