DVD (short for "bb digital video disc " or " digital versatile disc ") is a digital optical disc storage format developed and developed by Philips and Sony in 1995. The media can store all kinds of digital data and is widely used for software and other computer files as well as video programs watched using DVD players. DVDs offer higher storage capacity than compact discs while having the same dimensions.
Previously recorded DVDs are mass-produced using print machines that physically insert data into DVDs. The disc is a DVD-ROM form because the data can only be read and not written or deleted. Recordable blank DVD discs (DVD-R and DVD R) can be recorded once using a DVD recorder and then function as DVD-ROM. DVDs that can be rewritten (DVD-RW, DVD RW, and DVD-RAM) can be recorded and deleted many times.
DVDs are used in DVD-Video consumer digital video formats and in consumer audio format DVD-Audio as well as for writing DVD discs written in a special AVCHD format for storing high definition material (often in conjunction with AVCHD format camcorders). DVDs that contain other types of information can be referred to as DVD data discs.
Video DVD
Etimologi
The Oxford English Dictionary commented that, "In 1995 the rival manufacturer of a product that was originally named digital video disc agreed that, in order to emphasize the flexibility of formatting for multimedia applications, the preferred DVD abbreviation would be understood to show versatile discs digital. "The OED also stated that in 1995," The companies said the official name of the format would be only DVDs.Toshiba had used the name 'digital video disc', but it switched to 'digital versatile disc' after the computer company complained that it abandoned their application. "
"Digital versatile disc" is an explanation given in the DVD Forum Primer from 2000 and in the DVD Forum mission statement.
Maps DVD
History
Development
There are several formats developed to record video on optical discs before DVD. The optical recording technology was invented by David Paul Gregg and James Russell in 1958 and first patented in 1961. The format of consumer optical disc data known as LaserDisc was developed in the United States, and first came to market in Atlanta, Georgia in 1978. Used discs much larger than the next format. Due to the high cost of players and discs, consumer use of LaserDisc is very low both in North America and Europe, and is not widely used anywhere outside Japan and the more affluent regions of Southeast Asia, such as Hong Kong, Singapore, Malaysia. and Taiwan.
The Video CD released in 1987 used an analog video encoding on an optical disc that fit the standard 120 mm (4.7 inch) audio CD size. Video CD (VCD) became one of the first formats to distribute digital encoded movies in this format, in 1993. In the same year, two new optical disk storage formats are being developed. One is the Multimedia Compact Disc (MMCD), powered by Philips and Sony, and the other is the Super Density (SD) disk, powered by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson and JVC. By the time the press was launched for both formats in January 1995, the MMCD nomenclature had been dropped, and Philips and Sony referred to their format as Digital Video Disc (DVD).
Representatives of the SD camp asked IBM to ask for suggestions about the file system to use for their disks, and sought support for their formats for storing computer data. Alan E. Bell, a researcher from IBM's Almaden Research Center, got the request, and also learned about the MMCD development project. Fearful of being caught in the repetitive war of expensive videocassette formats between VHS and Betamax in the 1980s, he assembled a group of computer industry experts, including representatives from Apple, Microsoft, Sun Microsystems, Dell, and many others. This group is called the Technical Working Group, or TWG.
On August 14, 1995, an ad hoc group formed from five computer companies (IBM, Apple, Compaq, Hewlett-Packard, and Microsoft) issued a press release stating that they would only accept one format. TWG chose to boycott both formats unless both sides agreed on a convergent single standard. They recruited Lou Gerstner, IBM's president, to pressure executives from the warring factions. In a significant compromise, the MMCD and SD groups agreed to adopt the SD 9 proposal, which determined that the two layers of discs were layered from the same side - rather than the SD 10 proposal, which would create two sides. disks that users must submit. As a result, the DVD specification provides a storage capacity of 4.7 GB for single layer, single-sided and 8.5 GB disks for multilayered disks, one side. The DVD specification is almost identical to Toshiba and Matsushita's Super Density Disc, except the dual-layer option (MMCD is single-sided and optionally dual-layer, while SD is two and a half thick, single-layer discs are pressed separately and then taped to form disk two sides) and EFMPlus modulation designed by Kees Schouhamer Immink.
