FREE HOST - www.000webhost.com

 

 

 

DVD

 

DVD

DVD-R read/write side

Media type:

Optical disc

Capacity:

4.7 GB (single layer), 8.5 GB (dual layer)

Usage:

Data storage, audio, video, games

 

 

 

 

Optical disc authoring
  • Optical disc
  • Optical disc image
  • Optical disc drive
  • Authoring software
  • Recording technologies
    • Recording modes
    • Packet writing

 

Optical Media Types

 
  • Laserdisc
  • Compact disc/CD-ROM: CD-R, CD-RW
  • MiniDisc
  • DVD: DVD-R, DVD-D, DVD-R DL, [[DVD+R]],
     [[DVD+R DL]], DVD-RW, [[DVD+RW]],
     DVD-RW DL, [[DVD+RW DL]], DVD-RAM
  • Blu-ray Disc: BD-R, BD-RE
  • HD DVD: HD DVD-R, HD DVD-RW, HD DVD-RAM
  • UDO
  • UMD
  • Holographic data storage
  • 3D optical data storage
  • History of optical storage media

 

Standards

 
  • Rainbow Books
  • File systems
    • ISO 9660
      • Joliet
      • Rock Ridge
        • Amiga Rock Ridge extensions
      • El Torito
      • Apple ISO9660 Extensions
    • Universal Disk Format
      • Mount Rainier

 

 

Size comparison: A 12 cm Sony [[DVD+RW]] and a 19 cm Dixon Ticonderoga pencil.

 

Size comparison: A 12 cm Sony [[DVD+RW]] and a 19 cm Dixon Ticonderoga pencil.

DVD (also known as "Digital Versatile Disc" and "Digital Video Disc") is a popular optical disc storage media format used for data storage. Its main uses are for movies, software, and data archiving. Most DVDs are of the same dimensions as compact discs (CDs) but store more than 6 times the data.

The term DVD is used in describing three ways that data is stored on the disks. DVD-ROM has data which can only be read and not written, DVD-R can be written once and then functions as a DVD-ROM, and DVD-RAM holds data that can be re-written multiple times.

DVD-Video and DVD-Audio discs respectively refer to properly formatted and structured video and audio content. Everything else, including other types of DVD discs with video content, is referred to as a DVD-Data disc. DVD is also used generically to refer to HD (High Density) video disc formats Blu-ray and HD DVD.

 

History

In the early 1990s two high-density optical storage standards were being developed; one was the MultiMedia Compact Disc, backed by Philips and Sony, and the other was the Super Density disc, 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 videotape format war between VHS, Betamax and Video 2000 in the 1980s.

Philips and Sony abandoned their MultiMedia Compact Disc and fully agreed upon Toshiba's SuperDensity Disc with only one modification, namely changing to 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. 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 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 official DVD specification documents have never defined DVD. Usage in the present day varies, with "DVD", "Digital Video Disc", and "Digital Versatile Disc" all being common.

 

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

7.96

12 cm, double sided

9.4

8.75

17.1

15.93

8 cm, single sided

1.4

1.30

2.6

2.42

8 cm, double sided

2.8

2.61

5.2

4.84

The 12 cm type is a standard DVD, and the 8 cm variety is known as a mini-DVD. These are the same sizes as a standard CD and a mini-CD, respectively.

Note: GB here means gigabyte, equal to 109 (or 1,000,000,000) bytes. Many programs will display gibibyte (GiB), equal to 230 (or 1,073,741,824) bytes.

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

Capacity Note: There is a difference in capacity (storage space) between + and - DL DVD formats. For example, the 12 cm single sided disk has capacities:

Disk Type

Sectors

bytes

GB

GiB

DVD-R SL

2,298,496

4,707,319,808

4.7

4.384

DVD+R SL

2,295,104

4,700,372,992

4.7

4.378

DVD-R DL

4,171,712

8,543,666,176

8.5

7.957

DVD+R DL

4,173,824

8,547,991,552

8.5

7.961

Capacity nomenclature

The five basic types of DVD are referred to by their approximate capacity in 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 on one side, single on other

DVD-14

Double sided, dual layer on both sides

DVD-18

Technology

Internal mechanism of a DVD-ROM Drive

 

Internal mechanism of a DVD-ROM Drive

DVD uses 650 nm wavelength laser diode light as opposed to 780 nm for CD. This permits a smaller spot on the media surface that is 1.32 µm for DVD while it was 2.11 µm for CD.

Writing speeds for DVD were 1x, that is 1350 kB/s (1318 KiB/s), in first drives and media models. More recent models at 18x or 20x will have 18 or 20 times that speed. Note that for CD drives, 1x means 153.6 kB/s (150 KiB/s), 9 times slower.

 

DVD Recordable and Rewritable

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 (minus/dash), +[[DVD+R|R]]/[[DVD+RW|RW]] (plus), -RAM.

 

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 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 semi-transparent layer. The layer change mechanism in some DVD players can show a noticeable pause, as long as two seconds by some accounts. This caused more than a few 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 comparable to that of single-layer drives, though the blank media remain more expensive.

 

DVD-Video

DVD-Video is a standard for storing video content on DVD media. In the U.S., weekly DVD-Video rentals first out-numbered weekly VHS cassette rentals in June 2003, illustrating the rapid adoption rate of the technology in the marketplace.

Though many resolutions and formats are supported, most consumer DVD-Video disks use either 4:3 or 16:9 aspect ratio MPEG-2 video, stored at a resolution of 720×480 (NTSC) or 720×576 (PAL). Audio is commonly stored using the Dolby Digital (AC-3), Digital Theater System (DTS) formats, ranging from monaural to 5.1 channel "Surround Sound" presentations, 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. 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 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).

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.

 

Competitors and Successors

There are several possible successors to DVD being developed by different consortia. Sony/Panasonic's Blu-ray Disc (BD) and Toshiba's HD DVD began to gain traction in 2007, and next-generation technologies such as Maxell's Holographic Versatile Disc (HVD) and 3D optical data storage are being actively developed.

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.