A DVD is a Optical disk used for the data storage, in particular the Vidéo Numérique.

Denomination

Initials DVD meant in the beginning “DIGITAL Video Disc” , that is to say “disc digital video”.

Thereafter, of the manufacturers tried to popularize, by Retro-acronymie, the denomination “DIGITAL Versatile Disc” , that is to say “general-purpose numerical disc”.

Finally, the DVD Forum decided in 1999 that the standard is composed of these three simple letters.

Description and history

Physically, the DVD have practically same appearance as the CD since their dimensions are the same ones (a disc 120 millimetres in diameter or less often of 80 millimetres).
However on the technical plan, the principal differences lie in the format of encoding employed and the density of the information registered on the disque.
The used laser uses a wavelength of 635 or 650 Nm for a numerical opening of 0,60, which allows a variation of track of 740 Nm and a minimal length of cell of 400 Nm, the diameter of the laser spot being of 650 Nm.

Born in 1995, it was essential on the place of the cassette VHS, and that for several reasons:

  • facilitated use and flexibility of use: no rewinding contrary to the cassettes, possibility of reaching directly a precise point of film, chapitrage, access to no-claims bonus; possibility of seeing film in various languages with or without subtitling.
  • quality of the much higher image, and especially stability of this image: the images on VHS are very quickly degraded after only some readings;
  • one can store seven times there more data than on CD (either 4,7 Go or 4,38 Gio), and more still if the DVD is in double-layer;
  • the price of the engravers and consumable virgins (the DVD in itself) is relatively low; the simplicity of manufacture, compared to a Video tape recorder and its consumable, make of them instruments less expensive, more reliable and more robust than their predecessors;
  • the profit of space, if it is not a fundamental reason of the rise of the DVD, does not remain about it less one fundamental advantage for the user having a large collection of DVD.

The DVD marked the beginning of a new era in the cinema with the house. At the time of the VHS, the cinematographic amateur found generally only film itself on the cassette and, more rarely, of the no-claims bonus of very restricted number. Moreover, it can taste on the same support with the original version and the version in its language, with or without sous-titrage.
From now on, one can find in addition to the film which is of enough good quality, the trailers, of the making-of, of the interviews and even sometimes of the plays. One also finds on support DVD in the musical concerts, the series television, the videos Clip S, the spectacles of humorists, the meetings of gym, etc

Uses of the DVD

Types of applications of the DVD:
  • DVD-Video (containing films (video and its)) ;
  • DVD-Audio (container of its high-definition);
  • DVD-VR (container of the video or the recorded sound, usually since the TV or a video camera);
  • DVD+VR (an alternative of the DVD-VR used on discs +R and +RW);
  • DVD-ROM (computer data: Operating systems, applications, Encyclopedia S, Video games (PlayStation 2, Xbox, Xbox 360, GameCube, Wii, PC). The low costs and the great capacity of the DVD make of them Mass memories ideal (see the other types of mass memories on the right of this paragraph).
  • DVD-RAM (format of rewriteable DVD, as well as DVD+/-RW, whose principal asset is that it makes it possible to connect readings and writings by chance)

Video DVD

The video DVD were an enormous success these last years. They gradually replaced the cassettes VHS by offering a certain number of advantages compared to these last:

The quality of image is clearly improved, more especially as it does not worsen with the wire of the readings as it was the case with the video cassettes. Although many resolutions and formats are supported, the majority of the DVD to the detail use a format compressed MPEG-2 of ratio 4:3 or 16:9, stored with a resolution of 720×480 (NTSC) or 720×576 (STAKE). This video format makes it possible to preserve an image very well defined.

The DVD supports several Codecs audio (PCM, dolby AC 3 or SDR) and the Codage audiophonic contrary to the VHS) which records the sound in Frequency modulation on two tracks.

Often, the video DVD also propose the choice between several audio tracks making it possible to see a film in different Langue S and often give access to functions up to now new such as the choice between several Sous-titrage S, the access to no-claims bonus (cut scenes, comments of the realizer, slides of turning) and even sometimes the choice between several angles on certain films.

