Laserdisc

From Academic Kids

Missing image
Logo-LD2.gif
Pioneer's LaserDisc Logo

The Laserdisc (LD) was the first commercial optical disc storage medium, and was used primarily for the presentation of movies.

During its development, the format was referred to as the "Reflective Optical Videodisc System" before MCA, who owned the patent on the technology, re-named the format Disco-Vision in 1969. By the time the format was brought to market in 1978, the hyphen was removed from the format name. They marketed it under the name DiscoVision beginning December 15, 1978 after the earlier CRV disc format had died out in obscurity. MCA owned the rights to the largest catalog of films in the world during this time, and they directly manufactured and distributed the discs of their movies under the "MCA DiscoVision" label. Pioneer Electronics, who entered the market almost at exactly the time DiscoVision titles were going on sale in 1978, began manufacturing players and printing discs under the name laser videodisc. By 1981, Laserdisc (first with intercaps as LaserDisc, then later without) had become the common name for the format, and the Discovision label disappeared, simply becoming MCA or (later) MCA-Universal Laserdisc.

MCA also manufactured discs for other companies, including Paramount, Disney and Warner Brothers. Some of them added their own names onto the disc-jacket in order to signify the movie was not owned by MCA. When MCA folded into Universal several years later, Universal began re-issuing many of the early DiscoVision titles as Universal discs. The DiscoVision versions had largely been available only in pan and scan and had often utilized poor transfers. The Universal versions were largely better. The format has also been known as LV (for "LaserVision", actually a player brand by Philips). The players are also sometimes referred to as VDPs (Video Disc Players).

Contents

History

Laserdisc technology was invented by David Paul Gregg in 1958, patented in 1961 and 1969, and first publicly demonstrated by Philips and MCA in 1972. It was first available on the market on December 15, 1978, two years after the VHS VCR and five years before the CD.

There are more than 1 million players in home use in the US (compared to 85 million VCRs), and more than 4 million in Japan (or 10% of households). LD has been completely replaced by DVD in the North American retail marketplace, as both players and software are no longer produced. Laserdisc has 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.

Technical information

Like on a CD, the surface of a laserdisc is composed of aluminium foil covered by pits and lands, but Laserdisc Video was stored in Analog Format. So whereas on an audio CD (or DVD) the pits and lands will signify binary codes, on an LD the pits are created using frequency modulation of an analog signal. The discs were recorded in one of two formats: CAV (constant angular velocity) or CLV (constant linear velocity). CAV discs were spun at a constant rotational speed during playback, with one video frame read per revolution, whereas CLV discs spun progressively slower as the disc was played from inside edge to outside edge. A CAV disc holds up to 30 minutes of content per side, while a CLV disc can hold twice that.

The main advantage of the CAV format was that its simpler playback method allowed "trick play" features such as freeze frame, slow motion, and reverse on all LD players, while CLV discs required a digital frame buffer to perform the same tasks, which was found only in high-end models. Another advantage was to reduce the visibility of cross talk from adjacent tracks, since on CAV discs this is simply the same point in the next or previous frame. The vast majority of titles were only available in CLV.
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LDDVDComparison.jpg
A physical comparison of a laserdisc with a DVD.

Audio could be stored in either analog or digital format and in a variety of surround sound formats; NTSC discs could carry two analog audio tracks, plus two uncompressed PCM digital audio tracks, which were CD quality and PAL discs could carry one pair, either analog or digital. Dolby Digital (also called AC-3) and DTS, which are now common on DVD titles, first became available on Laserdisc, and Star Wars: Episode I (1999) which was released on Laserdisc in Japan, is among the first home video releases ever to include 6.1 channel Dolby Digital EX Surround. Unlike DVDs, which carry Dolby Digital audio in digital form, Laserdiscs store Dolby Digital in a frequency modulated form within a track normally used for analog audio. Extracting Dolby Digital from a Laserdisc required a player equipped with a special "AC-3 RF" output and an external demodulator in addition to an AC-3 decoder. The demodulator was necessary to convert the 2.88 MHz modulated AC-3 information on the disc and convert it into a 384 kbit/s signal that the decoder could understand. DTS audio took the place of the PCM audio tracks, and required only a direct connection via Optical Audio cable and a decoder to be heard.

