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DVDDVD 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 but they are encoded in a different format and at a much higher density. The official DVD specification is maintained by the DVD Forum.
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DVD 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 but they are encoded in a different format and at a much higher density. The official DVD specification is maintained by the DVD Forum. HistoryIn 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 format war between VHS and Betamax in the 1980s. Philips and Sony abandoned their MMCD format and agreed upon Toshiba's SD 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. Warner Home Video and Toshiba introduced the new format to Wall Street types, Hollywood big wigs and the investment community at an elaborate staged event on the Warner Bros. lot, hosted by Warner Home Video then President Warren Lieberfarb. The production included the first ever interactive DVD menu designed by producer Billy Pollina. The first DVD players and discs were available in November 1996 in Japan, March 1997 in the United States, 1998 in Europe and in 1999 in Australia. The first pressed DVD release was the film Twister in 1996. The film had the first test for 2.1 surround sound. The first titles released in the U.S., on March 19, 1997, by Lumivision, authored by AIX Entertainment, were IMAX adaptations: Africa: The Serengeti, Antarctica: An Adventure of a Different Nature, Tropical Rainforest, and Animation Greats. By the spring of 1999 the price of a DVD player had dropped below $300 US. At that point Wal-Mart began to offer DVD players for sale, but DVDs represented only a small part of their video inventory; VHS tapes of films made up the remainder. Wal-Mart's competitors followed suit, and DVDs began to increase in popularity with American consumers. DVD rentals first topped those of VHS during the week of June 15, 2003 . Major U.S. retailers Circuit City and Best Buy stopped selling pre-recorded VHS tapes in 2002 and 2003, respectively. In June 2005, Wal-Mart and several other retailers announced plans to phase out the VHS format entirely, in favor of the more popular DVD format. However, blank VHS tapes are still widely available since DVD video recorders are significantly less common than DVD players. Many films released to theaters from 2004 onwards are released solely to DVD format and not to VHS format. Consumers have predicted that 2006 would be the final year for new releases on VHS. While the growth of theatrical films on DVD has cooled recently, that of television programs and music video has increased dramatically. The price of a DVD player has dropped to below the level of a typical VCR ; a low-end player with reasonable quality can be purchased for under $35 US in many retail stores and many modern computers are sold with DVD-ROM drives. Also popular are units that have integrated a DVD and VHS VCR into a single device; these can be purchased for under $100 US. Most, but not all, movie "sets" or series have been released in boxed sets, as have some entire seasons or selected episode volumes of older and newer television programs. Format in video game consolesThe Dreamcast, the first of the then "next generation" 128-bit video games consoles, was released by Sega in Japan in 1998, and in the US and Europe in 1999. This did not play DVDs, which were still quite new and expensive and relatively unpopular at the time. Instead, it used a proprietary 1 Gb 4.75 inch disc known as a GD-ROM disc. By 2000, DVD was getting more popular and a redesign was mooted to add in DVD capabilities. Instead, a free DVD player was offered with the machine in some regions, including Europe and Japan. In 2000, Sony released its PlayStation 2 console in Japan. In addition to playing Video Games developed for the system, it was also able to play DVD movies. This proved to be a huge selling point because the PS2 cost less than most DVD players but could of course play video games too. As a result, many electronic stores that normally did not carry video game consoles carried PS2s. Despite many reports of poor and bad playback and green screens, this proved popular and was often used as a primary DVD player until the prices of good standalone players went down. In keeping with this approach, Sony will incorporate Sony's competing successor to DVD, Blu-ray, into its next console, the PlayStation 3. Problems with implementing this and its Digital Rights Management are the official reason for the delay in launching the system. Microsoft's Xbox, released on March 13, 2002 in Europe and in 2001 in the US, had the capability to play DVD discs with an add-on remote control kit, cementing DVD's place in video game consoles. Nintendo's GameCube, released on May 3, 2002 in Europe and on November 18, 2001 in the US, cannot play DVDs but uses a proprietary 3-inch optical disc for its game media. However, a version of the GameCube known as the Panasonic Q plays DVDs. With the Xbox 360, the successor to the Xbox, which was released worldwide in November 2005, DVD playback is built in. A HD-DVD Drive add-on is to be be released in late 2006 to play HD-DVD movies, this will not be released in Japan or Asia. There will be no games released in this format. DVD playback will be available on the upcoming PlayStation 3 as standard, but Nintendo's Wii console, which will use a proprietary 4.5 inch disc for its game media, has been confirmed to be incompatible with DVDs at launch. The Playstation 3 will launch in Japan and the US in November 2006 and in Europe in March 2007, with the rest of the world to follow. DVD Disc capacity| Physical size | Single layer capacity | Dual/Double layer capacity |
|---|
| 12 cm, single sided | 4.7 GB | 8.5 GB | | 12 cm, double sided | 9.4 GB | 17 GB | | 8 cm, single sided | 1.4 GB | 2.6 GB | | 8 cm, double sided | 2.8 GB | 5.2 GB | |
Note: GB means here giga byte equal 10 9 byte. Windows displays gibibyte equal 2 30
DVD recordable and rewriteable
- Main article: DVD recordable
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 , +R/RW , -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 Sony.
