User:Megapixie/Laserdisc

The LaserDisc (LD) is a home video disc format, and was the first commercial optical disc storage medium. Initially marketed as Discovision in 1978, the technology was licensed and sold as Reflective Optical Videodisc, Laser Videodisc, Laservision, Disco-Vision, DiscoVision, and MCA DiscoVision until Pioneer Electronics purchased the majority stake in the format and marketed it as LaserDisc in 1983.

While the format itself produced a consistently higher quality image than its rivals, the VHS and Betamax systems, it was poorly received in North America. In Europe and Australia, it also remained largely an obscure format. It was, however, much more popular in Japan and in the more affluent regions of South East Asia, such as Hong Kong and Singapore. Laserdisc was the prevalent rental video medium in Hong Kong during the 1990s.

The technology and concepts provided with the Laserdisc would become the forerunner to Compact Discs and DVDs.

Early Videodiscs
There were a number of disc systems that pre-date laserdisc begining in 1898 when E & H T Anthony, a camera maker based in New York marketed a combination motion picture camera and project called "The Spiral" that could capture 200 images arranged in a spiral on an 8 inch diameter glass plate, which when played back at 16 frames per second would give a running time of 13 seconds.

Theodore Brown patented in 1907 (patent GB190714493) a photographic disk system of recording a approximately 1,200 images in a spiral of pictures on 10 inch disk. Played back at 16 frames per second, the disk could around one and a quarter minutes of material. The system was marketed as the Urban Spirograph by Charles Urban, and discs were produced - but it soon disappeared

John Logie Baird, created the Phonovision system in the early 1930s, which mechanically produced about four frames per second. The system was not successful.

P.M.G Toulon, a French inventor working at Westinghouse Electric during the 1950s and 1960s patented a system in 1952 (Patent 3198880) which used a slow spinning disc with a spiral track of photographically 1.5 millimeter wide recorded frames, along with a flying spot scanner, which swept over them to produce a video image. This was intended to be synronously combined with playback from a vinyl record. It appears a working system was never produced. It had similarities with the tape based Electronic Video Recording system, which was released for professional use.

Gregg at Westrex
David Paul Gregg, an American engineer who had worked at Ampex was working at Westrex where Stereo record were being invented when it occured to him that it might be possible to record Ampex pulse modulated video onto a disc that could be manufactured through hydraulic pressing and therefore mass produced. He read an article in SPIE about two German physists working at the University of Tubingen who had recorded broken parallel lines around 20 nanometers wide using an electron beam microscope. He imagined recording a spiral track with a 40 nanometer pitch, using the breaks in the lines as pulses in pulse encoded video. Westrex wasn't interested in developing the technology, and in the end Gregg moved on to 3M.

3M
Gregg joined the newly aquired Mincom divsion at 3M in 1960 and proposed the Videodisc system, provided them with an explaination of his electron beam based mastering. 3M were interested and developed the project into a series of patents, which named Gregg. , and a prototype player. However, when Gregg asked 3M to recognize his rights as the inventor of the system they demured, and Gregg ended up leaving 3M after only three months, subsequently founding Gauss Electrophysics.

3M continued working for some time on the Videodisc concept, including a photographically recorded design created by Philip Rice that began development in 1964.

Gauss Electrophysics
Gauss Electrophysics which was founded by David Paul Gregg and Keith Johnson was a small electronics company, that had some success with high speed magnetic audio tape duplication, and had been trying to find a larger partner to join forces with to develop and produce the Videodisc system Gregg had devised. They pitched the idea to a several companies during the mid 1960s, and made a complete technical disclosure to Philips, who did not express interest at the time.

In 1967 Gauss's videodisc project came to MCA's attention. At the time MCA had a 11,000 title catalogue of movies that were earning very little revenue, the idea of being able to sell copies of the films direct to consumers was appealing, and in early 1968, MCA made a $300,000 investment, securing a 60% controlling interest in Gauss.

MCA DiscoVision
MCA immediately went to work and hired a consultant, Kent D. Broadbent, to independantly evaluate the Videodisc system. Broadbent was enthusiastic about the projects prospects and estimated that for a cost of producing a motion picture MCA could have a home video format to release their catalogue onto. Broadbent was made head of the project, and immediately assembled a team of engineers to begin work commercialising it. One key early decision was to use a Helium-Cadmium laser for mastering and a Helium-Neon laser for playback.

MCA spun off MCA Laboratories to focus on the development of the format. By 1971 enough progress had been made to demonstrate to MCA executives playback from glass master discs, replication was still being worked out, but it was felt that the most difficult problems had been solved.

On 12 December 1972, the first press demonstration was conducted. An FSX-101 prototype player played seven minutes of footage from a replicated Videodisc for the asembled audience. Reaction was very positive. In the audience were representatives from electronics companies, invited to consider licensing the technology to produce players of their own. This included a representative from Philips, who were at the time were conducting private demonstrations of their own similar videodisc system, which at that stage could only playback from a glass master. Time to market was a key factor, as both MCA and Philips were aware that RCA was working on their own SelectaVision videodisc system which would compete directly with both of them. Philips proposed that rather than compete they should join forces.

Philips "Period of Cooperation"
In 1974 the companies entered into what was described as a "Period of Cooperation". MCA would focus on producing software, Philips would focus on the consumer playback hardware. The relationship was strained, and when the US Justice Department levelled anti-trust charges at the two companies it was left to Philips to deal with the problem. Ultimately the case against the two went nowhere.

When Philips declined to pursue industrial applications for the Videodisc, MCA reached out to the Japanese company Pioneer, who began developing an industrial player, the PR-7820. The original understanding was that Pioneer would only produce playback hardware, but Pioneer could see the possibilities of marketing Japanese software, and to do that they would need domestic disc production facilities. Pioneer eventually pursuaded MCA to allow it to produce software, and the stage was set for Pioneer's later takeover of the format.

Philips purchased the company Magnavox to give it the capability to produce players, and MCA hurriedly setup a disc pressing plant in Carson, in a building previously used as a furniture factory. The Carson plant was to prove extremely problematic, as unlike the production of Vinyl records, the production of optical discs required a clean-room environment, and despite repeated efforts to reduce dust levels, all stages of disc production was affected by particulate contamination.

Test pressing were made to help evaluate the format - these test pressing included:
 * Airport
 * The Andromeda Strain
 * The Day of the Jackal
 * High Plains Drifter
 * Kojak: The Marcus-Nelson Murders
 * The Railway Children
 * The Sting
 * Sweet Charity
 * Jacques Cousteau: Coral Divers of Corsica
 * Jesus Christ Superstar
 * Julia Child: Boeuf Bourguignon

The yield of these pressing was extremely low, reportedly as low as 5%. These early discs were all CAV and single sided, running approximately 25 minutes per side and were somewhat flexible, which caused tracking issues on playback. The decision was made to glue two discs together to give the disc additional stiffness to solve the tracking issues and further protect the sensitive reflective layer.