At least where the digital soundtracks were concerned, the level of sound quality was unsurpassed at the time, but the quality of the analog soundtracks varied greatly depending on the disc, and sometimes on the player. Many early and lower-end LD players had poor analog audio sections, and many early discs had poor analog audio tracks, making Digital soundtracks in any form most desirable to serious enthusiasts once they became available. Early Discovision and Laserdisc titles lacked the digital audio option, but many of those movies received digital sound in later re-issues by Universal, and the quality of analog audio tracks generally got better as time went on. Many discs that had originally carried old analog stereo tracks received new Dolby Stereo and Dolby Surround tracks instead, often in addition to a digital track, helping boost sound quality. In addition many later discs have no analog audio track at all, instead offering the choice of the PCM digital audio track or Dolby Digital.

Comb Filters

Many Laserdisc players manufactured from the late 1980s through the time of the format's death had both composite (red, white and 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, while using the composite outputs forced the player to rely on the comb filter of the display device. Although using the S-Video connection was often considered to yield superior results in the late 80s and early 1990s, most of today's mid and high level television sets contain better comb filters than the vast majority of players were equipped with. In these instances, where a player is being used with a more modern display, using the composite output and allowing the display device's internal comb filter to do the work often yields better results.

Laserdisc vs. VHS

LD had a number of advantages over VHS. It featured a far sharper picture with a horizontal resolution of 400 lines for NTSC and 440 lines for PAL discs, while VHS only offered 250 lines. They could handle analog and digital audio, where VHS was analog only, and they could store multiple audio tracks. This allowed for extras like director's commentary tracks and other features to be added on to a film, creating "Special Edition" releases that would not have been possible with VHS. The 1984 Criterion Collection edition of Citizen Kane is generally credited as being the first of the "Special Edition" releases, and for setting the standard by which future SE discs were measured. Disc access was random and chapter based, like DVDs, meaning that one could jump to any point on a given disc very quickly (depending on the player and the disc, within a few seconds at the most), compared to VHS which would require tedious rewinding and fast forwarding to get to specific points. This instant seeking also made it possible for a new breed of laserdisc-based video arcade games, beginning with Dragon's Lair, to be born. Moreover, because the discs are read optically instead of magnetically, no contact needs to be made between the player and the disc, other than for the player's clamp that holds the disc in place as it's spun and read. As a result, the discs don't wear as a result of playback like VHS tapes do and properly-manufactured LDs will theoretically last beyond one's lifetime. They were also cheaper to manufacture because they lack the moving parts and plastic outer shell that are necessary for VHS tapes to work.

Unfortunately the format was not without its disadvantages. The discs were 30cm (12 inches) across, were heavy, cumbersome and much easier to damage than a VHS tape and didn't allow for home users to record onto them. And despite their massive storage capcity, the space consuming analog video data LDs carried severly limited how much video could be stored on them; depending on if it were a CLV or CAV disc, each side of a given disc was limited to holding either 30 (CAV discs) or 60 minutes (CLV discs) of data. After one side was finished playing, the disc would need to be flipped over in order to continue watching the film. Many players, especially units built after the mid-1980s, could this automatically by rotating the optical pickup to the other side of the disc, but except in high-end models with a pre-read buffer, this was accompanied by a pause in the movie while the sides changed. In addition, if the movie was longer than what could be stored on 2 sides of a single disc, swapping to a second disc would be neccesary at some point during the film. To make matters worse, many early laserdiscs were not manufactured properly. Sometimes a substandard adhesive was used to sandwich together the two sides of the disc, causing the disc to delaminate slightly and allowing oxygen to cause the metallic part of the discs to oxidize. This eventually destroyed the disc, a process known as "laser-rot" among LD enthusiasts. Early CDs suffered similar problems, including a notorious batch of defective discs manufactured by Philips-DuPont Optical in Europe during the early 1990s.