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.
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-Video
DVD-Video discs require a DVD-drive and an MPEG-2 decoder . Commercial DVD movies are encoded using a combination of MPEG-2 compressed video and audio of varying formats . Typical data rates for DVD movies range from 3–10 Mbit/s, and the bit rate is usually adaptive. The typical video resolution for an NTSC disc is 720 × 480, while a PAL disc is 720 × 576. The specifications for video files on a DVD can be any of the following:
- Up to 9.8 Mbit/s MPEG-2 video
- Up to 1.856 Mbit/s MPEG-1 video
- 720 × 576 pixels MPEG-2
- 704 × 576 pixels MPEG-2
- 352 × 576 pixels MPEG-2
- 352 × 288 pixels MPEG-2
- 352 × 288 pixels MPEG-1
- 720 × 480 pixels MPEG-2
- 704 × 480 pixels MPEG-2
- 352 × 480 pixels MPEG-2
- 352 × 240 pixels MPEG-2
- 352 × 240 pixels MPEG-1
All MPEG video must be 25 frames per second on PAL DVDs. On NTSC DVDs MPEG-2 video can be either 29.97 frames per second or 23.976 frames per second, while MPEG-1 video can only be 29.97 frames per second. Interlacing is only supported for MPEG-2 video on both PAL and NTSC DVDs. anamorphic video is only supported at 720x576/480.
Some DVD-hardware or software players may play discs whose MPEG files do not conform to the above standards; commonly this is used to support DVD discs authored with formats such as VCD and SVCD. While VCD and CVD video is supported by the DVD standard, neither SVCD video nor VCD, CVD, or SVCD audio is compatible with the DVD standard. Some hardware players will also play DVD-ROMs or CD-ROMs containing MPEG video files; these are "unauthored" and lack the file and header structure that defines a DVD-video. .
A high number of audio tracks or a large amount of extra material on the disc will often result in a lower bit rate for the main feature. The total bitrate including video, audio and subtitles can be a maximum of 10.08 Mbit/s .
The audio data on a DVD movie can be PCM, DTS, MPEG-1 Audio Layer II , or Dolby Digital format. In countries using the PAL system standard DVD-Video releases must contain at least one audio track using the PCM, MP2, or AC-3 format, and all standard PAL players must support all three of these formats. A similar standard exists in countries using the NTSC system, though with no requirement mandating the use or support for the MP2 format. The vast majority of commercial DVD-Video releases today employ AC-3 audio. The official allowed formats for the audio tracks on a DVD Video are:
- PCM: 48 kHz or 96 kHz sampling rate, 16 bit or 24 bit L-PCM, 2 to 6 channels, up to 6144 kbit/s
- AC-3: 48 kHz sampling rate, 1 to 5.1 channels, up to 448 kbit/s
- DTS: 48 kHz sampling rate, 2 to 6 channels, Half Rate or Full Rate
- MP2: 48 kHz sampling rate, 1 or 2 channels, up to 256 kbit/s
DVDs can contain more than one channel of audio to go together with the video content, supporting a maximum of 8 simultaneous audio tracks per video. This is most commonly used for different audio formats -- 5.1 DTS, 2.0 AC3, etc. -- as well as for commentary and audio tracks in different languages.
With several channels of audio from the DVD, the cabling needed to carry the signal to an amplifier or TV can occasionally be somewhat frustrating. Most systems include an optional digital connector for this task, which is then paired with a similar input on the amplifier. The physical connection is typically RCA connectors or TOSLINK, which transmits a S/PDIF stream carrying either uncompressed digital audio or the original compressed audio data to be decoded by the audio equipment.