Philips and Sony decided that it was in their interest to end the format war, and agreed to unite with companies that support Super Density Disc to release a single format, with technology from both. After another compromise between MMCD and SD, the computer company via TWG won the day, and one format was approved. TWG also collaborated with the Optical Storage Technology Association (OSTA) on the use of the implementation of the ISO-13346 file system (known as Universal Disk Format) for use on new DVDs.
Adoption
Movie distributors and home entertainment adopted the DVD format to replace the ubiquitous VHS tapes as the mainstream consumer digital video distribution format. They embrace DVDs as they produce superior moving images and sounds, providing superior data age, and can be interactive. Interactivity in LaserDiscs has proven to be desired by consumers, especially collectors. When the LaserDisc price drops from about $ 100 per disk to $ 20 per disk in retail, this luxury feature becomes available for mass consumption. At the same time, the film studios decided to change their home entertainment release model from lease model to purchase model, and a large number of DVDs were sold.
At the same time, demand for talent and interactive design services has been created. Movies in the past have uniquely designed titles. Suddenly every movie released requires an information architecture and an interactive design component that fits the movie's tone and is at the level of quality that Hollywood demands for its products.
DVD as a format has two qualities at that time that are not available in other interactive media: capacity and speed enough to deliver full high quality video and sound, and low cost delivery mechanisms provided by consumer product retailers. Retailers will quickly move to sell their players under $ 200, and finally for under $ 50 in retail. In addition, the media itself is small enough and light enough to be sent using first class public stamps. Almost overnight, this creates new business opportunities and models for business innovators to re-create home entertainment distribution models. It also gives companies a cheap way to provide business and product information on full motion videos via direct mail.
Immediately after the formal adoption of unified standards for DVDs, two of the four leading video game console companies (Sega and The 3DO Company) said they already had plans to design game consoles with DVDs as source media. (Sony, although one of the DVD format developers and finally the first company to actually release a DVD-based console, declared at the time that they were not planning on using the DVD in their gaming system.) Game consoles like PlayStation 2, Xbox, and Xbox 360 use DVD as source medium for games and other software. Contemporary games for Windows are also distributed on DVD.
Specifications
The DVD specifications created and updated by the DVD Forums are published as so-called DVD Books (eg DVD-ROM Books, DVD-Audio Books, DVD-Video Books, DVD-R Books, DVD-RW Books, DVD-RAM Books, DVD-AR Books, DVD-VR Books, etc.).
Several specifications for the mechanical, physical and optical characteristics of DVD optical discs can be downloaded as a standard available for free from the ISO website. There are also European Computer Manufacturers Association (Ecma) standards that are equivalent to some of these specifications, such as the Ecma-267 for DVD-ROM. Also, DVD RW Alliance publishes DVD recordable specifications such as DVD R, DVD R DL, DVD RW or DVD RW DL. This DVD format is also ISO standard.
Some DVD specifications (for example DVD-Video) are not publicly available and can only be obtained from the DVD/Logo Licensing Corporation Format at a cost of US $ 5000. Each customer must sign a confidentiality agreement because certain information in the DVD Book is exclusive and confidential.
DVD can be recorded and rewritten
HP initially developed DVD media that could be recorded from the need to store data for backup and transportation. Recordable DVDs are now also used to record consumer audio and video. Three formats developed: DVD-R/RW, DVD R/RW (plus), and DVD-RAM. DVD-R is available in two formats, General (650Ã, nm) and Authoring (635 nm), where the Authoring disc can be recorded with CSS encrypted video content but the General disk should not be.
Although most current DVD writers can write DVD R/RW and DVD-R/RW formats (usually denoted by "DVDÃ, Â ± RW" or the presence of both the DVD Forum logo and the DVD RW Alliance logo), "plus" and the " dash "using different writing specifications. Most DVD readers and players play both types of disks, although older models may experience problems with "plus" variants.
Some first generation DVD players will cause damage to DVDÃ, Â ± R/RW/DL when trying to read it.
The spiral groove forming the encoded DVD structure encodes an irreversible identification data known as the Media Identification Code (MID). MID contains data such as manufacturer and model, byte capacity, allowed data rate (also known as speed), etc.