Laserdisc vs. DVD

It is interesting to note that the differences between LD technology and DVD have led some videophiles to prefer LD. Laserdiscs use only analog video and almost always carry some form of analog audio. Many purists believe that analog media is capable of higher quality than digital A/V carriers such as CD and DVD, and early DVD demo discs often had compression or encoding problems, giving LD proponents fuel for the fire. However, "LD-perfection" is rarely achieved in practice. Only the absolute best LDs, few and far between, exhibit such superior quality in comparison to the newer DVDs, and even then it requires expensive equipment to realize the benefits.

An advantage to the Laserdisc format over DVD is that video is not digitally-encoded and compressed, and therefore does not experience problems such as artifacting (most visible as blockiness during high motion sequences) or color banding (subtle visible lines in gradient areas, such as skies) that can be caused by the MPEG-2 encoding process as video is prepared for DVD. However, the meticulous frame-by-frame tuning of the encoding process coupled with the variable bit-rate technology generally employed on big-budget DVD releases effectively eliminates this, and an optional feature of the MPEG-2 compression standard allows much higher color resolution to eliminate the visible effect of color banding on some high-end home theatre equipment. Some videophiles will continue to argue that Laserdisc maintains a "smoother" more "film like" image while DVD still looks slightly more artificial. Although this may be true, the generally soft and slightly noisy picture seen with most low and mid-level LD players often turns people off, and the point becomes moot.

A disadvantage with the analog nature of Laserdiscs is that most players exhibit a slight but perceivable 30 Hz video flicker, and slight dust and wear on the hardware or disc can degrade video and audio over time. The DVD format, however, does not introduce any flicker, and the format's digital nature and sophisticated error-correction scheme can often produce spotless video/audio from a DVD, even with dust and scratches on the surface. Laserdisc players also suffered a problem known as "crosstalk". The issue came up when the wide wavelength laser inside the player accidentally picked up picture information from a track adjacent to where it was reading on a disc. The added information usually showed up as distortion in the picture. Some players were better at compensating for and/or avoiding crosstalk entirely than others.

Success of the format

The format was not well-accepted outside of videophile circles in North America, but became more popular in Japan. Part of the reason was marketing. In North America the cost of the players and discs were kept far higher than VHS decks and tapes. In Japan, the LD strategy was very similar to the strategy taken by DVD manufacturers early in its life: prices were kept low to ensure adoption, resulting in minimal price differences between VHS tapes and the higher quality Laserdiscs. LD also quickly became the dominant format of choice amongst Japanese collectors of anime, helping to drive its acceptance.

Nonetheless, the Laserdisc format did not allow for recording onto the discs, while the competing video cassette recorder devices could record using tape cassettes. Combined with the cumbersome disc size and high North American prices for both players and media, the format was doomed to obscurity. When they were first introduced, laser discs were believed to be what would later be referred to as disruptive technology, a promise they failed to fulfil. Compact Discs and DVDs were to be disruptive instead.

Although the Laserdisc format has been completely supplanted by DVD, and new players are no longer sold outside Japan, many LDs were considered definitive releases of movies and are still highly coveted by movie enthusiasts. Boxed multi-disc LD editions of several films are prized as collector's items. There are many films that are only available on LD, or only on LD and lower-quality VHS. As well, there are various films which are available on DVD as well as LD, but the LD version is preferred for some reason. There are many cases in which the LD version of a particular film due to superior mastering or editing. Thus, many LDs are still very much in demand.

Examples include the anime Five Star Stories, which was only released on LD and VHS despite its extreme popularity. Enthusiasts have been known to pay $700 or more for this LD. (Japan's Atlus and North America's ADV Films have since released this movie on DVD in 2003 and 2005 respectively, and thus lowered the demand for the LD version.) Likewise, the LD releases of the original Star Wars trilogy are in high demand among fans and videophiles as, out of all home video releases of the pre-"Special Edition" versions of the films, they offer the highest video and audio quality.

