Dillon

In many cases, sound tracks in more than one language track are present (for example, a dubbed track in the language of the country where the disc is sold in addition to one in the film's original language). DVDs can contain more than one channel of audio to go together with the video content. The vast majority of commercial PAL releases employ AC-3 audio by now. most of Europe) the sound of DVD was supposed to be standardized on PCM and MP2, but apparently against the wishes of Philips, under public pressure on December 5, 1997, the DVD Forum accepted the addition of Dolby AC-3 to the optional formats on discs and mandatory formats in players.

Initially, in countries using the PAL standard (e.g. The vast majority of commercial NTSC releases today employ AC-3 audio. This ensures any standard compatible disc can be played on any standard compatible player. In countries using the NTSC standard any movie should contain a sound track in (at least) either PCM or Dolby AC-3 formats, and any NTSC player must support these two; all the others are optional.

The audio data on a DVD movie can be of the format PCM, DTS, MP2, or Dolby Digital (AC-3). A high number of audio tracks and/or lots of extra material on the disc will often result in a lower bit rate (and image quality) for the main feature. The video resolution on NTSC discs is 720 × 480 and on PAL discs is 720 × 576. Typical data rates for DVD movies range from 3–10 Mbit/s, and the bit rate is usually adaptive.

Commercial DVD movies are encoded using a combination of MPEG-2 compressed video and audio of varying formats (often multi-channel formats as described below). a DVD-player or a DVD computer drive with a software DVD player). DVD-Video discs require a DVD-drive with an MPEG-2 decoder (e.g. While this seems a disadvantage, such drives have a lower seek time as they do not have to change the disc's speed of rotation.

(The track starts at the inner circle of the disc and spirals outward.) The average speed of the drive therefore equals only about 50–70% of the maximum nominal speed. The maximum data rate specified for the drive/disc is achieved only at the end of the disc's track. Most current CD and DVD drives have a constant rotation speed (Constant Angular Velocity, or CAV). As linear (meters per second) track speed grows at outer parts of the disc proportionally to the radius, the rotational speed of the disc was adjusted according to which portion of the disc was being read.

The data on the disc is passed under the read head at a constant rate (Constant Linear Velocity, or CLV). Early CD and DVD drives read data at a constant rate. In physical rotation terms (spins per second), one DVD "speed" equals three CD "speeds," so an 8x DVD drive has the same rotational speed as 24x CD drive. As CD drive speeds are given in multiples of 150 KB/s, one DVD "speed" equals nine CD "speeds," so an 8x DVD drive should have a data transfer rate similar to that of a 72x CD drive.

The data transfer rate of a DVD drive is often given in multiples of 1352 KB/s, which means that a drive with 16x speed designation allows a data transfer rate of 16 × 1352 = 21640 KB/s (21.13 MB/s). The reference data rate of DVD is 11.08 Mbps (million bits per second). Unlike compact discs, where sound (CDDA, Red Book) is stored in a fundamentally different fashion than data (Yellow book et al.), a properly authored DVD will always contain data in files readable by both the UDF filesystem and the ISO 9660 filesystem (often called UDF Bridge format). Almost all DVD writers can write both formats and carry both the +RW and DVD-R/RW logos.

Around 90% of DVD readers (drives and player) can read the recordable formats, with DVD-R having the best overall compatibility in independent tests. As of 2005, both formats are equally popular, with about half of the industry supporting "+", and the other half "-". The "+" (plus) and "-" (dash) are similar technical standards and are partially compatible. However, they are readable by most DVD drives, so they are commonly referred to as DVD+R and DVD+RW.

Instead, they display an "RW" logo, even if it is not rewritable, which some consider to be deceptive advertising. Since DVD+R/RW discs are not technically DVDs as per the DVD Forum standards, they are not allowed to display the DVD logo. The DVD Forum created the official DVD-ROM/R/RW/RAM standards and the DVD+RW Alliance created the DVD+R/RW standards. Each medium can contain any of the above content and can be any layer type.

If there is one barcode, there is only one layer. If there are two barcodes, there are two layers on that side. Another way to identify how many layers a DVD contains is to look at the center ring on the data side(s) of the disc. Double-layered sides are usually gold-colored, while single-layered sides are usually silver-colored, like a CD.

The capacity of a DVD-ROM can be visually determined by noting the number of data sides, and looking at the data side, or sides, of the disc. There are also 8 cm DVDs (not mini-DVD, which usually refers to DVD-Video data on a CD) with a disc capacity of 1.5 GB. The disc may have one or two sides, and one or two layers of data per side; the number of sides and layers determines the disc capacity. The disc medium can be:.

There are a variety of application types for DVD:. As a result, the DVD format is 47 percent more efficient with respect to CD-ROM, which uses a "third" error correction layer. There is no subcode as in CD. CD's error correction, CIRC, is replaced by a powerful Reed-Solomon product code, RS-PC; Eight-to-Fourteen Modulation (EFM) is replaced by a more efficient version, EFMPlus, which uses eight-to-sixteen modulation.

DVD uses a more efficient coding method in the physical layer. This holds for two dimensions, so that the actual physical data density increases by a factor of 3.5. By employing a red laser at 650 nm wavelength (compared to 780 nm for CD) and a numerical aperture of 0.6 (compared to 0.45 for CD), the read-out resolution is increased by a factor 1.65. A single-layer DVD can store 4.7 GB, which is around seven times as much as a standard CD-ROM.