Dual-layer recording
Dual-layer recording (sometimes also known as double-layer recording) allows DVD-R and DVD R discs to store significantly more data - up to 8.5 gigabytes per disk, compared to 4.7 gigabytes for single-layer disc. Along with this, DVD-DL has slower write speeds than regular DVDs. When played, a slight transition can sometimes be seen in playback when the player changes the layer. DVD-R DL developed for DVD Forum by Pioneer Corporation; DVD R DL was developed for DVD RW Alliance by Mitsubishi Kagaku Media (MKM) and Philips.
Double layer disks differ from one counterpart by using the second physical layer in the disk itself. Dual layer capability drives access the second layer by irradiating the laser through the first semitransparent layer. In some DVD players, layer changes can show a real pause, up to a few seconds. This caused some viewers to worry that their dual-layer discs were damaged or damaged, with studio end results starting to create a standard message list explaining the dual layer stop effect on all double layer disk packs.
DVD recordable discs that support this technology backwards compatible with some DVD players and DVD-ROM drives available. Many current DVD recorders support dual-layer technology, and the price is now comparable to single-layer drives, although the empty media remains more expensive. The speed of recording achieved by dual-layer media is still far below the single media layer.
Dual layer DVDs are recorded using Opposite Track Path (OTP). DVD-ROM CDs that are controlled for computer use are produced with track 0 starting from inside diameter (as is the case with one layer). Trace 1 then starts on the outside diameter. DVD video disks are controlled slightly differently. The video is split between layers so that layer 1 can be made to start at the same diameter as layer 0 is completed. This accelerates the transition when the layer changes because although the laser has to refocus on layer 1, it does not have to pass through the disc to find it.
Capacity
The basic types of DVDs (12 cm in diameter, one side or two homogeneous sides) are referenced by a rough estimate of their capacity in gigabytes. In the draft version of the specification, DVD-5 does have five gigabytes, but some parameters are changed later as described above, so the capacity decreases. Other formats, those with a diameter of 8 cm and a hybrid variant, obtained the same numerical name with a larger deviation.
Type 12 cm is a standard DVD, and 8 cm varieties known as MiniDVD. These are the same size as standard CDs and mini CDs, respectively. Capacity based on surface area (MiB/cm 2 ) varies from 6.92 MiB/cm 2 in DVD-1 to 18.0 MB/cm 2 on DVD-18.
Each DVD sector contains 2,418 bytes of data, 2,048 bytes which is user data. There is a small difference in storage space between the and - (hyphen) formats:
DVD drive and player
DVD drives are devices that can read DVD discs on a computer. DVD players are a specific type of device that does not require a computer to work, and can read DVD-Video and DVD-Audio discs.
Laser and optics
The three general optical disc media (Compact disc, DVD, and Blu-ray) use light from the laser diode, for spectral purity and the ability to be precisely focused. DVDs use wavelength 650 n (red), compared to 780 n nm (far-red, commonly called infrared) for CDs. This shorter wavelength allows smaller holes in the media surface compared to CDs (0.74 Âμm for DVD versus 1.6 Âμm for CDs), partly accounting for an increase in DVD storage capacity.
In comparison, Blu-ray Disc, DVD format router, uses a 405 nm (purple) wavelength, and one dual-layer disc has a storage capacity of 50 GB GB.
Transfer rate
Read and write speeds for the first DVD drive and player are 1,385 kB/s (1,353 KiB/s); This speed is usually called "1ÃÆ'â €" ". The newer model, at 18Æ'â € "or 20ÃÆ'â €", has 18 or 20 times that speed. Note that for CD drives, 1ÃÆ'â € "means 153.6 kB/s (150Ã, KiB/s), about 1/9 as fast.
DVD-Video
DVD-Video is the standard for distributing video/audio content on DVD media. This format went on sale in Japan in 1995, in the United States, Canada, Central America, and Indonesia in 1997, and in Europe, Asia, Australia and Africa in 1998. DVD-Video became the dominant form of home video distribution in Japan when it first went on sale in 1995, but shared the market for home video distribution in the United States until June 15, 2003, when weekly DVD-Video in the United States lease began to exceed the number of weekly VHS tape rentals. DVD-Video is still the dominant form of worldwide home video distribution except in Japan where it is surpassed by Blu-ray Discs when the first Blu-ray went on sale in Japan on March 31, 2006.