Competition
The Television Electronic Disc, a mechanical system was rolled out in German and Austria in 1970 by Telefunken. 12 inch discs had a capacity of about eight minutes however it was abandoned in favor of VHS by its parent company.

RCA's CED

JVC's VHD

US Launch
On 13 December 1978, over 10 years after MCAs purchase of Gauss - the MCA and Magnavox held a joint press conference in the Regency Hotel in New York City to announce the launch of the format. The launch was two years after the debut of the VHS video cassette recorder.

Two days later, DiscoVision discs and a $750 VH-8000 Magnavox player went on sale at three Atlanta stores. With only 25 players available, all three stores had sold-out within hours.

Despite promising a catalogue of hundreds of titles upon release, only fifty titles were available on the release day.

Unfortunately problems plagued both the players and the discs, with both Philips and MCA blaming each other for the problems. Philips applied a number of fixes to their player. Pioneer's industrial player - the PR-7820 on the other hand had far fewer problems playing the discs.

The Magnavox player remained the only consumer player on the market until June 1980, when Pioneer started marketing their VP-1000 player, which benefited from their experience developing the PR-7820.

Japanese Launch
Pioneer launched Laserdisc in Japan on October 9 1981, with the Pioneer LD-1000 player costing 228,000 yen ($975) and software ranging from 3,800 yen to 9,800 yen ($16.25 to $41.90).

Pioneer's Kofu plant at that point was pressing was pressing between 2 and 3 million discs a year.

Industrial and Educational Applications
One of the key developments for Discovision, was the sale of 12,000 Laserdisc players to General Motors for use in showrooms, for training, and customer presentations.

In 1979, the Museum of Science and Industry in Chicago opened their "Newspaper" exhibit which used interactive Laserdiscs to allow visitors to search for the front page of any Chicago Tribune newspaper. This was a very early example of public access to electronically stored information in a museum.

It was, however, chosen by the British Broadcasting Corporation (BBC) for the BBC Domesday Project in the mid-1980s, a school-based project to commemorate 900 years since the original Domesday Book in England. Talk about GM

LD players are also sometimes found in contemporary North American high school and college physics classrooms, in order to play a disc of the Physics: Cinema Classics series of mid-20th century Encyclopædia Britannica films reproducing classic experiments in the field which are difficult or impossible to replicate in the laboratories in educational settings. These films have now been released on DVD.

IBM Enters The Picture and The End of Discovision
With various US government departments expressing interest in being able use the 54,000 frame capacity of the Discovision discs. MCA was aware that as an entertainment company, they did not have the depth of technical knowledge to sell the government a complete solution - they entered into talks with IBM regarding a partnership. IBM's own optical storage project called Castle which had been running for several years and had not produced any marketable results.

After months of secret talks, the two companies formed a joint venture called DiscoVision Associates, which IBM bought into for 50 million dollars.

MCA were hopeful that IBMs product development experience would help them work through the replication issues they were having. However, they were unable to reduce the defect rate and by 1981, DiscoVision Associates were forced to go back to IBM and MCA for more money, which was not forthcoming.

The Carson plant was sold to Pioneer, who at that point had a clean-room pressing plant running in Kofu, Japan, and were seeing steady growth in the domestic Japanese market for Laserdiscs. This effectively ended the Discovision brand, although the patents held by Discovision Associates still generated licensing revenues.

Pioneer and Philips
In Early 1982 Pioneer estimated that to date 75,000 Laserdisc players had been sold globally, along with around 2 million discs. Despite the exit of MCA, Pioneer and Philips continued to invest in the format. And through the 1980s and 1990s a number of innovations, including digital stereo audio and later 5.1 audio as well as playback enhancements.

CD Video
Philips launched a modified version of the format on 18 March 1987 which they called CD Video, partnering with Sony, Panasonic and Yamaha. Able to hold digital audio, as well as digital audio and analogue video.

Pioneer Takes Control
In late 1989, Pioneer paid $200 million to buy Discovision Associates from IBM and MCA, the significance of this move was to tranfer patent licensing revenues to Pioneer. This proved to be a signficant move as a patent (4,893,297), originally filed in 1968 with extremely broad claims related to optical discs, which was thought either lost or rejected by the patent office was rediscovered. The result of this was that DiscoVision associates now had a very broad patent covering optical disc technology, including DVD and later Blu-ray.

Competition with DVD and Demise
By 1997 there were between two and three million Laserdisc players in US homes, and with a catalogue of around 8,300 in-print titles available. Work done by Dolby, Pioneer and Philips to extends the format with both stereo and 5.1 digital audio, and the addition of digital frame stores to high-end players had greatly increased its attractiveness to consumers.

With the launch of DVD in early 1997, that position was threatened. DVD had several key advantages over Laserdisc: the discs was far smaller, did not require a side change, and most importantly, it was cheaper to produce. This allowed DVD discs to be sold at a lower price point, under cutting Laserdisc. Early DVDs had some quality issues - primarily related to the immaturity of MPEG-2 video compression algorithms and the shortage of manufacturing plants that could produce high-capacity dual-layer discs.

Initial sales of DVD players were slow, and combined with a reluctance on the part of many film studios to fully embrace the format, it appeared that Laserdisc might continue on for some time. During this period Pioneer released combination players that could play both Laserdiscs and DVDs. However DVD player sales rocketed late in 1998, and by mid 1999, the number of DVD players in US homes had overtaken the number of Laserdisc players. From there it was just a matter of time before studios withdrew support from Laserdisc.

The last two titles released in North America were Paramount's Sleepy Hollow and Bringing Out the Dead in 2000. The last Japanese film release was the Hong Kong film Tokyo Raiders from Golden Harvest around the end of 2001.

Production of Laserdisc players in Japan continued until 14 January 2009, when Pioneer ceased production.

Evaluating Laserdisc's Impact
Laserdisc has been completely replaced by DVD in the North American retail marketplace, as neither players nor software are now produced there. Players were still exported to North America from Japan until the end of 2001. The format retained some popularity among American collectors, and to a greater degree in Japan, where the format was better supported and more prevalent during its life. In Europe, the Laserdisc always remained an obscure format.

It was estimated that in 1998, Laserdisc players were in approximately 2% of US households (roughly two million). By comparison, in 1999, players were in 10% of Japanese households. Laserdisc was released on June 10, 1981 and a total of 3.6 million Laserdisc players were sold in Japan. A total of 16.8 million Laserdisc players were sold worldwide of which 9.5 million of them were sold by Pioneer.

The format was more popular in Japan than in North America because prices were kept low to ensure adoption, resulting in minimal price differences between VHS tapes and the higher quality Laserdiscs, helping ensure that it quickly became the dominant consumer video format in Japan. Laserdiscs were also popular alternatives to videocasettes among movie enthusiasts in the more affluent regions of South East Asia, such as Singapore, due to their high integration with the Japanese export market and the disc-based media's superior longetivity compared to videocassette, especially in the humid conditions endemic to that area of the world.