Video is another issue which continues to most present problems. Current players typically output analog video only, both composite video on an RCA jack, as well as S-Video in the standard connector. However neither of these connectors were intended to be used for progressive video, so yet another set of connectors has started to appear, to carry a form of component video, which keeps the three components of the video, one luminance signal and two color difference signal, as stored on the DVD itself, on fully separate wires . The connectors are further confused by using a number of different physical connectors on different player models, RCA or BNC, as well as using VGA cables in a non-standard way . Even worse, there are often two sets of component outputs, one carrying interlaced video, and the other progressive. In Europe , SCART connectors are typically used, which can carry composite, Y/C , and/or analog RGB interlaced video signals, as well as analog two-channel sound on a single convenient multiwire cable. The analog RGB component signal offers video quality which is superior to S-Video and identical to YPbPr component video . However, analog RGB and S-Video signals can not be carried simultaneously, due to each using the same pins for different uses, and displays often must be manually configured as to the input signal, since no switching mode exists for S-Video. Some DVD players and set-top boxes offer YPbPr component video signals over the wires in the SCART connector intended for RGB, though this violates the official specification and manual configuration is again necessary. HDMI is a new digital connection similar to DVI; it carries High Definition, Enhanced Definition and Standard Definition video. Along with video HDMI also supports up to eight-channel digital audio. Some HDMI-equipped DVD players can upconvert the video to higher definition formats such as 720p and, more rarely, 1080p.
DVD Video may also include up to 32 subtitle or subpicture tracks in various languages, including those made especially for the deaf and hearing impaired. They are stored as bitmap images with transparent background and are shown over the video during playback. The subtitle track is contained within the VOB file of the DVD. Subtitles are restricted to four colors and thus tend to look cruder than permanent subtitles on film.
DVD Video may contain Chapters for easy navigation . If space permits, it is also possible to include several versions of certain scenes, though today this feature is mostly used—if at all—not to show different angles of the action, but as part of internationalization to e.g. show different language versions of images containing written text, if subtitles will not do . Multiple angles have found a niche in markets such as yoga and pornography.
A major selling point of DVD Video is that its storage capacity allows for a wide variety of extra features in addition to the feature film itself. This can include audio commentary that is timed to the film sequence, documentary features, unused footage, trivia text commentary, simple games and film shorts.
Other extras that can be included on DVDs are motion menus, still pictures, up to 32 selectable subtitles, seamless branching for multiple storylines, 9 camera angles. And also additional DVD-ROM / data files that only can be read by computer DVD drives.
RestrictionsDVD-Video has four complementary systems designed to restrict the DVD user in various ways: Macrovision, Content Scramble System , region codes, and disabled user operations .
Content-scrambling systemMany DVD-Video titles use content-scrambling system encryption, which is intended to discourage people from copying the disc. Usually, users need to install software provided on the DVD or downloaded from the Internet such as WinDVD, PowerDVD, MPlayer, or VLC to be able to view the disc in a computer system.
Without descrambling first, any digital copy of the disc will be ruined and unplayable everywhere, including computers.
The CSS has caused major problems for the inclusion of DVD players in any open source operating systems, since open source player implementations are not officially given access to the decryption keys or license the patents involved in the CSS. Proprietary software players were also difficult to find on some platforms. However, a successful effort has been made to write a decoder by reverse engineering, resulting in DeCSS. This has led to long-running legal battles and the arrest of some of those involved in creating or distributing the DeCSS code, through the use of the controversial U.S. Digital Millennium Copyright Act, on the grounds that such software could also be used to facilitate unauthorized copying of the data on the discs.
These laws currently affect only the United States; most other countries can use de-scrambling software to bypass the DVD restrictions. A number of software programs have since appeared on the Web to view DVDs on a number of different platforms.
Other measures such as RipGuard, as well as US and international copyright law, may be used to prevent making unauthorized copies of DVDs. CSS decrypting software allows a disc to be copied to hard disk unscrambled and region-specific DVD to be copied as an all-region DVD. It also removes Macrovision, CSS, region codes, and disabled user operations .
Disabled User OperationsDVD-Video allows the disc to specify whether or not the user may perform any operation, such as selecting a menu, skipping chapters, forwarding or rewinding—essentially any function on the remote control. This is known as User Operation Prohibitions, or Prohibited User Operations . Most DVD players respect these commands , although some can be configured to ignore them, particularly open source player software.
