DVD

The DVD is a type of optical disc for data storage. The acronym DVD stands for Digital Versatile Disc (Digital Versatile Disc), so the acronyms in Spanish and English coincide. In its beginnings, the middle “V” referred to video (Digital Video Disc or Digital Video Disc), due to its development as replacement of the VHS format for video distribution to homes.

The DVD standard emerged in 1995 Consortium (DVD Consortium).

The DVD drive is the device that refers to the multitude of ways data is stored: DVD-ROM (read-only device), DVD-R, and DVD+R (allow recording only once), DVD-RW and DVD+RW (allow recording and then erasing). They also differ in the storage capacity of each of the types.

As the DVD format gained popularity since the 2000s, the term "DVD" colloquially to refer to a film released in this format; for example the expression "watch a DVD" describes the act of watching a movie in this format. The Royal Spanish Academy defines the term "DVD" as much as the optical support that contains the data as well as the recording or reading device of this format.

History

In the early 1990s, two high-density optical storage standards were being developed:

1. the multimedia compact disc (MMCD), supported by Philips and Sony;
2. the super density (SD), supported by Toshiba, Time Warner, Panasonic, Hitachi, Mitsubishi Electric, Pioneer, Thomson and JVC.

Philips, Sony and Panasonic got together, and agreed with Toshiba to adopt SD, but with a modification: the adoption of Philips' EFM Plus, created by Kees Immink, which despite being 6% less efficient than the system Toshiba encoding (hence the capacity is 4.7 GB instead of the 5 GB of the original SD), it has the great advantage that EFM Plus has great resistance to physical damage to the disk, such as scratches or footprints. The result was the creation of the DVD Consortium, founded by the above companies, and the DVD version 1.5 specification, announced in 1995 and finalized in September 1996. In May 1997, the The DVD Consortium was replaced by the DVD Forum with the following members:

• Hitachi, Ltd.
• Panasonic Corp
• Mitsubishi Electric Corporation
• Pioneer Electronic Corporation
• Royal Philips Electronics N.V.
• Sony Corporation
• Thomson
• Time Warner Inc.
• Toshiba Corporation
• Victor Company of Japan, Ltd. (JVC)

The DVD Forum created the official standards:

• DVD-ROM
• DVD-R
• DVD-RW
• DVD-RAM

DVD+RW Alliance created other standards (to avoid paying the license to the Forum):

• DVD+R
• DVD+RW

Since DVD+R/RW discs are not part of the official standards, they do not display the official "DVD" logo. Instead, they carry the "RW" logo even though they are write-once discs, which has caused some controversy in some quarters as deceptive advertising, as well as confusing users.

Technical information

PlayStation 2, the first video game console that used this format.

DVDs fall into two categories: single layer and dual layer. In addition, the disc can have one or two sides, and one or two layers of data for each side; the number of sides and layers determines the capacity of the disc. Double-sided formats are rarely used outside of the DVD-Video realm.

Single-layer DVDs can store up to 4.7 gigabytes according to manufacturers in decimal base (International System Unit), and approximately 4.38 gigabytes or in binary base (ITC unit), about seven times more than a standard CD. It uses a reading laser with a wavelength of 650 nm (in the case of CDs, it is 780 nm) and a numerical aperture of 0.6 (compared to 0.45 for CDs); read resolution is increased by a factor of 1.65. This is applicable in two dimensions, so the actual physical data density is increased by a factor of 3.3.

DVD uses a more efficient encoding method in the physical layer: the error detection and correction systems used in CD, such as CRC cyclic redundancy check, Reed Solomon - Product Code (RS-PC), as well as Eight-to-Fourteen Modulation (EFM) line coding, which was replaced by a more efficient version, EFM Plus, with the same characteristics as the classic EFM. The CD subcode was removed. As a result, the DVD format is 47% more efficient than CD-ROM, which uses a third layer of error correction.

Unlike compact discs, where sound (CDDA) is stored in a fundamentally different way than data, a properly created DVD will always contain data following the UDF and ISO 9660 file systems.

Types of DVDs

DVDs can be classified:

• According to its content:

View of DVD-Video files in the file manager in the VIDEO_TS folder with a single level disk menu.

• • DVD-Video: movies (video and audio).
  • DVD-Audio: High fidelity audio. For example: 24 bits per sample, 48 kHz sampling speed and a dynamic range of 144 dB.^{[chuckles]required]}
  • DVD-Data: all types of data.

Inside a DVD recorder recording a record.