The format also became quite popular in Hong Kong during the 1990s before the introduction of VCDs and DVD; although people rarely bought the discs (because each LD is priced around USD100), high rental activity helped the video rental business in the city grow larger than it had ever been previously. Due to integration with the Japanese export market, NTSC laserdiscs were used in the Hong Kong market, in contrast to the PAL standard used for broadcast (This anomaly also exists for DVD). This created a market for multi-system TVs and multi-system VCRs which could display or play both PAL and NTSC materials in addition to SECAM materials (which were never popular in Hong Kong). Some LD players could convert NTSC signals to PAL so that most TV used in Hong Kong could display the LD materials.

US Market Impact
During 1995, 7.9 million laserdiscs were sold in the US, worth $334 million, by comparison the video tape market was worth between six and eight billion dollars , implying that Laserdiscs made up around 5% of the total home-video market in the US.

The market for individual titles was varied, cumulatively the Star Wars films sold over a million sets including over 70,000 of the $250 Definitive Collectors Edition. Jurassic Park sold over 600,000 copies, and Terminator 2 sold over 300,000 copies. Typical releases of recent successful Hollywood movies in the mid 90s tended to ship between 100,000 and 200,000 units.

By 1998 the number of new Laserdisc players being shipped to retailers had fallen below 50,000 a year from 250,000 in 1995, and major retailers were dropping the format.

Japanese Market Impact
The total Japanese home-video market was worth 260.38 billion yen ($2.47 billion) in 1995, with laserdiscs making up 61.73 billion yen ($587 million) or 23 percent of the total.

The "Special Edition"
The format's support for multiple audio tracks, and tens thousands of thousands of still frames allowed for large amounts of supplemental materials to be included with film releases. Released with the 1984 debut of the Criterion Collection were Laserdiscs of Citizen Kane and King Kong that are generally credited as being the first "Special Edition" releases to home video. Citizen Kane included the original theatrical trailer, production stills and written essays. King Kong added a commentary track by film historian Ron Haver as well as a pictorial essay on the film. From 1986 forward all Criterion Collection titles would only be issued in their original aspect ratio.

With the advent of digital audio on NTSC discs it was possible to offer a Stereo soundtrack, in addition to two extra audio tracks, which could include commentary tracks or isolated musical scores. Simple VBI programming codes allowed video supplements on CAV discs to be interleaved with still frame material, and chapter marks allowed random access to materials.

Pioneer's 1993 edition of Terminator 2: Judgement Day offered a large amount of extra material including 15 minutes of extra footage and three whole CAV sides of material devoted to exploring the making of the film. Other notable laserdisc special editions include Brazil which included two cuts of the film and a documentary, the Star Wars The Definitive Collection which included all three movies, and numerous special features.

Laserdisc special edition versions of films commanded premium prices, typically ranging from $50 to $130 and beyond.

Intellectual Property
Several of the scientists responsible for the early research (Richard Wilkinson, Ray Dakin and John Winslow) founded Optical Disc Corporation (now ODC Nimbus).

Branding
During its development, MCA, which co-owned the technology, referred to it as the Optical Videodisc System, "Reflective Optical Videodisc" or "Laser Optical Videodisc", depending on the document; changing the name once in 1969 to Disco-Vision and then again in 1978 to DiscoVision (without the hyphen), which became the official spelling. Technical documents and brochures produced by MCA Disco-Vision during the early and mid-'70s also used the term "Disco-Vision Records" to refer to the pressed discs. MCA owned the rights to the largest catalog of films in the world during this time, and they manufactured and distributed the DiscoVision releases of those films under the "MCA DiscoVision" software and manufacturing label &mdash; consumer sale of those titles beginning on December 15, 1978.

Philips' preferred name for the format was "VLP", after the Dutch words Video Langspeel-Plaat ("Video long-play disc"), which in English-speaking countries stood for Video Long-Play. The first consumer player, the Magnavox VH-8000 even had the VLP logo on the player. For a while in the early and mid-'70s, Philips also discussed a compatible audio-only format they called "ALP", but that was soon dropped as the Compact Disc system became a non-compatible project in the Philips corporation. Until early 1981, the format had no 'official' name; however, the LaserVision Association, made up of MCA, Universal-Pioneer and Philips/Magnavox, was formed to standardize the technical specifications of the format (which had been causing problems for the consumer market) and finally named the system officially as "LaserVision".

In Europe, the format was introduced in 1983 with the LaserVision name although Philips used "VLP" in model designations, such as VLP-600. Philips tried renaming the entire format in 1987 to "CD-Video", and while the name and logo appeared on players and labels for years, the 'official' name of the format remained LaserVision. In the early 1990s, the format's name was finally changed to LaserDisc.

During the early years, MCA also manufactured discs for other companies including Paramount, Disney and Warner Bros. Some of them added their own names to the disc jacket to signify that the movie was not owned by MCA. After Discovision Associates shut down in early 1982, Universal Studio's videodisc software label, called MCA Videodisc until 1984, began reissuing many DiscoVision titles.

Pioneer
Pioneer Electronics also entered the optical disc market in 1977 as a 50/50 joint-venture with MCA called Universal-Pioneer and manufacturing MCA designed industrial players under the MCA DiscoVision name (the PR-7800 and PR-7820). For the 1980 launch of the first Universal-Pioneer player, the VP-1000, the name became Laser Disc (with a 'rainbow' type logo joining the two words) and in 1981 the intercap was eliminated and "LaserDisc" became the final and common nickname for the format, although the official name was LaserVision. However, as Pioneer reminded numerous video magazines and stores in 1984, LaserDisc was a trademarked word, standing only for LaserVision products manufactured for sale by Pioneer Video or Pioneer Electronics. A 1984 Ray Charles ad for the LD-700 player bore the term "Pioneer LaserDisc brand videodisc player." From 1981 until the early '90s, all properly licensed discs carried the LaserVision name and logo, even Pioneer Artists titles.

On single sided Laserdiscs mastered by Pioneer, playing the wrong side will cause a still screen to appear with a happy, upside down turtle that has a Laserdisc for a stomach (nicknamed the "Laserdisc Turtle"). The words "Program material is recorded on the other side of this disc" are below the turtle. Other manufacturers used a regular text message without graphics.