Compared to the cassette, one of the most notable innovations is the direct passage to a precise sequence: more need to rewind or seek a sequence as with a band: the direct support on one or more keys gives access contents or a chapter immediately.

Audio DVD and SACD

Appeared more recently, in the succession with the CD audio: two formats, the Audio DVD and the SACD (Super Audio CD). It is necessary to have a turntable specifically adapted to the one of these formats. For the moment, none of the two competitor supports manages to take a significant share of the market to succeed audio CD. For the general public, the difference in quality to listening is not enough significant to justify new investments.

Protection anti-copy of the DVD

With the creation of the format DVD, all was made to prevent from copying them:
  • the system Macrovision prevents the copy of a DVD towards a Magnétoscope;
  • the system CS prevents the copy of data of a DVD towards a computer.

But all these protective systems did not resist very a long time and there exists today a multitude of software allowing of “ripper” a DVD towards a PC to copy it either with the original format (identical quality but requires much space on the Hard drive), or with the format DivX or VCD (which then makes it possible to copy it from simple traditional CD realizing a deterioration of the quality). The majority of recent readers DVD are thus from now on “compatible DivX”.

Commercial protections by zones

The industrialists also conceived a system of zones being used mainly to limit exports of discs apart from the indicated areas, which makes it possible to the editors individually to keep control on the selling price on each area of the sphere.

However, there exist now readers being able to read discs of all the zones. It is in particular the case of the majority of the readers of DVD for computer. Moreover, it is always possible to have several readers, one by zone or quite simply to make “to dézoner” its reader.

Formats

Note: the manufacturers, supporting such or such standards and their specifications would be welcome.

There exist various formats of DVD, with for each one, of the different supports:

  • DVD-ROM : they are generally “in a hurry” i.e. there exists a basic matrix which is used as mould for the copies, and thus they are not recordable.

  • DVD-R : also noted - R (for Recordable : recordable) this standard is the first to have been born and was mainly intended for the video. The information safeguarded on the support is it by deterioration of an inscribable layer using the Laser of the engraver. The DVD-Forum is charged to promote the DVD-R (List of the members of the DVD-Forum).

  • DVD+R : as for - R but the standard more recent and is adapted than it - the R for the Data storage. It allows video visualization constantly, without “finalization” of the disc. It has as better features as his cousin. There does not exist however almost any difference visible with the naked eye between - R and the recent +R. Plus, the +R was however, in 2004, a little less compatible with readers DVD of living room (except those of Philips, active promoter of the DVD+) and the PC. The Consortium DVD+RW Alliance is charged to promote the DVD+R (appeared well after the DVD+RW). Although this one gathers less members than the DVD-Forum (originally three: Philips, Sony, HP), he is considered as being more “prestigious”.

  • DVD-R DLL , DVD-RW DLL , DVD+R DLL and DVD+RW DLL , still very few on the market, appear little by little. Dual DLL meaning “To bush-hammer” is “English double-layer”, these DVD offer a doubled capacity: 8,5 Go . However, one can note a light advance of the formats + , because the capacity to engrave the " DVD+R\RW DL" was implemented quite front on the engravers, maximum speed is currently also higher.

  • DVD-RW and DVD+RW : i.e. the rewriteable ones ( ReWritable ) with the same characteristics are hanging CD-RW as their counterparts - R and +R. the information saved on the support are it by reorganization of the recordable layer using the Laser of the engraver. This is why a formatting is necessary before writing or to erase the disc.

  • DVD-RAM : Normalizes not very widespread, more expensive, but being able to contain up to 9,4 Go (compared to 4,7 for the preceding models). They are rewriteable like the DVD+RW and the DVD-RW but support more cycles of writing than the latter. They were at their beginnings contained in a protective cartridge.

These various formats created a certain confusion. In 2005, new types of engravers make it possible to record under several formats.