• According to their re-recording capacity (Most new DVD recorders can record in both formats and carry both logos, "+RW" and "DVD-R/RW"):
  • DVD-ROM: only reading, manufactured with press.
  • DVD-R and DVD+R: recordable once. The difference between the +R and -R types lies in the form of recording and encoding the information. In the +R holes are 1 logical while in the –R holes are 0 logical.
  • DVD-RW and DVD+RW: rewrapped.
  • DVD-RAM: Random Access Irrigable. It performs a check on the integrity of the data always active after completing the writing.
  • DVD+R DL: one-time double-layer.
  • The DVD-ROM stores from 4.7 GB to 17 GB.
• According to their number of layers or faces:
  • DVD-5: one face, simple layer; 4.7 GB or 4.38 GiB. Discos DVD±R/RW.
  • DVD-9: one face, double layer; 8.5 GB or 7.92 GiB. DVD+R DL discs. Dual-layer recording allows DVD-R discs and DVD+RW to significantly store more data, up to 8.5 GB per disk, compared to 4.7 GB that allow one-layer discs. DVD-R DL (dual layer) were developed for DVD Forum by Pioneer Corporation. DVD+R DL was developed for the DVD+R Alliance by Philips and Mitsubishi Kagaku Media. A double-layer disc differs from a conventional DVD in which it uses a second physical layer located inside the disk. A double-layered reading unit accesses the second layer by projecting the laser through the first semi-transparent layer. The layer change mechanism on some DVDs can lead to a pause of up to a couple of seconds. Recordable disks support this technology by maintaining compatibility with some DVD players and DVD-ROM drives. Many DVD recorders support dual-layer technology, and its price is comparable to one-layer units, although the medium remains considerably more expensive.
  • DVD-10: two faces, simple layer on both; 9,4 GB or 8,75 GiB. Discos DVD±R/RW.
  • DVD-14: two faces, double layer on one, simple layer on the other; 13,3 GB or 12,3 GiB. Rarely used.
  • DVD-18: two faces, double layer on both; 17,1 GB or 15,9 GiB. DVD+R discs.
  • There are also 8 cm DVDs that are called miniDVD (not confusing with cDVD, which are CDs containing video DVD type information) that have a capacity of 1.5 GB.

Speed

The data transfer speed of a DVD drive is given in multiples of 1350 KB/s.

Internal mechanism of a DVD-ROM drive.

Early CD and DVD drives read data at a constant speed (constant linear velocity or CLV). The data on the disk passed under the reading laser at a constant speed. Since the linear speed (meters/second) of the track is greater the further away it is from the center 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. Currently, most CD and DVD drives have a constant rotation speed (constant angular velocity or CAV). The maximum data transfer rate specified for a certain drive and disk is achieved only at the ends of the disk. Therefore, the average speed of the drive is equal to 50-70% of the maximum speed for the drive and the disk. Although this may seem like a drawback, such drives have a shorter seek time, since they never have to change the disk's rotation speed.

DVD-ROM unit.

File system

DVDs follow the universal disk format (UDF) and Joliet file system. This file system was adopted to replace the ISO 9660 standard, and its main use is recording or rewriting discs. It was developed by OSTA (Optical Storage Technology Association, Optical Storage Technology Association).

Publication (regions)

Codes of DVD region in the world.

DVD region codes are a digital rights management technique designed to allow film distributors to control aspects of a work, including content, release date and price, according to the region.

This is accomplished by locking DVD players so that they can only play DVDs encoded for their region (in addition to DVDs that have no region code at all). In practice, many DVD players allow you to play discs from any region, or can be modified for that purpose.

DVDs can use one code, a combination of codes (multi-region), all codes (all regions), or no codes (region free).

• 0: Multiregion.
• 1: North America (except Mexico and Greenland) and American territories (including Puerto Rico), and Bermuda.
• 2: Central and Western Europe, Western Asia, Egypt, South Africa, Japan, territories of European countries, French Guiana and Greenland.
• 3: South-East Asia and South Korea.
• 4: Mexico, Central America, Latin America (except French Guiana), Antilles and Oceania (except New Caledonia).
• 5: Africa (except South Africa and Egypt) and North, Central and Southern Asia.
• 6: China.
• 7: Reserved for future use.
• 8: International travel such as airplanes, cruises, etc.