Disc Format
The standard home video laserdisc is 30 cm (11.81 inches) in diameter, and 2.7 mm thick with a 3.5 cm central hole. It is made up of two thin aluminum discs layed in plastic. The aluminium discs have a microscopic pattern of pits pressed into them during manufacter which holds both the video and audio signals. Laserdiscs use a pulse-FM signal encoded onto a track of microscopic pits pressed into the aluminium layer of the disc. The pits vary in length, and spacing, describing the shape of an FM carrier signal with a bandwidth of 9.4 Mhz for an NTSC disc, and 7.9 Mhz for a PAL disc. This carrier signal contains both the video signal and audio signals at different points in its spectrum, allowing them to be demodulated upon playback. Note: Insert CAV vs CLV track layout

The pits are read by a 6328 Angstrom (630 nm) laser that follows the track of pits by tracking the reflected signal using six photo diodes in a feedback circuit, which continuously adjusts both the aim point and focus of the laser using a moveable mirror. The pits themselves are on overage 1.3um apart and are a quarter of the laser's wavelength deep. This depth is important, because it causes the reflected laser light to be partially cancelled by Destructive interference, the varation in the reflected light is captured by the four of the photo diodes, whose output is summed to reconstruct the pulse-FM signal. Once the pulse FM signal is reconstructed the individual video and audio signals can be demodulated and processed.

Note: Insert mirror diagram

Modes of Encoding
Three methods were used to arrange the pits into tracks for the player:

CAV
CAV or Standard Play/Active Play discs supported several unique features such as freeze frame, variable slow motion and reverse. CAV discs were spun at a constant rotational speed (1800 rpm for 525 line and 1500 rpm for 625 line discs) during playback, with one video frame read per revolution. In this mode, 54,000 individual frames or 30 minutes of audio/video could be stored on a single side of an NTSC CAV disc. Another unique attribute to CAV was to reduce the visibility of crosstalk from adjacent tracks, since on CAV discs any crosstalk at a specific point in a frame is simply from the same point in the next or previous frame.

CLV
CLV or Extended Play discs, where the track are arranged in a spiral, with a constant linear length. As the disc is read from inner-most track to outer-most track, the rotation speed reduces from 1500 rpm to around 550 rpm. As a result of this arrangement CLV do not have the "trick play" features of CAV, offering only simple playback on machines without digital frame stores. CLV encoded discs could store one hour minutes content per side, or 2 hours per disc. For films with a run–time less than two hours, this meant they could fit on a single disc.

CAA
In the early 1980s, due to problems with crosstalk distortion on CLV extended play Laserdiscs, Pioneer Video introduced CAA formatting for extended play discs. Constant Angular Acceleration is very similar to Constant Linear Velocity, save for the fact that CAA varies the angular rotation of the disc in controlled steps instead of gradually slowing used in CLV. This has the effect of dividing the disc into a series of zones, each effectively CAV with a whole number of fields per rotation except for transition periods between zones. Because the fields are aligned from track to track visiblity of herringbone distortion is greatly reduced. With the exception of 3M/Imation, all Laserdisc manufacturers had adopted the CAA encoding scheme by the mid 1980s although they continued to describe the discs as CLV.

As Pioneer introduced Digital Audio to Laserdisc in 1985, they further refined the CAA format. CAA55 was introduced in 1985 with a total playback capacity of 55 minutes 5 seconds, and was necessary to resolve technical issues with the inclusion of Digital Audio. Several titles released between 1985 and 1987 were analog audio only due to the length of the title and the desire to keep the film on one disc (e.g., Back to the Future). By 1987, Pioneer had overcome the technical challenges and was able to once again encode in CAA60—allowing a total of 60 minutes, 5 seconds. Pioneer further refined CAA, offering CAA45—encoding 45 minutes of material, but filling the entire playback surface of the side. Used on only a handful of titles, CAA65 offered 65 minutes 5 seconds of playback time. The final variant was CAA70, which could accommodate 70 minutes of playback time. There are not any known uses of this format on the consumer market.

Later the specification was changed to permit players to use 780nm lasers.

Video
PAL and NTSC video signals are filtered during the mastering stage. To compensate for the group delay introduced by the low-pass filter used on playback, the video signal is pre-distored with a frequency variable delay peaking at 200ns, additionally a 6db per octave pre-emphasis is applied to the high frequency components of the video signal.

Audio
Audio could be stored in either analog or digital format and in a variety of surround sound formats. Due to differences in the carrier frequencies used on the discs, there are differences in the number of audio channels the PAL and NTSC disc formats could carry. This was due to the fact that the FM modulated PAL video signal consumed a greater proportion of the available frequency bandwidth on the disc, leaving no room for both analogue and digital sound tracks. As a result PAL discs could carry one pair of audio tracks, either analog or digital.

Later enhancements saw the addition of Dolby Digital and DTS sound.

Analogue FM Audio
The two FM audio channels occupied the disc spectrum at 2.3 and 2.8 MHz on NTSC formatted discs, and at 0.683 and 1.066 MHz on PAL discs. Each channel had a 100 kHz FM deviation. NTSC analogue audio has a native signal-to-noise ratio of about 55dB, and PAL around 65dB, both are boost by 15dB with the use of CX noise reduction.

The FM audio carrier frequencies were chosen to minimize their visibility in the video image, so that even with a poorly mastered disc, audio carrier beats in the video will be at least -35db down, and thus, invisible.

Due to the frequencies chosen, the 2.8 MHz audio carrier (Right Channel) and the lower edge of the chroma signal are very close together and if filters are not carefully set during mastering, there can be interference between the two. In addition, high audio levels combined with high chroma levels can cause mutual interference, leading to beats becoming visible in highly saturated areas of the image. The analog soundtracks varied greatly depending on the disc and, sometimes, the player.

CX encoding
To resolve the various issues with the sound quality of the analogue audio tracks, Pioneer decided to implement the CX Noise Reduction System, which was used in the CED video disk format, on the analog tracks. By reducing the dynamic range and peak levels of the audio signals stored on the disc, filtering requirements were relaxed and visible beats greatly reduced or eliminated. The CX system gives a total NR effect of 20db, but in the interest of better compatibility for non-decoded playback, Pioneer reduced this to only 14db of noise reduction. This also relaxed calibration tolerances in players and helped reduce audible pumping if the CX decoder wasn't calibrated correctly.

Stereo Digital Audio
In 1984 Phillips conducted work to add Stereo 16 bit and 44.1 kHz sample rate digital audio to the Laserdisc format. . The addition of digital audio was achieved by adding a new signal to the lowest part of frequency spectrum carried by the laserdisc, and the addition of some filtering of the composite video carrier on mastering to supress generation of the J2 side-band component that would otherwise interfere with the new signal.

Eight-to-Fourteen Modulation was used to encode the signal, with an addition layer of Cross-interleaved Reed-Solomon coding to allow errors to be transparently corrected. The encoded signal was then pre-emphased by 23 dB at 32khz, rolling off to zero at 500khz to compensate for noise generated by the Helium-Neon laser.

This scheme allowed NTSC discs to retain both analogue audio tracks, however due to the larger frequency range required by the PAL composite signal, and the lower disc rotation rate, there was not room to retain analogue audio on PAL discs.