Security
Content Scramble System (CSS) is a digital rights management (DRM) and encryption system used on almost all commercially produced DVD-video disks. CSS uses a proprietary 40-bit flow cipher algorithm. This system was introduced around 1996 and was first compromised in 1999.
The purpose of CSS is twofold:
- The CSS prevents a byte-to-byte copy of the MPEG stream (digital video) from being able to play because the copy does not include a hidden key in the prospect area of ​​a restricted DVD.
- CSS gives manufacturers a reason to make their device conform to industry-controlled standards, since CSS scrambled discs are principally unplayable on non-compliant devices; anyone who wants to build a suitable device must obtain a license, which contains the requirement that the rest of the DRM system (area code, Macrovision, and user operating restrictions) be implemented.
Although most CSS decryption software is used to play DVD videos, other parts of the software (such as DVD Decrypter, AnyDVD, DVD43, Smartripper, and DVD Shrink) can copy DVDs to hard drives and remove Macrovision, CSS encryption, area code and restrictions user operation.
Consumer restrictions
The advent of filesharing has prompted many copyright holders to display notices on DVD packaging or display on screen when content is playing that warns consumers about the illegality of using a particular DVD. It is common to include a 90-second ad alert that most copying of contents is illegal. Many DVDs prevent skipping past or fast forwarding via this warning.
The arrangements to rent and borrow differ by geography. In the US, the right to resell, lease, or lend purchased DVDs is protected by the first sales doctrine under the Copyright Act of 1976. In Europe, leases and borrowing rights are more limited, under the 1992 European Guidelines that give the copyright holder the more broadly to limit commercial leasing and public borrowing of DVD copies of their work.
DVD-Audio
DVD-Audio is the format for delivering high quality audio content on DVD. It offers many channel configuration options (from mono to 5.1 surround sound) at various sampling frequencies (up to 24-bit/192Ã, Â ± kHz versus CDDA's 16-bit/44.1Ã, kHz). Compared to the CD format, DVD format with much higher capacity allows for much more music inclusion (in terms of total running time and track quantity) or much higher audio quality (reflected by higher sampling rates, sample resolution larger and additional channels for spatial sound reproduction).
DVD-Audio briefly forms a niche market, probably because it is very similar to format wars with rival SACD that DVD-Video avoided.
Security
DVD-Audio discs use a DRM mechanism, called Content Protection for Prerecord Media (CPPM), developed by the 4C group (IBM, Intel, Matsushita, and Toshiba).
Although CPPM should be much more difficult to solve than DVD-Video CSS, it's also finally cracked, in 2007, with the release of the dvdcpxm tool. The next libdvdcpxm library release (based on dvdcpxm) allows the development of an open source DVD-Audio player and software robbery. As a result, making a 1: 1 copy of DVD-Audio discs is now possible with relative ease, such as DVD-Video discs.
Successor and descending
In 2006, two new formats called HD DVD and Blu-ray Disc were released as DVD successors. HD DVD did not compete successfully with Blu-ray Disc in the 2006-2008 format war. Dual HD DVD layers can hold up to 30 GB and a double layer Blu-ray disc can store up to 50 GB.
However, unlike previous format changes, for example, vinyl to Compact Disc or VHS video cassette to DVD, there is no direct indication that standard DVD production will gradually diminish, as it still dominates, with about 75% of video sales and about one billion sales DVD players worldwide on April 3, 2011. In fact, experts claim that DVDs will remain the dominant medium for at least the next five years because Blu-ray technology is still in the introductory phase, writing and reading speeds are bad and hardware required to be expensive and not available.
