   #copyright

DVD

2007 Schools Wikipedia Selection. Related subjects: Computing hardware and
infrastructure

   CAPTION: DVD

   Media type: optical disc
    Capacity:  up to 8.5 GB per side
     Usage:    Data storage
                Optical disc authoring
     * Optical disc
     * Optical disc image
     * Recorder hardware
     * Authoring software
     * Recording technologies
          + Recording modes
          + Packet writing

                 Optical media types
     * Laserdisc
     * Compact Disc/ CD-ROM: CD-R, CD-RW
     * DVD: DVD-R, DVD-R DL, DVD+R, DVD+R DL,
       DVD-RW, DVD+RW, DVD+RW DL, DVD-RAM
     * Blu-ray Disc: BD-R, BD-RE
     * HD DVD: HD DVD-R

                      Standards
     * Rainbow Books
     * File systems
          + ISO 9660
               o Joliet
               o Rock Ridge
                    # Amiga extensions to Rock Ridge
               o El Torito
               o Apple ISO9660 Extensions
          + Universal Disk Format
               o Mount Rainier

   DVD (sometimes called "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. DVDs
   resemble compact discs as their physical dimensions are the same (120
   mm (4.72 inches) or occasionally 80 mm (3.15 inches) in diameter) but
   they are encoded in a different format and at a much higher density.

History

   A 12 cm Sony DVD+RW shown in comparison in size to a 7.5 inch Dixon
   Ticonderoga pencil.
   Enlarge
   A 12 cm Sony DVD+RW shown in comparison in size to a 7.5 inch Dixon
   Ticonderoga pencil.

   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. 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.

   Philips and Sony abandoned their MMCD format (not to be confused with
   MultiMediaCards) and agreed upon Toshiba's SD format (not to be
   confused with secure digital cards, although the logo for the SD disc
   format would be re-used for the SD digital card format) with two
   modifications that are both related to the servo tracking technology.
   The first one was the adoption of a pit geometry that allows
   "push-pull" tracking, a proprietary Philips/Sony technology. The second
   modification was the adoption of Philips' EFMPlus. EFMPlus, created by
   Kees Immink, who also designed EFM, is 6% less efficient than Toshiba's
   SD code, which resulted in a capacity of 4.7 GB as opposed to SD's
   original 5 GB. The great advantage of EFMPlus is its great resilience
   against disc damage such as scratches and fingerprints. The result was
   the DVD specification Version 1.5, announced in 1995 and finalized in
   September 1996. In May 1997, the DVD Consortium was replaced by the DVD
   Forum, which is open to all companies.

   "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. Toshiba, which maintains the official DVD Forum site ,
   adheres to the latter interpretation, and indeed this appeared within
   the copyright warnings on some of the earliest examples. However, the
   DVD Forum never reached a consensus on the matter, and so today the
   official name of the format is simply "DVD"; the letters do not
   officially stand for anything.

DVD disc capacity

                         Single layer capacity  Dual/Double layer capacity
      Physical size     GB          GiB         GB            GiB
   12  cm, single sided 4.7 4.38                8.5 7.92
   12 cm, double sided  9.4 8.75                17  15.8
   8 cm, single sided   1.4 1.30                2.6 2.42
   8 cm, double sided   2.8 2.61                5.2 4.84

   Note: GB here means gigabyte, equal to 10^9 (or 1,000,000,000) bytes.
   Many computers will display gibibyte (GiB), equal to 2^30 (or
   1,073,741,824) bytes.

   Example: A disc with 8.5 GB capacity is equivalent to: (8.5 x
   1,000,000,000) / 1,073,741,824 ≈ 7.92 GiB.

Capacity Nomenclature

   The four basic types of DVD are referred to by their capacity in
   gigabytes, rounded up to the nearest integer. The exception to the rule
   is DVD-18, whose capacity is in fact 17 gigabytes.
            DVD type           Name
   Single sided, single layer DVD-5
   Single sided, dual layer   DVD-9
   Double sided, single layer DVD-10
   Double sided, dual layer   DVD-18

DVD recordable and rewriteable

   DVD-R read/write side
   Enlarge
   DVD-R read/write side

   HP initially developed recordable DVD media from the need to store data
   for back-up and transport.

   DVD recordables are now also used for consumer audio and video
   recording. Three formats were developed: -R/RW (dash), +R/RW (plus),
   -RAM (random access memory).

Dual layer recording

   Dual Layer recording allows DVD-R and DVD+R discs to store
   significantly more data, up to 8.5 Gigabytes per disc, compared with
   4.7 Gigabytes for single-layer discs. DVD-R DL (dual layer — see
   figure) was developed for the DVD Forum by Pioneer Corporation, DVD+R
   DL (double layer — see figure) was developed for the DVD+RW Alliance by
   Sony.

   A Dual Layer disc differs from its usual DVD counterpart by employing a
   second physical layer within the disc itself; how the drive with Dual
   Layer capability accesses the second layer is that it could shine the
   laser through the first semi-transparent layer -- This is something
   that normal DVD recordable discs do not have. The layer change
   mechanism in some DVD players can show a noticeable pause, as long as
   two seconds by some accounts. More than a few viewers have worried that
   their dual layer discs were damaged or defective.

   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 point is
   comparable to that of single-layer drives, though the blank media
   remains significantly more expensive.

DVD-Video

   DVD-Video is a standard for storing video content on DVD media. As of
   2003, DVD-Video has become the dominant form of consumer video formats
   in the United States, Europe, and Australia.