Dolby Digital
Pioneer working with Dolby Labs presented a demonstration of a laserdisc player playing a prototype copy of "The Fugative" with a Dolby Digital soundtrack (also refered to as AC-3) at the Consumer Electronics Show in Las Vegas in January 1994. Pioneer's 1995 lineup of laserdisc players all included AC-3 modulated signal output, and on 31 January 1995 the first Dolby Digital laserdisc, Clear and Present Danger, was released. The Runco LJRII player, released in 1994, was the first player to feature an output for the modulated AC-3 signal, although kits and services retrofitting the feature to older players were common.

Adding Dolby Digital to Laserdisc was achieved by replacing the right analogue audio track with a 500 kilobit a second Quadrature Phase Shift Keying signal with a bandwidth of around 250khz. The QPSK signal wrapped a 384 kilobit-per-second Dolby Digital bitstream that could be decoded into 5.1 channel surround sound by a decoder. Typically this was acheived by providing an 'AC-3 RF-out' on the Laserdisc player, which conveyed the bandpassed QPSK modulated stream. This was then through a demondulator circuit, and then sent to a Dolby Digital processor.

On 7 April 2000 Star Wars: Episode I one of the last laserdiscs produced, was released in Japan, including a 6.1 channel Dolby Digital EX Surround. . The Laserdisc database lists a total of 1,124 laserdiscs with Dolby Digital sound released globally.

DTS
DTS audio, when available on a disc, replaced the digital audio tracks; hearing DTS sound required a S/PDIF compliant digital connection to a DTS decoder. Jurassic Park, released in January 1997, was the first laserdisc with a DTS sound track. As DTS displaced the stereo audio soundtrack, it never became a common feature PAL discs, which did not have analogue tracks to fall back on, in fact only a single PAL laserdisc was released with a DTS soundtrack - the German film Schlafes Bruder, interestingly this was also one of the few PAL-plus laserdiscs produced.

Although there was no technical reason why AC-3 and DTS could not be placed on the same NTSC laserdisc, this was never done in practice, so if a DTS decoder was also not available, the only option is to fall back to the analog audio tracks. In some cases, the analog audio tracks were further made unavailable through replacement with supplementary audio such as isolated scores or audio commentary. This effectively reduced playback of a DTS disc on a non-DTS equipped system to mono audio—or in a handful of cases, no film soundtrack at all.

DTS on Laserdisc never achieved the market penetration of AC-3, with the Laserdisc Database recording only 158 individual laserdiscs released globally with DTS soundtracks, compared with over 1,000 AC-3 releases globally.

Teletext, Closed Captions TOC, Timecode and Frame Counters
Because Laserdisc video encodes the entire video vertical blanking interval interval, it is possible for Teletext or Closed Caption subtitles to be carried along with the video. In addition, lines 16, 17 and 18 or 279, 280 and 281 contain 24 bit Phillips codes. These are encoded using Manchester encoding, and provide disc, frame number and chapter information to the player. On line 11 or 274 is the white flag which indicates that the field is the first field of a frame.

A second 40 bit FM coded signal is also incorporated into the format, dubbed the MCA code, it is present on line 10 and 273. It is an FM coded data signal containing time information on CLV discs and picture number on CAV discs, as well as lead-in and lead-out flags. This field was only actively used by early industrial players, and is normally ignored by all players manufactured after 1984.

With the addition of digital audio, a second metadata stream in the form of Red Book P and Q subcodes was available. These codes were kept in sync with the Phillips codes at mastering time, and provided track/chapter numbers as well as duration information about the track. This allowed the addition of a "Table of Contents" or TOC in the lead-in area, which was read at the start of playback of a side of a disc and provided the player with the location of chapter start points, as well as a total running time. This allowed the player to display time remaining, as well as to find chapters marks more quickly.

Laser rot
Many early LDs were not manufactured properly; sometimes a substandard adhesive was used to sandwich together the two sides of the disc. The adhesive contained impurities that were able to penetrate the lacquer seal layer and chemically attack the metalized reflective aluminium layer, causing it to oxidize and lose its reflective characteristics. Some forms of laser rot could appear as black spots that looked like mold or burned plastic which would cause the disc to skip and the movie to exhibit excessive speckling noise. But, for the most part, rotten discs may actually appear perfectly fine to the naked eye.

Later optical standards have been known to suffer similar problems.

Playback Hardware
Note: Insert Playback block diagram Note: Insert explaination of block diagram

1978 to 1983
The earliest players employed gas Helium-neon laser tubes to read discs and had a red-orange light with a wavelength of 628 Nanometers, while later solid-state players used infrared semiconductor laser diodes with a wavelength of 780 Nanometers. Many Pioneer Model-III (DiscoVision PR-7820), VP-1000, LD-1100, LD-660 and PR-8210s are still in good working order. Both the Magnavox Magnavision and the Pioneer LD players used the same model of laser tube. Optical hobbyists have been known to cannibalize the laser tube machines. From 1978 until 1984, basically all LaserDisc players, either industrial or consumer, used Helium-Neon laser tubes.

1984 to 1989
In March 1984, Pioneer introduced the first consumer player with a solid-state laser, the LD-700. It was also the first LD player to load from the front and not the top. One year earlier Hitachi introduced an expensive industrial player with a laser diode, but the player, which had poor picture quality due to an inadequate drop-out compensator, was made only in limited quantities. After Pioneer released the LD-700, gas lasers were no longer used in consumer players, despite their advantages, although Philips continued to use gas lasers in their industrial units until 1985. Helium-Neon gas lasers had a shorter-wavelength laser that created a much smaller spot on the disc, leading to better tracking of imperfectly manufactured discs - such as an off-center hole punch or slightly eccentric tracks. The use of a solid state laser diode necessitated the introduction of the tilt-servo mechanism in LD players; this physically tilted the entire laser table, keeping it parallel with the disc, thus ensuring the larger laser beam spot was always perfectly circular and helping to reduce or eliminate crosstalk on warped CLV discs. In addition, the gas laser was less sensitive to external vibration, a must in certain industrial environments, and generated less photon-shot noise than the solid-state laser diode, resulting in a cleaner, less 'busy' on-screen image

The picture produced by the LD-700's laser could be instantly recognized at the time; it was slightly softer, and large expanses of color in the image, such as a blue sky, would show streaking artifacts. Also, the infrared laser did not cope as well with disc manufacturing defects, such as dirt trapped under the surface of the disc (inclusions), an off-center hole or track errors created during mastering, such as track-to-track "kissing" (tracks touching). Because of this, collectors with large MCA DiscoVision collections (DiscoVision discs had just those type of above mentioned defects) tended to use tube-based LaserDisc players since they played these discs better. In addition to being the first LD player to use a laser diode, the Pioneer LD-700 was also the first player ever to have the aforementioned "tilt" servo, which was arguably one of the greatest advances in LD players.