DVD predecessors

• CD-ROM
• VHS (He stopped selling in most of the world in 2005 and worldwide in 2016)
• Beta
• Laserdisc

Successors to DVD

• HD DVD, (which was discontinued in 2008)
• Disco Blu-ray
• HVD
• Archival Disc

DVD today

Movies and DVD series available in a library.

In the 2000s, two new formats called HD DVD and Blu-ray Disc were released as successors to DVD. HD DVD competed unsuccessfully with Blu-ray Disc in the 2006–2008 format war. A double layer HD DVD can store up to 30 GB and a double layer Blu-ray disc can store up to 50 GB.

Evolution of the price of the DVD.

Take MB on DVD.

Cost of reading and writing devices on DVD.

Unlike previous format changes, however, such as vinyl and cassette to compact disc or VHS videotape to DVD, there is no immediate indication that standard DVD production will slow down, as it is still dominate, with around 75% of video sales and approximately one billion DVD player sales worldwide as of April 2011. In fact, experts say DVD will remain the dominant medium for at least minus another five years, as Blu-ray technology is still in its introductory phase, read and write speeds are slow, and the necessary hardware is expensive and not readily available. For similar reasons a later technology, Ultra HD Blu-ray recorded little interest and low sales upon its introduction.

Modern UHD televisions have climbing technologies to improve video from various sources, including the DVD.

In addition, most modern televisions and players offer technologies to adapt DVD video to the latest standards with considerable improvement in detail and accuracy, such as "UHD Upscaling" Developed by Samsung, the "XR" from Sony, the use of artificial intelligence and digital interpolation, indirectly extending the life of the format.

Initially, consumers were also slow to adopt Blu-ray due to cost. As of 2009, 85% of stores sold Blu-ray discs. An HDTV and appropriate connection cables are also required to take advantage of the Blu-ray disc, factors that made the transition difficult. Some analysts suggest that the biggest obstacle to replacing DVD is due to its installed base; a large majority of consumers are satisfied with DVDs. DVD was successful because it offered an attractive alternative to VHS. In addition, the uniform size of the media allows manufacturers to make Blu-ray players (and HD DVD players) backward compatible so that they can play older DVDs as well as MP3 and CD compact discs. digital audio. This is in contrast to the move from vinyl to CD and from tape to DVD, which involved a complete change in the physical medium. As of 2019, it is still common for studios to issue major releases in a 'combo pack' format, which includes both a DVD and Blu-ray Disc (as well as a digital copy). Also, some multi-disc sets use Blu-ray for the primary feature, but DVD for supplementary features (examples of this include the Harry Potter "Ultimate Edition" collections, the 2009 re-release of the 1967 TV series The Prisoner and a 2007 related Blade Runner Collection). Another reason cited (July 2011) for the slower transition to Blu-ray from DVD was the need for and confusion about "firmware updates" and the need for an Internet connection to perform the updates.

This situation is similar to the switch from 78rpm shellac recordings to 45rpm and 33⅓rpm vinyl recordings. Because new and old media shared the same foundation (a record on a record player, played by a needle), phonograph player manufacturers continued to include the ability to play 78rpm for decades after the format was discontinued.

Manufacturers continue to release standard DVD titles as of 2020, and the format remains the preferred format for the release of older movies and TV shows. Programs that were shot and edited entirely on film, such as Star Trek: The Original Series, cannot be released in high definition without rescanning the original film footage. Certain special effects have also been updated to appear better in high definition. Shows made between the early 1980s and early 2000s were generally shot on film, then transferred to cassette tape, and then natively edited in NTSC or PAL, making broadcasts impossible. high definition transfers as these SD standards were included in the final versions. Star Trek: The Next Generation is the only show of its kind to have obtained a Blu-ray release. The process of making high-definition versions of TNG episodes required finding the original film clips, re-scanning them into a computer in high-definition, digitally re-editing the episodes from scratch, and re-rendering new shots. for visual effects, an extraordinarily labor-intensive test that cost Paramount more than $12 million. The project was a financial failure and resulted in Paramount firmly deciding not to give the same treatment to Deep Space Nine and Voyager. However, What We Left Behind included small amounts of remastered footage from Deep Space Nine.

DVDs also face competition from video-on-demand services. With an increasing number of homes having high-speed Internet connections, many people now have the option of renting or buying videos from an online service and watching them by streaming directly from that service's servers, which would mean they no longer need any form of permanent storage. By 2017, digital streaming services had surpassed DVD and Blu-ray sales for the first time. However, due to low cost, the permanence of the physical medium, the accessibility of DVD, and the crisis in video-on-demand services, the format continues in use today.