DVD

History

In 1993, two high-density optical storage formats were being developed; one was the MultiMedia Compact Disc (MMCD), backed by Philips and Sony, and the other was the Super Density (SD) disc, supported by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC.
Representatives of the SD camp approached IBM, asking for advice on the file system to use for their disk as well as looking for support for their format for storing computer data. A researcher from IBM's Almaden Research Center received that request, and also learned of the MMCD development project. Wary of being caught in a repeat of the costly videotape format war between VHS and Betamax of the 1980s, he convened a group of computer industry experts (including representatives from Apple, Microsoft, Sun, Dell, and many others); this group was referred to as the Technical Working Group, or TWG. The TWG voted to boycott both formats unless the two camps agreed on a single, converged standard.[4] Lou Gerstner, President of IBM, was recruited to apply pressure on the executives of the warring factions. Eventually, the computer companies won the day, and a single format, now called DVD, was agreed upon. The TWG also collaborated with the Optical Storage Technology Association (OSTA) on the use of their implementation of the ISO-13346 file system, known as Universal Disk Format (UDF), for use on the new DVDs.
Philips and Sony abandoned their MultiMedia Compact Disc and agreed upon a spec mostly similar to Toshiba and Matsushita's Super Density Disc except for the dual-layer option (MMCD was single-sided and optionally dual-layer whereas SD was single-layer but optionally double-sided) and EFMPlus modulation. 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 modulation technique originally used by Toshiba, 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 1995. The DVD-Video format was introduced first, in 1996, in Japan, to the United States in March 1997 (Test Marketed), mid-late 1998 in Europe and early 1999 in Australia. In May 1997, the DVD Consortium was replaced by the DVD Forum, which is open to all other companies.

Etymology
"DVD" was originally used as an initialism for the unofficial term "digital visual disc".[6] 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).[7] 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.[5] A newsgroup FAQ written by Jim Taylor (a prominent figure in the industry) claims that four years later, in 1999, the DVD Forum stated that the format name was simply the three letters "DVD" and did not stand for anything.[8]
The official DVD specification documents have never defined DVD. Usage in the present day varies, with "DVD", "Digital Video Disc", and "Digital Versatile Disc" being the most common.
The DVD Forum website has a section called "DVD Primer" in which the answer to the question, "What does DVD mean?" reads, "The keyword is 'versatile.' Digital Versatile Discs provide superb video, audio and data storage and access -- all on one disc

DVD-Video
DVD-Video is a standard for storing video content on DVD media. In the U.S., mass retailer sales of DVD-Video titles and players began in late 1997.[17] By June 2003, weekly DVD-Video rentals began out-numbering weekly VHS cassette rentals, reflecting the rapid adoption rate of the technology in the U.S. marketplace.[18][19] Currently DVD-Video is the dominant form of home video distribution worldwide.
Though many resolutions and formats are supported, most consumer DVD-Video discs use either 4:3 or anamorphic 16:9 aspect ratio MPEG-2 video, stored at a resolution of 720×480 (NTSC) or 720×576 (PAL) at 29.97 or 25 FPS. Audio is commonly stored using the Dolby Digital (AC-3) or Digital Theater System (DTS) formats, ranging from 16-bits/48 kHz to 24-bits/96 kHz format with monaural to 7.1 channel "Surround Sound" presentation, and/or MPEG-1 Layer 2. Although the specifications for video and audio requirements vary by global region and television system, many DVD players support all possible formats. DVD-Video also supports features like menus, selectable subtitles, multiple camera angles, and multiple audio tracks.