Most machines made were single-sided and required the viewer to manually turn the disc over to play the other side. A number of players (all diode laser based) were made that were capable of playing both sides of the disc automatically; at the end of the first side, or at the viewers command, the machine would reverse the direction of the disc's rotation, simultaneously moving the laser pickup head to the other side of the disc, and then initiate playback. Since LD's are made up of two single sided discs glued together, the auto-reverse player would center each disc side individually, and instead of a simple U-shaped reversing mechanism, Pioneer players physically rotated the laser reading head 180 degrees as it moved from one side of the disc to the other, ensuring that the laser retained the same playback orientation on both sides of the disc. This optimized playback and tracking quality. While Pioneer produced some industrial "jukeboxes" that held more than 50 discs, one company offered, for a short time in 1984, a "LaserStack" unit that required the user to physically remove the player lid for installation and attached to the top of the Pioneer LD-600, LD-1100 or the Sylvania/Magnavox clones. LaserStack held up to 10 discs and could automatically load or remove them from the player or change sides in around 15 seconds. A version for the Magnavox Magnavision and Pioneer VP-1000 was announced, as was a model for the front-loading players, but the company went out of business before the units were available.

Only one consumer player, the LD-W1 (it was also released industrially too), was made that could hold more than a single disc; the W1 held two discs and could automatically change discs and sides by rotating the entire mechanism, including both the laser and turntable. Electrically, the LD-W1 was identical to the Elite LD-S1. The LD-W1 remained in the Pioneer catalog for many years and received many improvements: While the first 'version' of the W1 had only 2X oversampling and 16-bit D/A converters in the digital audio, the later units had 4X oversampling with 20-bit D/A converters. The video noise reduction was improved too, sharpening the picture and reducing disc noise while eliminating the artifacts it caused. In addition, high-frequency response in the FM video demodulator and A/D-D/A converters was extended and flattened, increasing resolution and reducing visible digital artifacts. The W1's player software was refined too, making disc and side-changing faster - plus, during side or disc changes, it grabbed a still-frame closer to the actual end-of-program instead of just any frame from the side's last 5 minutes.

1989 to 2001
Many Laserdisc players manufactured from 1989 to the format's end had both composite (yellow RCA type connectors) and S-Video outputs on the rear panel. When using the S-Video connection, the player would utilize its own internal comb filter, designed to help reduce picture noise by separating the luminance (brightness) and color parts of the signal, while using the composite outputs forced the player to rely on the comb filter of the display device. The claim, made by Philips, was that by using the LD player's internally generated reference for the comb filter's clock, the CCD in the Y/C comb filter delay line could be made much more accurate and 'track' disc rotation changes or errors - this would allow the 'teeth' of the comb to move, if necessary, with changes in the signal and perfectly line up together and with the composite signal, improving luma/chroma separation - the result was less chroma noise and chroma banding plus cleaner, sharper edges in the luminance. The first player released to consumers with a Y/C "S-Video" output was the Philips CDV-488 in spring of 1989. Players with (Y/C) S-Outputs from Pioneer quickly followed. In addition, the Philips CDV-488 was the only player ever sold that had a comb filter made from discrete components and was adjustable (internally) for best performance; For years it was Joe Kane's (of the ISF) reference player, until the Pioneer Elite LD-S2 was introduced. (The LD-S2 was the first player to employ a digital field comb filter and digital video noise reduction.) At the same time (1989) of S-output introduction on LD players, there was industry talk of a "Super", or extended resolution, LD format, much like the "high-band" efforts of JVC and Sony with Super-VHS and ED-Beta. While Pioneer did indeed design such a system (called LD-XR), it was never introduced to the consumer or industrial markets. The S-output on LD players was always controversial. Because the video on an LD is stored as a full-bandwidth NTSC signal, there is no inherent advantage to offering a comb filter with an "S" output on the player - the signal has to be split at some point, either in the player or your monitor, so the only question was, which has the better comb filter, the LD player or the monitor? Until the mid-1990s virtually no consumer monitors and no LD players offered anything other than single-line analog, CCD-based, comb filters. Thus dot-crawl in the image was always present - in fact, lack of dot-crawl (cross-luminance) in the image indicated undesirable, resolution-robbing, filtering somewhere in the signal chain - in other words, a defect. Later LD players offered digital 2- and 3-line comb filters and a few even offered adjustable digital 3D comb filters, but televisions kept pace, making the monitor the overwhelming choice for decoding the LD signal. Many stand-alone (set top) DVD recorders incorporate advanced digital 3D comb filters as well as high quality chroma and luma noise reduction, and using them to split the signal from the LD player is a great way to get improved LD playback, especially if your monitor doesn't have state-of-the-art NTSC decoding - and many modern flat-panel and projection sets do not.

In addition, most DVD recorders have full I/Q chroma bandwidth decoding which many monitors, even high-end, lack. This will provide the full 120-lines of color resolution available from the LD as opposed to the 40-line color available from the standard 'equiband' NTSC decoder in most monitors. In any case, using the composite output with a modern monitor or DVD recorder is the preferred connection. Unfortunately, many players split the signal into luma and chroma before processing it with noise reduction, then recombined it for the composite output. In addition to displaying any errors of the comb filter in the composite output, this could lead to chroma/luma delay errors when using the composite output - in other words, the chroma will be displaced relative to the luma, causing the color to "bleed" outside its intended boundaries. On such players the solution is to use the "S" (Y/C) output and make do with the built-in comb filter.

Combi-players
Most players made after the mid-1980s were capable of also playing audio CDs. These players included a 12 cm indentation in the loading tray, where the CD would be placed for play. At least one Pioneer model (CLD-M301) also operated as a CD-changer, with several 12 cm indentations around the circumference of the main tray.

In 1996, the first model DVD/LD combi-player (and first Pioneer DVD player, for that matter) was the Pioneer DVL-9 released in Japan. The Pioneer Elite DVL-90, an updated version, followed by a similar, though supposedly lower-end model, the DVL-700, were released in 1997. Successors to this model include the Pioneer DVL-909, Pioneer DVL-919, and the Pioneer Elite DVL-91. Although the DVD/LD combi players offered competent LD performance, they paled in comparison to high end LD players such as the Pioneer Elite CLD-99 and the Pioneer Hi-Vision/MUSE HLD-X9.

The Pioneer DVL-909 lacks support for DTS output. However, a modification to the player can allow this player to support DTS streams on DTS discs, essentially turning the DVL-909 into a Pioneer Elite DVL-91.

The last model DVD/LD player was the Japanese only DVL-H9, but the older DVL-919 is still sold in the U.S. and appears on Pioneer's North American website. However, it has not been actively marketed since the late 1990s. The DVL-919 supports DTS output. The DVL-919's DVD section is unremarkable by modern standards, and does not support progressive scan (480p) even though it has component output. As noted above, the LD section, while competent, is inferior to earlier high end LD players. A few Pioneer dealers offer North American specification DVL-919s, and a unit purchased in April 2004 had a manufacture date of December 2003. Manufacturing of the DVL-919 continued until January 1, 2009 when Pioneer announced that production would cease after a final production run of 3000 DVL-919 and other model laser disc players.