Many grey market players ignore UOPs. Many popular DVD "reauthoring" software packages allow the user to strip out UOPs, and burn a new copy without the restrictions. While this may be illegal in some countries, it is commonly argued in online forums that, having legally purchased the DVD and its content, users are ethically entitled to view 'their' content the way they prefer. Many feel that being 'forced' to watch PUO-protected content, and having functions on their playback equipment disabled, is an unfair imposition by the distributor, particularly due to the fact that PUO-protected content is almost inevitably commercial content , meaning that they are forced to view commercials on what they have purchased. Furthermore, ironically a greater percentage of those who do not pirate DVDs are likely to see the UOP controlled anti-piracy warnings than those who do, as the aforementioned ability of authoring software to strip such restrictions ensures that pirated DVDs need not place restrictions on, or even display such messages.
Region codes
Each DVD-Video disc contains one or more region codes, denoting the area[s] of the world in which distribution and playback are intended. The commercial DVD player specification dictates that a player must only play discs that contain its region code. In theory, this allows the motion picture studios to control the various aspects of a release on a region-by-region basis, or ensure the success of "staggered" or late theatrical releases from country to country. For example, the movie 28 Days Later was released on DVD in Europe several months prior to the film's theatrical release North America. Regional coding kept the European DVD unplayable for most North American consumers, thereby ensuring that ticket sales would be relatively unaffected by the late theatrical release.
In practice, many DVD players allow playback of any disc, or can be modified to do so. Entirely independent of encryption, region coding pertains to regional lockout, which originated in the video game industry.
From a worldwide perspective regional coding may be seen as a failure. A huge percentage of players outside of North America can be easily modified to ignore the regional codes on a disc. This, coupled with the fact that almost all televisions in Europe and Australasia are capable of displaying NTSC video, means that consumers in these regions have a huge choice of discs. Contrary to popular belief, this practice is not illegal and in some territories that strongly support free trade it is encouraged.
A normal DVD player can only play region-coded discs designated for the player's own particular region. However, a code-free or region-free DVD player is capable of playing DVD discs from any of the six regions around the world.
Most low-cost DVD players that are sold in supermarkets or other cheap outlets, are not multi-region. Some of the more expensive players e.g. Sony, Loewe etc. are multi-region.
DVD-Audio
DVD-Audio is a format for delivering high-fidelity audio content on a DVD. It offers many channel configuration options 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 or far higher audio quality .
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 developed by the 4C group .
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 . 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 , 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 , Toshiba's HD DVD and Maxell's Holographic Versatile Disc .
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 , 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 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 summer, 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 , 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; see gramophone record for details of that situation. It is also, of course, similar to the VHS/Betamax war in consumer video recorders in the late 1970s.
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 , 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 . The price per gigabyte of a hard disk drive, $0.40 , is growing closer to that of a DVD-ROM, $0.06 ; BD-ROM, $0.03 ; recordable DVD-5, $0.10 ; or recordable DVD-9, $0.30 ; and is lower than the cost of a BD-RE25, $1.20 . Direct access to large amounts of information is much more convenient with a hard disk drive. As broadband becomes fast enough 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 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 , and it is therefore possible that consumers may ignore them.
Direct-to-DVD The popularity of DVDs has caused the term "direct-to-DVD" to widely replace "Direct-to-video" . However, the lucrative market for DVDs has resulted in less stigma for direct-to-DVD releases as compared to direct-to-video releases. Some minor films can be made with a small budget and turn a profit on DVD sales alone, and some are made specifically for this purpose.
See also
References
- Bennett, Hugh. Understanding Recordable & Rewritable DVD. OSTA Home Page. April 2004. Optical Storage Technology Association. 30 Apr. 2004.
- Labarge, Ralph. DVD Authoring and Production. Gilroy, Calif.: CMP Books, 2001. ISBN 1-57820-082-2.
- Taylor, Jim. DVD Demystified, 2nd edition. New York: McGraw-Hill Professional, 2000. ISBN 0-07-135026-8.
External links
Official
Forum- - discussion forum for VCD, SVCD and DVD Capturing, Encoding, Authoring and Playing
- - one of the global communities about CDs and DVDs
- - email forum with archive availability all about DVD, contemporary formats and encoding
Quality Guide- Blank DVD media quality guide - How to pick the best DVD discs
- - Informational Guide to the Dual Layer Recording Process
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