Storage capacity

The rated capacities of the DVD are given in gigaoctets (1 Go =: 1,000,000,000 bytes) but the majority of the programs indicate the sizes in gibioctets (1 Gio =: 1,073,741,824 bytes). There exists at the beginning 4 types of DVD:
  • the DVD-5: it is composed of a face and a layer of storage. Its capacity is of 4,7 Go or 4,38 Gio.
  • the DVD-9: it is composed of a face and two layers of storage. Its capacity is of 8,5 Go or 7,92 Gio.
  • the DVD-10: it is composed of two faces and a layer by face (it is necessary to turn over the DVD to be able to read the second face). Its capacity is of 9,4 Go or 8,76 Gio.
  • the DVD-18: it is composed of two faces and two layers per face. Its capacity is of 17 Go or 15,84 Gio.

Currently, DVD of the trade (films, concerts…) are very often DVD-9 because their capacity allows an encoding more high banc providing a better sound quality and visual that the DVD-5. But there exists now the DVD+R 9 (which offers 8,5 Go of storage capacity) for the private individuals who wish to engrave their clean vidéos.

Personalization

The personalization of the face of presentation of DVD was left a long time with printable self-adhesive kits, to affix on the disc.

Certain printers as make it possible to print directly on the discs, in conditions as those are equipped with a printable surface (white or silver plated).

The manufacturers are leaning on the question of a single material allowing to meet this need. In 2000, Yamaha had tried the blow of the DiscT@2 (Pronounce DiscTatoo ) making it possible to engrave images on the surface not used during the engraving of the data. In 2005 HP makes the advertisement of the technology LightScribe which allows, by having the compatible engraver and discs, to print texts and images on the face of presentation of the disc, without resorting to ink. Nec proposes of sound with dimensions a similar technology called LabelFlash . For the moment, these solutions of engraving of label (or Certification ) are all only Monochrome S. technology Lightscribe is most widespread today.

To come

  • to succeed the DVD, two formats are in competition: the Disc Blu-ray (its basic capacity is of 25 Go and passes to 50 Go in double-layer) and HD-DVD (15 Go in simple layer, 30 Go in double-layer, even 45 Go in triple sleep). The HD-DVD was approved right now by the DVD Forum (authority in charge of the development and the promotion of format DVD) like successor of format DVD. It is probable that these two formats will cohabit during a few years on the market.
  • HVD ( Changeable Holographic Disc or General-purpose Holographic Disc ) is him also already ready, although it is not yet at the commercial stage. It has a capacity of several terabytes.
  • Dualdisc
  • the FVD (Changeable Forward Disc) is an alternative format in Blu-Ray and the HD-DVD pushed by the government Taiwan board. The idea is to propose a format of optical disk allowing the high-definition at a price less low than the two giant formats. This result is obtained by slightly increasing the capacity of the disc until 5,4 Go in simple layer and 9,8 Go in double-layer (triple layer is possible also), but by always reading it with a red laser. The use of a codec more powerful than the MPEG-2, WMV 9 makes it possible to have until 135 minutes of film in high-definition to the format 720p on a disc double-layer and in 1080i on a triple disc sleep.

Software of creation of DVD-Audio

The traditional software of creation of DVD very often does not support the DVD Audio. There thus exist dedicated software:

For Mac Os X

The operating softwares Tiger and Leopard are sufficed for them even for engraving to DVD

For Windows

  • Cirlinca DVD-AUDIO Solo

  • Steinberg WaveLab: Good quality also for this software.
  • audio Minnetonka DiscWelder Bronzes, Steel and Chrome II (with SurCode MLP)
  • DigiOn Audio 2
  • Sonic Sonic Studio HD and DVD-Audio Creator
  • Gear Pro Mastering Edition

For Linux

  • an DVD-Audio project exists and provides a whole of software which makes it possible to engrave an DVD-Audio.

Manufacturers of engravers

Engravers more and more are found. Here some companies which produce engravers:

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