High-end Japanese players
Certain Japanese players, which are considered to be of higher quality or of greater capacity for quality playback than the North American units, are occasionally imported by enthusiasts. These include the CLD-R7G, LD-S9, HLD-X9 and HLD-X0. All four are manufactured by Pioneer and three contain technology that was never officially available in North American Laserdisc players.

The CLD-R7G, LD-S9 and HLD-X9 share a highly advanced comb filter, allowing them to offer a considerable advantage in picture quality over most other LD players when the S-Video connection is used. The comb filter present in these players is unique and is purportedly the finest comb filter ever used in consumer A/V gear: it is still currently in use in Mitsubishi's top-spec CRT rear-projection television sets (the Diamond and now defunct Platinum series sets) and Pioneer's Elite line of rear-projection televisions.

In addition to the advanced comb filter, the HLD-X9 contains a red-laser pickup, which significantly reduces crosstalk and picture-noise levels compared to players with the traditional infrared laser; it can also read through all but the worst cases of laser rot and surface wear. The HLD-X9 is, lastly, also a MUSE player, capable when properly equipped of playing back high definition Laserdiscs, called Hi-Vision or MUSE discs in Japan.

The HLD-X0 is Pioneer's original MUSE player, and is the player of choice for many enthusiasts despite the fact that it lacks the comb filter shared by the R7G, S9 and X9. It was entirely hand built from hand picked electronics and weighed 36 kilograms. Many argue that the newer X9 was a more capable MUSE player but that the X0 had superior performance with standard NTSC discs. Nonetheless, the X9 remains the more popular of the two models, as it includes the newer comb filter and is a dual-side player, meaning that double sided discs don't need to be manually flipped over in order for both sides to be played.

on all but the high-end Laserdisc players incorporating a digital frame store

The vast majority of titles were only available in CLV. (A few titles were released partly CLV, partly CAV. For example, a 140-minute movie could fit on two CLV sides and one CAV side, thus allowing for the CAV-only features during the climax of the film.)

The first Laserdiscs featured in 1978 were entirely analog but the format evolved to incorporate digital stereo sound in CD format (sometimes with a TOSlink or coax output to feed an external DAC), and later multi-channel formats such as Dolby Digital and DTS.

S

Other significant players
 Japanese Players


 * Pioneer LD-1000 - Pioneer's first Japanese-market LD player introduced in 1981.
 * Pioneer HLD-X0
 * Pioneer HLD-X9
 * Pioneer LD-S1  - Released in 1986.
 * Pioneer LD-X1  - Known as the Pioneer LD-S2 in America.

American Players


 * Pioneer VP-1000 - Pioneer's first consumer player released in America in 1980.
 * Pioneer LD-1100 - Pioneer's first player to have built-in CX Noise Reduction. Introduced in late 1981.
 * Pioneer LD-1000 - Pioneer's first Japanese-market LD player introduced in 1981.
 * Pioneer CLD-1010 - First player capable of playing 5 in CD-Video discs. Released in 1987.
 * Pioneer LD-S2   - Also known as the Pioneer LD-X1 in Japan.
 * Pioneer CLD-D703
 * Pioneer CLD-97
 * Pioneer CLD-99

''' European Players '''
 * Pioneer CLD-1050 - PAL only
 * Pioneer CLD-2950 - PAL/NTSC Compatible.
 * Pioneer CLD-D925 - PAL/NTSC Compatible.
 * Pioneer DVL-9/DVL-700/DVL-90/DVL-91/DVL-909/DVL-919 - Capable of playing both Laserdiscs and DVD.

Computer control
In the early 1980s Philips produced a Laserdisc player model adapted for a computer interface, dubbed "professional". In 1985, Jasmine Multimedia created laserdisc Juke Boxes featuring music videos from Michael Jackson, Duran Duran, and Cyndi Lauper. When hooked to a PC this combination could be used to display images or information for educational or archival purposes, for example thousands of scanned medieval manuscripts. This strange device could be considered a very early equivalent of a CD-ROM. In one case such a "Laserdisc-ROM" was still present, although rarely used.

In 1986, a SCSI equipped Laserdisc player attached to a BBC Master computer was used for the BBC Domesday Project. The player was referred as an LV-ROM (LaserVision Read Only Memory) as the discs contained the driving software as well as the video frames. The discs used the CAV format, and encoded data as a binary signal represented by the analog audio recording. These discs could contain in each CAV frame video/audio or video/binary data, but not both. "Data" frames would appear blank when played as video. It was typical for each disc to start with the disc catalogue (a few blank frames) then the video introduction before the rest of the data. Because the format (based on the ADFS hard disc format) used a starting sector for each file, the data layout effectively skipped over any video frames. If all 54,000 frames are used for data storage an LV-ROM disc can contain 324MB of data.

Apple's HyperCard scripting language provided Macintosh computer users with a means to design databases of slides, animation, video and sounds from Laserdiscs and then to create interfaces for users to play specific content from the disc. User-created "stacks" were shared and were especially popular in education where teacher-generated stacks were used to access discs ranging from art collections to basic biological processes. Commercially available stacks were also popular with the Voyager company being possibly the most successful distributor.

Commodore International's 1992 multimedia presentation system for the Amiga, AmigaVision, included device drivers for controlling a number of Laserdisc players through a serial port. Coupled with the Amiga's ability to use a Genlock, this allowed for the Laserdisc video to be overlaid with computer graphics and integrated into presentations and multimedia displays, years before such practice was commonplace.

Pioneer also made computer-controlled units such as the LD-V2000. It had a back-panel RS-232 serial connection through a 5-pin DIN connector, and no front-panel controls except Open/Close. (The disc would be played automatically upon insertion.)

Under contract from the U.S. Military, Matrox produced a combination computer laserdisc player for instructional purposes. The computer was a 286, the laserdisc player only capable of reading the analog audio tracks. Together they weighed 43 pounds and sturdy handles were provided in case 2 people were required to lift the unit. The computer controlled the player via a 25-pin serial port at the back of the player and a ribbon cable connected to a proprietary port on the motherboard. Many of these were sold as surplus by the military during the 90s, often without the controller software. It is nevertheless possible to control the unit by removing the ribbon cable and connecting a serial cable directly from the computer's serial port to the port on the laserdisc player.

Computer games
Several companies saw potential in using laserdisc video games in the 1980s and 1990s. American Laser Games and Cinematronics produced elaborate arcade consoles that used the random-access features to create interactive movies such as Dragon's Lair and Space Ace. Similarly, the Pioneer Laseractive and Halcyon were introduced as home video game consoles that used laserdisc media for its software.