The substrates are half as thick as a CD to make it possible to use a lens with a higher numerical aperture and therefore use smaller pits and narrower tracks. Two such discs are glued together to form a 1.2 mm disc that can be designed to be read from one side (single sided) or both sides (double sided). DVDs are made from a 0.6 mm thick disc of polycarbonate plastic coated with a much thinner reflective layer of aluminium or gold. Toshiba, which maintains the official DVD Forum site [1], adheres to the interpretation of "Digital Versatile Disc." The DVD Forum never reached a consensus on the matter, however, and so today the official name of the format is simply "DVD"; the letters do not officially stand for anything.[2].

"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. However, one GameCube model known as the Panasonic Q (sold only in Japan) allows for DVD playback in the GameCube. Nintendo's GameCube ordinarily cannot play DVDs but uses a modified DVD for its game media. Microsoft's Xbox, released a year after the PlayStation 2, also had the capability to play DVD discs with an add-on remote control kit, cementing the DVD's place in video game consoles.

In keeping with this tradition, Sony has announced that it will implement one of DVD's possible successors, Blu-ray, into its next PlayStation console currently known as the PlayStation 3. As a result, many electronic stores that normally did not carry video game consoles carried PS2s. This proved to be a huge selling point because the PS2 cost about the same as standard DVD players but could do much more. In addition to playing video games developed for the system it was also able to play DVD movies.

In 2000, Sony released its PlayStation 2 console in Japan. While the growth of theatrical films on DVD has cooled recently, that of television programs and music video has increased dramatically. In comparison, the total 2004 US box office for theatrical rentals was $9.53 billion (per the National Association of Theater Owners or NATO). The sales portion of that was $15.5 billion.

According to the Digital Entertainment Group (DEG), all DVD sales and rentals (films, television series, special interests, etc) totaled $21.2 billion in 2004. However, blank VHS tapes are still widely available since DVD video recorders are significantly less common than DVD players. In June 2005, Wal-Mart and several other retailers announced plans to phase out the VHS format entirely, in favor of the more popular DVD format. retailers Circuit City and Best Buy stopped selling VHS tapes in 2002 and 2003, respectively.

Major U.S. 27.3 M rentals VHS). DVD rentals first topped those of VHS during the week of June 15, 2003 (27.7 M rentals DVD vs. Most, but not all, movie "sets" or series have been released in box sets, as have some entire seasons or selected episode volumes of older and newer television programs.

The price of a DVD player has dropped to below the level of a typical VCR (although DVD recorders are still significantly more expensive than VCRs); a low-end player with reasonable quality can be purchased for under $50 US in many retail stores and many modern computers are sold with DVD-ROM drives. As of 2006 the situation is reversed; DVDs make up the bulk and VHS is a slim minority. At that point Wal-Mart began to offer DVD players for sale, but DVDs represented only a small part of their video inventory; VHS tapes of movies made up the remainder. By the spring of 1999 the price of a DVD player had dropped below $300 US.

The first titles released in the U.S., on March 19, 1997, by Lumivision, authored by AIX Entertainment, were IMAX adaptations: Africa: The Serengeti, Antarctica: An Adventure of a Different Nature, Tropical Rainforest, and Animation Greats. The movie had the first test for 2.1 surround sound. The first pressed DVD was the movie Twister in 1996. The first DVD players and discs were available in November 1996 in Japan, March 1997 in the United States, 1998 in Europe and in 1999 in Australia.

The result was the DVD specification Version 1.0, announced in 1995 and finalized in September 1996. The great advantage of EFMPlus is 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 Toshiba's SD code, which resulted in a capacity of 4.7GB instead of SD's original 5GB. The second modification was the adoption of Philips' EFMPlus.

The first one was the adoption of a pit geometry that allows "push-pull" tracking, a proprietary Philips/Sony technology. Philips and Sony abandoned their MMCD format and agreed upon Toshiba's SD format with two modifications that are both related to the servo tracking technology. 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. 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.

. The official DVD specification is maintained by the DVD Forum. DVDs resemble compact discs as their physical dimensions are the same (12 cm or occasionally 8 cm in diameter) but they are encoded in a different format and at a much higher density. DVD (sometimes known as "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.

DVD-18: double sided, double layer on both sides, 17.1 GB (15.9 GiB). DVD-14: double sided, double layer on one side, single layer on other, 13.3 GB (12.3 GiB). DVD-10: double sided, single layer on both sides, 9.4 GB (8.75 GiB). DVD-9: single sided, double layer, 8.5 GB (7.92 GiB).

DVD-5: single sided, single layer, 4.7 gigabytes (GB), or 4.38 gibibytes (GiB). DVD+RW DL: dual layer rewritable. DVD-RW DL: dual layer rewritable. DVD+R DL: dual layer record once.

DVD-R DL: dual layer record once. DVD+RW: rewritable. DVD+R: recordable once. DVD-RAM: random access rewritable.

DVD-RW: rewritable. DVD-R: recordable once. DVD-ROM: read only, manufactured by a press. DVD-Data (containing data).

Xbox DVD (containing games for Xbox). PS2 DVD (containing games for PlayStation 2). DVD+VR (a variation of DVD-Video used for recording on +R and +RW discs). DVD-VR (containing recorded video and sound, usually from TV or camcorder).

SACD (containing high-definition sound). DVD-Audio (containing high-definition sound). DVD-Video (containing movies (video and sound)).