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

It should be noted that the popularity of the LD format in Japan is still great enough that Pioneer continues to manufacture and market two players. The first, the DVL-919, is a DVD/Laserdisc combination unit that was sold for a short while in the U.S. and was subsequently discontinued in 1999 when the format had lost the vast majority of its waning support. In any case, even the least expensive of newer DVD players have generally surpassed the quality and capability of the 919's DVD section and its LD section was never considered better than mediocre by comparison to many other units, even when new. The second of the units offered in Japan, a Laserdisc-only player, model designation CLD-R5, is sold at a lower cost. Although rumor has had it that select Pioneer dealers still have access to leftover, North American specification DVL-919s, and Pioneer has yet to remove the product from their North American website, Pioneer representatives say that the product is officially discontinued and that warranty coverage for 919s will based on the date of manufacturing rather than on the date of sale.

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 LD-S9, HLD-X9 and HLD-X0. All three are manufactured by Pioneer and all three contain technology that was never officially available in North American Laserdisc players. The 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 S9 and X9. It was entirely hand built from hand picked electronics and weighed a massive 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 to be played through.

Laserdisc variations

In 1991, several manufacturers announced specifications for what would become known as "MUSE" Laserdisc. Encoded using technology adopted from "Hi-Vision" (Japanese HDTV) hardware, MUSE discs would operate like standard Laserdiscs but would contain material transferred in High Definition (1080i) widescreen. The MUSE players were also capable of playing standard NTSC format discs and are said to have superior performance to non-MUSE players. 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 and an HDTV. Equipment prices were high, especially for early HDTVs which generally eclipsed $10,000 USD, 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, 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. Several documentaries, including one about Formula One at Japan's Suzuka Circuit were also released.

Towards the end of the format's life, a small number of discs were sold in Japan which contained an anamorphic image technology marketed as "squeeze", effectively the same as the 16:9 anamorphic output from a DVD player. Among the very few films available in this format were Terminator 2, Basic Instinct, and Cliffhanger. Unlike MUSE discs, Squeeze titles required a widescreen television set to display the squeezed image correctly, and they ran at standard resolution, offering 400 horizontal lines (they were mainly NTSC, only two PAL "Squeeze" discs were produced). Widescreen sets cost considerably more than a standard set at the time, which played a major part in why the format never caught on.

"LD singles" which are 18 cm (approx. 8", the same size as a 45-RPM record) across rather than the full 30 cm (approx. 12") size, were also published. LD singles only contained a few minutes of video, enough for a music video or two. They are much rarer than the full-size LDs, especially in North America.

Other forms of "single"-style discs that were playable on laserdisc players were 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. CD-Vs are not to be confused with Video CDs, which are all digital, and can only be played on computers, CD-i players, DVD players, and later-model laserdisc players (such as the DVL series from Pioneer) that can also play DVDs. 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. Both CD-V and VSD used a 5-inch disc, much like audio CD.

Some laser discs, called "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.

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 (enroute, possibly, to a new DVD based format).

Pioneer also marketed a format similar to LD+G, called LD-ROM. It was used by Pioneer's LaserActive interactive laserdisc player/video game console introduced in 1993, and contained analog video in combination with digital data. LD-ROM was used for several games that could be played on the LaserActive player/console.

Missing image
CRVDisc.jpg
A CRV Disc with a VHS tape for size comparison
Another type of video media, CRV Disc, or "Component Recordable Video Disc" were available for a short time, mostly to professionals. CRV discs resemble early PC CD-ROM caddies with a disc inside resembling a full sized LD. CRV discs existed as both pre-recorded releases and also as blank media that could be recorded once (WORM, like CD-R) on each side. CRV was rarely used by the consumer due to the high cost of the equipment and media, and were used largely for backup storage in professional/commercial applications.

External links

fr:Laserdisc nl:CD-Video ja:レーザーディスク sv:Laserdisc

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