MUSE LD
In 1991, several manufacturers announced specifications for what would become known as MUSE Laserdisc, representing a span of almost 15 years until the feats of this HD analog optical disc system would finally be duplicated digitally by HD DVD and Blu-ray. Encoded using NHK's MUSE "Hi-Vision" analogue TV system, MUSE discs would operate like standard Laserdiscs but would contain high-definition 1125-line (1035 visible lines) video with a 5:3 aspect ratio. The MUSE players were also capable of playing standard NTSC format discs and are superior in performance to non-MUSE players even with these NTSC discs. The MUSE-capable players had several noteworthy advantages over standard Laserdisc players, including a red laser with a much narrower wavelength than the lasers found in standard players. The red laser was capable of reading through disc defects such as scratches and even mild disc-rot that would cause most other players to stop, stutter or drop-out. Crosstalk was not an issue with MUSE discs, and the narrow wavelength of the laser allowed for the virtual elimination of crosstalk with normal discs.

In order to view MUSE encoded discs, it was necessary to have a MUSE decoder in addition to a compatible player. There are televisions with MUSE decoding built-in and set top tuners with decoders that can provide the proper MUSE input. Equipment prices were high, especially for early HDTVs which generally eclipsed US$10,000, and even in Japan the market for MUSE was tiny. Players and discs were never officially sold in North America, although several distributors imported MUSE discs along with other import titles. Terminator 2: Judgment Day, Lawrence of Arabia, A League of Their Own, Bugsy, Close Encounters of the Third Kind, Bram Stoker's Dracula and Chaplin were among the theatrical releases available on MUSE LDs. Several documentaries, including one about Formula One at Japan's Suzuka Circuit were also released.

Laserdisc sizes
The most common size of Laserdisc was 30 cm. These approximated the size of LP vinyl records. These discs allowed for 30 minutes per side (CAV) or 60 minutes per side (CLV). The vast majority of programming for the Laserdisc format was produced on these discs.

20 cm Laserdiscs were also published. These "EP"-sized LDs allowed for 20 minutes per side (CLV). They are much rarer than the full-size LDs, especially in North America. These discs were often used for music video compilations (e.g., Bon Jovi's "Breakout", Bananarama's "Video Singles" or T'Pau's "View From A Bridge").

There were also 12 cm "single"-style discs produced that were playable on Laserdisc players. These were referred to as CD Video (CD-V) discs, and Video Single Discs (VSD). A CD-V carried up to 5 minutes of analog Laserdisc-type video content (usually a music video), as well as up to 20 minutes of digital audio CD tracks. The original 1989 release of David Bowie's restrospective Sound and Vision CD box set prominently featured a CD-V video of Ashes To Ashes, and standalone promo CD-Vs featured the video, plus 3 audio tracks: John, I'm Only Dancing, Changes and The Supermen.

CD-Vs are not to be confused with Video CDs (which are all-digital and can only be played on VCD players, DVD players, CD-i players, computers, and later-model Laserdisc players (such as the DVL series from Pioneer that can also play DVDs). CD-Vs can only be played back on Laserdisc players with CD-V capability. VSDs were the same as CD-Vs, but without the audio CD tracks. CD-Vs were somewhat popular for a brief time worldwide, but soon faded from view. VSDs were popular only in Japan and other parts of Asia, and were never really introduced to the rest of the world.

Picture discs
Picture discs have artistic etching on one side of the disc to make the disc more visually attractive than the standard shiny silver surface. This etching might look like a movie character, logo, or other promotional material. Sometimes that side of the LD would be made with colored plastic rather than the clear material used for the data side. Picture disc LDs only had video material on one side as the "picture" side could not contain any data. Picture discs are rare in North America.

LD-G
Pioneer Electronics, one of the format's largest supporters/investors, was also deeply involved in the karaoke business in Japan, and used Laserdiscs as the storage medium for music and additional content such as graphics. The format was generally called LD-G. While several other karaoke labels manufactured Laserdiscs, there was nothing like the breadth of competition in that industry that exists now, as almost all manufacturers have transitioned to CD+G discs (en route, possibly, to a new DVD-based format).

Squeeze LD
With the release of 16:9 televisions in the mid 1990s, Pioneer and Toshiba decided that it was time to take advantage of this aspect ratio. Squeeze LDs are enhanced 16:9 ratio widescreen Laserdiscs. In the video transfer stage the movie is stored in an anamorphic format. The widescreen movie image was stretched to fill the entire video frame with less or none of the video resolution wasted to create letterbox bars. The advantage was a 33% greater vertical resolution compared to letterboxed widescreen Laserdisc. This same procedure was used for DVD. Unlike all DVD players, very few LD players had the ability to unsqueeze the image for 4:3 sets. If the discs were played on a 4:3 television the image would be distorted. Since very few people owned 16:9 displays, the marketability of these special discs was very limited.

There were no titles available in the US except for promotional purposes. Upon purchase of a Toshiba 16:9 television viewers had the option of selecting a number of Warner Brothers 16:9 films. Titles include Unforgiven, Grumpy Old Men, The Fugitive, and Free Willy. The Japanese lineup of titles was different. A series of releases under the banner "SQUEEZE LD" from Pioneer of mostly Carolco titles included Basic Instinct, Stargate, Terminator 2: Judgment Day, Showgirls, Cutthroat Island, and Cliffhanger. Oddly enough Terminator 2 was released twice in Squeeze LD, the second release being THX certified and a notable improvement over the first.

Recordable formats
Another type of video media, CRVdisc, or "Component Recordable Video Disc" were available for a short time, mostly to professionals. Developed by Sony, CRVdiscs resemble early PC CD-ROM caddies with a disc inside resembling a full sized LD. CRVdiscs were blank, write-once, read-many media that could be recorded once on each side. CRVdiscs were used largely for backup storage in professional/commercial applications.

Another form of recordable Laserdisc that is completely playback-compatible with the Laserdisc format (unlike CRVdisc with its caddy enclosure) is the RLV, or Recordable LaserVision disc. It was developed and first marketed by the Optical Disc Corporation (ODC, now ODC Nimbus) in 1984. RLV discs, like CRVdisc, are also a WORM technology, and function exactly like a CD-R disc. RLV discs look almost exactly like standard Laserdiscs, and can play in any standard Laserdisc player after they've been recorded.

The only cosmetic difference between an RLV disc and a regular factory-pressed Laserdiscs is their reflective purple-violet (or blue with some RLV discs) color resulting from the dye embedded in the reflective layer of the disc to make it recordable, as opposed to the silver mirror appearance of regular LDs. The purplish color of RLVs is very similar to some DVD-R and DVD+R discs. RLVs were popular for making short-run quantities of Laserdiscs for specialized applications such as interactive kiosks and flight simulators.

In spite of nonrecordability being commonly regarded as the primary weakness of the Laserdisc format, these recordable LD systems were never marketed toward the general public, and are so poorly known as to create the misconception that a home recording system for Laserdiscs is impossible.

Resources

 * Jordan Isailovic, Videodisc and Optical Memory Systems Vol. 1, Boston: Prentice Hall, 1984. ISBN 978-0139420535
 * Lenk, John D. Complete Guide to Laser/VideoDisc Player Troubleshooting and Repair. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-160813-4.