   Though many resolutions and formats are supported, most consumer
   DVD-Video disks utilize either 4:3 or 16:9 aspect ratio MPEG-2 video,
   stored at a resolution of 720x480 ( NTSC) or 720x576 ( PAL). Audio is
   commonly stored using the Dolby Digital (AC-3) and/or Digital Theatre
   System (DTS) formats, ranging from monaural to 5.1 channel " Surround
   Sound" presentations. DVD-Video also supports features like 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 and sample rates.
   Compared with the CD format, the much higher capacity DVD format
   enables the inclusion of either considerably more music (with respect
   to total running time and quantity of songs) or far higher audio
   quality (reflected by higher linear sampling rates and higher vertical
   bit-rates, and/or additional channels for spatial sound reproduction).

   Despite DVD-Audio's superior technical specifications, there is debate
   as to whether or not the resulting audio enhancements are
   distinguishable to typical human ears. DVD-Audio currently forms a
   niche market, probably due to its dependency upon new and relatively
   expensive equipment.

Security

   DVD-Audio discs employ a robust copy prevention mechanism, called
   Content Protection for Prerecorded Media (CPPM) developed by the 4C
   group (IBM, Intel, Matsushita, and Toshiba).

   CPPM can be circumvented on a PC by capturing decoded audio streams in
   PCM format, but the underlying protection mechanism, encryption
   algorithms, and keys have not yet been cracked.

Players and recorders

   Modern DVD recorders often support additional formats, including
   DVD+/-R/RW, CD-R/RW, MP3, WMA, SVCD, JPEG, PNG, SVG, KAR and MPEG-4 (
   DivX/ Xvid). Some also include USB ports or flash memory readers. Many
   players are priced from under $/€ 25 and recorders from $/€ 50.

   DVD drives for computers usually come with one of two kinds of Regional
   Playback Control (RPC), either RPC-1 or RPC-2. This is used to enforce
   the publisher's restrictions on what regions of the world the DVD can
   be played. See Regional lockout.

Competitors and successors

   There are several possible successors to DVD being developed by
   different consortiums: Sony/Panasonic's Blu-ray Disc (BD), Toshiba's HD
   DVD and Maxell's Holographic Versatile Disc (HVD).

   The first generation of holographic media with 300 GB of storage
   capacity and a 160 Mbit/s transfer rate is scheduled for release in
   late 2006 by Maxell and its partner, InPhase.

   On November 18, 2003, the Chinese news agency Xinhua reported the final
   standard of the Chinese government-sponsored Enhanced Versatile Disc
   (EVD), and several patents for it. However, since then the format has
   generally failed to live up to expectations.

   On November 19, 2003, the DVD Forum decided by a vote of eight to six
   that HD DVD will be its official HDTV successor to DVD. This had no
   effect on the competing Blu-ray Disc Association's (BDA) determination
   that its format would succeed DVD, especially since most of the voters
   belonged to both groups.

   On April 15, 2004, in a co-op project with TOPPAN Printing Co., the
   electronics giant Sony Corp. successfully developed the paper disc, a
   storage medium that is made out of 51% paper and offers up to 25 GB of
   storage, about five times more than the standard 4.7 GB DVD. The disc
   can be easily cut with scissors and recycled, offering foolproof data
   security and an environment-friendly storage media.

   As reported in a mid 2005 issue of Popular Mechanics, it is not yet
   clear which technology will win the format war over DVD. HD DVD discs
   have a lower capacity than Blu-ray discs (15 GB vs. 25 GB for single
   layer, 30 GB vs. 50 GB for dual layer), but Blu-ray requires changes in
   manufacturing machinery and techniques and is thus more expensive.

   In April, 2000, Sonic Solutions and Ravisent announced hDVD, an HDTV
   extension to DVD that presaged the HD formats that debuted 6 years
   later.

   This situation—multiple new formats fighting as the successor to a
   format approaching purported obsolescence—previously appeared as the "
   war of the speeds" in the record industry of the 1950s. It is also, of
   course, similar to the VHS/Betamax war in consumer video recorders in
   the late 1980s.

   It is possible that neither Blu-ray, HD DVD, nor a next-generation
   optical recording products will succeed. The storage capacities of hard
   disk drives and solid-state memory have grown faster than those of
   optical discs (since CD's introduction year, 1983, storage capacity of
   HDDs grew by a factor of about 150,000, from 5 MB to 750 GB, while the
   capacity of Blu-ray is only 90 times larger than CD), and all three are
   much more capable of storing general consumer content —such as photos,
   music, and video— than in the past. Hard disk drives having a few
   terabytes of storage capacity will be on the market before 2008. A
   terabyte is equivalent to about 2000 CD-ROMs, 130 DVD-9s, or 20
   dual-layer BDs. However, hard disk drives and memory cards are at the
   moment hundreds of times more expensive than optical discs (US$50 or
   more compared to $0.50). The price per gigabyte of a hard disk drive,
   $0.40 ($200/500 GB), is growing closer to that of a DVD-ROM, $0.06
   ($0.50/8.5 GB); BD-ROM, $0.03 ($1.50/50 GB); recordable DVD-5, $0.10
   ($0.50/4.7 GB); or recordable DVD-9, $0.30 ($2.50/8.5 GB); and is lower
   than the cost of a BD-RE25, $1.20 ($30/25 GB). Direct access to large
   amounts of information is much more convenient with a hard disk drive.
   As broadband becomes fast enough (40 Mbit/s and higher) and more widely
   available, physical media will become less important as a distribution
   format.

   One last possibility is that DVD will not be replaced in terms of Home
   Theatre by any format currently developed. People may not be so keen to
   upgrade their DVD collection so (relatively) soon. DVD may remain the
   format of choice for many more years, which may lead to the creation of
   a better technology that will replace it.

   The new generations of optical formats have restricted access
   (anti-copy mechanisms), and it is therefore possible that consumers may
   ignore them.

   Retrieved from " http://en.wikipedia.org/wiki/DVD"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