Initially consumers are also slow to adopt Blu-ray because of the cost. In 2009, 85% of stores sold Blu-ray Discs. High definition television and an appropriate connection cable are also required to utilize Blu-ray discs. Some analysts suggest that the biggest obstacle to replacing DVDs is because of their installed base; most consumers are satisfied with the DVD. DVD works because it offers an interesting alternative to VHS. In addition, uniform media sizes allow manufacturers to create Blu-ray players and now format off compatible HD DVD players backwards, so they can play older DVDs. This is different from changes from vinyl to CD, and from tape to DVD, which involves a complete change in the physical medium. In 2012, it is still commonplace for studios to issue major releases in "combo package" formats, including DVDs and Blu-ray discs (and, in most cases, third disks with official digital copies). Also, some multi-disk devices use Blu-ray for key features, but DVDs for additional features (for example including the Harry Potter "Ultimate Edition" collection, 2009 preview release in 1967 The Prisoner TV series, and the 2007 collection related to Blade Runner ). Another reason cited (July 2011) for a slower transition to Blu-ray from DVD is the necessity and confusion over "firmware updates" and requires an internet connection to update.
This situation is similar to the turn of 78 rpm recorded lacquers to 45 rpm and 33 1/3 rpm vinyl recording. Since the new and old media are almost identical (disks on the turntable, played with a needle), the phonograph player player continues to include the ability to play 78s for decades after the format has been discontinued.
Manufacturers continue to release standard DVD titles in 2018, and their preferred format remains for the release of older television and movie programs. Some programs, such as Star Trek: The Original Series and Star Trek: The Next Generation, have to be re-scanned to produce a high-definition version of the original movie recording. (Certain specific effects are also updated to perform better in high-definition.) In the case of Doctor Who , a series mainly produced on standard definition video cassettes between 1963 and 1989, BBC Videos reported intended to continue releasing DVD Release releases from the series until at least November 2013. The Netflix DVD service, started in 1998, still sends DVDs and Blu-ray to over 4 million subscribers.
DVDs also face competition from video on demand services. With the growing number of homes with high-speed Internet connections, many people now have the option to rent or buy videos from online services, and view them by streaming directly from the service server, meaning that customers need not have a permanent form of storage media for video at all. PWC predicts that online streaming revenue will overtake physical media sales revenue by 2018. Globally, the combined total revenue from over-the-top (OTT)/streaming services and on-demand video on demand (VOD) services is expected to grow at CAGR 19, 9% to take over physical home video revenue (DVD and Blu-ray sales and rentals) by 2018. By 2017, the digital streaming service has surpassed DVD and Blu-ray sales for the first time.
Longevity
The DVD life is measured by how long the data remains readable from the disk, assuming a compatible device exists that can read it: that is, how long the disk can be stored until the data is lost. Many factors affect longevity: composition and quality of media (recording and substrate layers), moisture and light storage conditions, initial recording quality (which is sometimes a matter of media compatibility and recorder), etc. According to NIST, "[a] temperatures of 64.4 °, Â ° F (18 ° C) and 40% RH [Relative Humidity] will be considered suitable for long-term storage, lower temperatures and RH are recommended for long-term storage. "
According to the Association of Optical Storage Technology (OSTA), "Manufacturers claim life spans ranging from 30 to 100 years for DVD, DVD-R, DVD R, and up to 30 years for DVD-RW, DVD RW and DVD-RAM."
According to the NIST/LoC research project conducted in 2005-2007 using accelerated life testing, "There were fifteen DVD products tested, including five DVD-Rs, five DVD Rs, two DVD-RWs and three DVD RW types. for each product. [...] Overall, seven of the tested products have estimated life expectancy under ambient conditions over 45. Four products have estimated life expectancy of 30-45 years in ambient storage conditions have an estimated life expectancy of 15 -30 years and two products have predicted life expectancy of less than 15 years when stored in ambient conditions. "The life expectancy for the 95% estimated survival in this project by product type is tabulated below:
See also
References
Further reading
External links
- All About Conversion From Multiple Video Format To DVD on Wikibooks
- DVD in Curlie (based on DMOZ)
- Dvddemystified.com: Frequently Asked Questions and Answers DVD
- Double Layer Explained - Information Guide for Double Layer Recording Process
- YouTube "DVD Gallery": 1997 DVD disc DVD Toshiba (segment) - Toshiba demo disc in store with technical information about "new" DVD format.
Source of the article : Wikipedia
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