Dual layer
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. 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 specification 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 due to its 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. Sony first introduced the DVD-Video format in Japan in November 1996, in the United States in March 1997 (test marketed), in Europe and Brazil in 1998 and in Australia in 1999. In May 1997, the DVD Consortium was replaced by the DVD Forum, which is open to all other companies.
Etymology
The official DVD specification documents have never defined the initialism DVD. Usage in the present day varies, with Digital Versatile Disc, Digital Video Disc, and DVD being the most common.
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 stated that the format name was simply the three letters "DVD" and did not stand for anything.
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 capacity
DVD recordable and rewritable
Main article: DVD recordableHP initially developed recordable DVD media from the need to store data for backup and transport.
DVD recordables are now also used for consumer audio and video recording. Three formats were developed: DVD-R/RW (hyphen/dash), DVD+R/RW (plus), and DVD-RAM.
Dual-layer recording
Dual-layer recording allows DVD-R and DVD+R discs to store significantly more data, up to 8.54 gigabytes per disc, compared with 4.7 gigabytes for single-layer discs. DVD-R DL was developed for the DVD Forum by Pioneer Corporation; DVD+R DL was developed for the DVD+RW Alliance by Philips and Mitsubishi Kagaku Media (MKM).
A dual-layer disc differs from its usual DVD counterpart by employing a second physical layer within the disc itself. The drive with dual-layer capability accesses the second layer by shining the laser through the first semitransparent layer. In some DVD players, the layer change can exhibit a noticeable pause, up to several seconds. This caused some viewers to worry that their dual-layer discs were damaged or defective, with the end result that studios began listing a standard message explaining the dual-layer pausing effect on all dual-layer disc packaging.
DVD recordable discs supporting this technology are backward compatible with some existing DVD players and DVD-ROM drives. Many current DVD recorders support dual-layer technology, and the price is now comparable to that of single-layer drives, although the blank media remains more expensive. The recording speeds reached by dual-layer media are still well below those of single-layer media.
There are two modes for dual-layer orientation. With parallel track path (PTP), used on DVD-ROM, both layers start at the inside diameter (ID) and end at the outside diameter (OD) with the lead-out. With Opposite Track Path (OTP), used on many DVD-Video discs, the lower layer starts at the ID and the upper layer starts at the OD, where the other layer ends; they share one lead-in and one lead-out. However, some DVD-Video discs also use a parallel track - such as those authored episodically, such as a disc with several separate episodes of a TV series, where more often than not, the layer change is in-between titles and therefore would not need to be authored in the opposite track path fashion.
DVD-Video
Main article: DVD-VideoDVD-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. 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. Currently DVD-Video is the dominant form of home video distribution worldwide.
Although 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, 25, or 23.976 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 such as menus, selectable subtitles, multiple camera angles, and multiple audio tracks.
DVD-Audio
Main article: DVD-AudioDVD-Audio is a format for delivering high-fidelity audio content on a DVD. It offers many channel configuration options (from mono to 7.1 surround sound) at various sampling frequencies (up to 24-bits/192 kHz versus CDDA's 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 sample resolution, 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.
Security
Main article: Content Protection for Recordable MediaDVD-Audio discs employ a DRM 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. 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.
Improvements and succession
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.
However, unlike previous format changes (e.g. audio tape 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 87% of video sales and approximately one billion DVD player sales worldwide. Consumers initially were slow to adopt Blu-ray, partly due to the cost. By 2009, 85% of stores that sold DVD sold Blu-ray Discs. Currently, Blu-ray players are selling for $198 USD, while titles retail for as cheap as $9.86 USD (but are usually significantly higher in price than SD DVD releases, at a more common $20–$30 USD price). A high-definition TV and appropriate connection cables are also required to take advantage of Blu-ray disc. Some analysts suggest that the biggest obstacle to replacing DVD is due to its installed base; a la
Latest News
Japan's royal couple tour Ottawa area
Japanese Emperor Akihito and Empress Michiko toured the Ottawa region Saturday, the first official stop on their visit to Canada.
Tory ad suggests Bloc protecting child traffickers rather than children
Bloc Québécois MPs are outraged over Tory attack ads suggesting the separatist party is soft on pedophiles and child traffickers.