DVD-Audio
DVD-Audio is a format for delivering high-fidelity audio content on a DVD. It offers many channel configuration options (from mono to 5.1 surround sound) at various sampling frequencies (up to 24-bits/192 kHz versus CDDAs 16-bits/44.1 kHz). Compared with the CD format, the much higher capacity DVD format enables the inclusion of considerably more music (with respect to total running time and quantity of songs) and/or far higher audio quality (reflected by higher sampling rates and greater bit-depth, and/or additional channels for spatial sound reproduction).
Despite DVD-Audio's superior technical specifications, there is debate as to whether the resulting audio enhancements are distinguishable in typical listening environments. DVD-Audio currently forms a niche market, probably due to the very sort of format war with rival standard SACD that DVD-Video avoided.
[edit]Security
Main article: Content Protection for Recordable Media
DVD-Audio discs employ a copy prevention mechanism, called Content Protection for Prerecorded Media (CPPM) developed by the 4C group (IBM, Intel, Matsushita, and Toshiba).
To date, CPPM has not been "broken" in the sense that DVD-Video's CSS has been broken, but ways to circumvent it have been developed.[20] By modifying commercial DVD(-Audio) playback software to write the decrypted and decoded audio streams to the hard disk, users can, essentially, extract content from DVD-Audio discs much in the same way they can from DVD-Video discs.
[edit]Competitor

In 2006, a new format called Blu-ray Disc (BD), designed by Sony, Philips, and Panasonic, was released as the successor to DVD. Another format, HD DVD, competed unsuccessfully with this format in the format war of 2006 to 2008. A dual layer Blu-ray Disc can store 50 GB, almost six times the capacity of a double-dual layer DVD.
However, unlike previous format changes (e.g. vinyl records to compact disc, VHS videotape to DVD), there is no immediate indication that production of the standard DVD will gradually wind down, as they still dominate with around 97% of video sales and with approx: one billion DVD player sales world wide.[21][22] Consumers initially were slow to adopt Blu-ray, partly due to the cost. Currently Blu-ray players are selling for $298 USD[23] or more, while titles retail for as little as $9 USD or higher (but are usually higher in price than SD DVD releases)[24]. One also requires a high-definition TV and appropriate connection cables to take advantage of Blu-ray disc. Some analysts suggest that the biggest obstacle to replacing DVD is due to its installed base; a large majority of consumers are satisfied with DVDs.[25] The DVD had succeeded because it offered a compelling alternative to VHS. In addition, Blu-ray players are designed to be backwards compatible, allowing older DVDs to be played since the media are physically identical; this differed from the change from vinyl to CD and from tape to DVD which involved a complete change in physical medium.
This situation can be best compared to the changeover from 78 rpm shellac recordings to 45 rpm and 33 1/3 rpm vinyl recordings; since the medium used for the earlier format was virtually the same as the latter version (a disk on a turntable, played using a needle), phonographs continued to be built to play obsolete 78s for decades after the format was discontinued. Manufacturers have announced standard DVD releases well into 2009, and the format remains the preferred one for the release of older television programs and films, with some programs such as Star Trek: The Original Series requiring reediting and replacement of certain elements such as special effects in order to be better received in high-definition viewing.[26]
[edit]DVD consumer rights

See full article: DVD Consumer Rights
DVDs that have commercial movies and television content recorded on them are subject to copyright. The rise of filesharing and 'piracy', has prompted many copyright owner to display notices on DVD packaging or displayed on screen when the content is played that warn consumers of the illegality of certain uses of the DVD.
Such notices do not always offer a reliable summary of DVD owners' DVD Consumer Rights.
Generally, retail buyers of commercial prerecorded DVDs are free to sell or exchange their property. Arrangements for renting and lending differ more by geography. In the US, the right to rent or lend out bought DVDs is protected by the first-sale doctrine under the United States Copyright Act. In Europe, rental and lending rights are more limited, thanks to a 1992 European Directive which gives copyright holders broader powers to restrict the commercial renting and public lending of DVD copies of their work.
[edit]See also

DVD authoring
DVD formats
DVD region code
DVD TV games
DVD-Video
MiniDVD
HDTV quality DVD Player
DVD-RAM
DVD Consumer Rights