Laserdisc
The Laserdisc or LD was the first commercialized optical disc storage system, and was used primarily for playing movies. 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 bought a majority stake in the format and marketed LaserDisc in the second half of the 1980s.
During its development, the format was known as "reflective optical disc video system" until MCA (Music Corporation of America), owner of the patent, renamed it Disco-Vision in 1969. It would later be changed again the name of the format to DiscoVision.
Sales of Laserdisc players and discs began in late 1978. MCA owned the rights to the world's largest catalog of movies, and they distributed them under this format. Pioneer Electronics, around the same date, began manufacturing printable discs and players under the name Laser DiscoVision. By the year 1981, LaserDisc was the name that finally stuck for this format.
MCA also made records for other celluloid companies apart from the Universal Studios with which it had been associated.
The format has also been known as LV (LaserVision, registered trademark of Philips). Their players are sometimes also referred to as VDPs (Video Disc Players).
History
Laserdisc technology uses a transparent disc; it was invented by David Paul Gregg in 1958 (and patented in 1961 and 1990). Prior to 1969, Philips had developed a reflective mode video disc that had major advantages over the transparent. MCA and Philips decided to join forces. The first public demonstration of the videodisc was in 1972. The Laserdisc became commercially available in Atlanta on December 15, 1978, two years after the first VHS VCR and five years before the appearance of the CD, which is based on the laserdisc technology. Philips produced the players and MCA the discs. The cooperation between Philips and MCA was not successful, and was discontinued after a few years. Several of the scientists responsible for the initial research (Richard Wilkinson, Ray Deakin and John Winslow) founded the Optical Disc Corporation (now ODC Nimbus), a company that is today the world leader in optical discs.
The first Laserdisc title released in the US was Tiburón (Jaws on MCA DiscoVision) in 1978. The last two were Sleepy Hollow and Bringing out the Death in 2000, for Paramount. A dozen more titles were released in Japan by the end of 2001. The last Hong Kong film released on Laserdisc format was Tokyo Raiders.
It is estimated that in 1998 there were Laserdisc players in about 2% of households in the United States of America (about 2 million, compared to 85 million VCRs). By comparison, in 1999, there were players in 10% of households in Japan (more than four million). Laserdisc has been completely replaced by DVD in the American retail market, as neither the players nor the software are produced there. It has retained its popularity with American collectors and, to a greater degree, in Japan, where the format was better supported and more commonplace in everyday life. In Europe Laserdisc has always been an obscure format. The format, however, was chosen by the British Broadcasting Corporation (BBC) for the BBC Domesday Project in the mid-1980s, a school project to mark 900 years of the original Domesday Book in England.
The first appearance of a recognizable Laserdisc was in the movie Airport 77: the plane's owner (James Stewart) congratulates his grandson on a bulky vintage Laserdisc.
Physical description
With a certain resemblance to an audio CD but the size of a vinyl album, Laserdiscs, dedicated to films, measured 30 cm in diameter, and consisted of two single-sided aluminum discs glued together. Laserdisc is an analog format, unlike modern CDs or DVDs which are digital formats.
Both formats have indentations and regions forming the structure of the disc. On a CD or DVD these marks stand for binary numbers. In a Laserdisc, frequency modulation is used to obtain a carrier wave that is encoded by pulse width modulation, to create the slits and regions. Laserdiscs have direct access similar to that of CDs and DVDs.
The most common size of the Laserdisc was 30 centimeters (12 inches), a diameter that allowed 30 minutes per side in CAV (Constant Angular Velocity) format or 60 minutes in CLV (Constant Linear Velocity) format. There were also 18-centimetre Laserdiscs that allowed 20 minutes per side (CLV); these discs were used for videos. There was also a 12-centimeter (5-inch) Laserdisc, just like an audio CD.
Audio
Audio could also be stored in both analog and digital formats, and in any variety of audio encoding formats.
NTSC discs could carry two analog sound tracks, plus three uncompressed PCM digital audio tracks, which were CD-quality (2-channel, 16-bit, 44.1 kHz sample rate for PAL and 44.056 kHz for PAL). NTSC, and a signal-to-noise ratio of 96 dB).
PAL records could carry a couple of sound tracks, both analog and digital; in the United Kingdom the term LaserVision is used to refer to discs with analogue audio, while Laserdisc is used for digital audio discs.
Dolby Digital (also called AC3) and DTS, now common on DVD, were first available on Laserdisc, and Star Wars: Episode I (1999), which was released in Japan on Laserdisc, is the first home video release in include Dolby Digital EX Surround 6.1. Laserdiscs store Dolby Digital in FM form on a track normally used for analog audio. Extracting Dolby Digital from a Laserdisc requires a player equipped with a special AC3 RF output and an external demodulator in addition to an AC3 decoder. The demodulator was needed to convert the 2.88 MHz modulated AC3 data on the disc into a 384 kbit/s signal that the decoder could handle. DTS audio, when it became available, replaced digital soundtracks; listening to DTS audio only required an optical digital audio connection to a DTS decoder.
At least where the digital soundtracks were inserted, the sound quality was second to none, but the quality of analog soundtracks varied wildly depending on the disc and sometimes the player. Many of the earlier and cheaper LD players had poor analog audio sections. Early titles on DiscoVision and Laserdisc lacked the digital sound option. Many discs that had carried stereo analog sound tracks received the new Dolby Stereo and Dolby Surround tracks. Later, the records also applied the CX Noise Reduction system, which improved the signal-to-noise ratio of analog audio. In addition many later PAL discs did not have analog audio but had the possibility to choose between PCM and Dolby Digital digital sound.
Both AC3 and DTS Surround audio were clumsily implemented onto Laserdisc. If your player didn't have an AC3 decoder, stereo digital tracks were the next most attractive option. If the player did not support digital tracks or the disc did not include digital tracks, the only alternative was to downgrade to a monophonic presentation on the left analog track. With a DTS disc, the PCM digital tracks weren't available, so if there wasn't a DTS decoder either, the only alternative was to downgrade to the stereo analog tracks.
Usually, only one surround sound option was embedded in a Laserdisc (Dolby Surround, Dolby Digital, or DTS). Both analog and digital tracks are capable of carrying Dolby Surround-encoded information (also depends on the manufacturer), and given a Dolby Surround-encoded source, Laserdisc players and surround sound processors that implement Dolby Pro Logic are capable of give superior surround sound output to those who only decode Dolby Surround.
Formats
- Discs CAV (“constant angular velocity”)—or standard playback discs—supported some unique features such as the freezing of the image, the variable slow motion and: reverse reproduction. The CAV discs were made to rotate at a constant rotational speed during playback, reading a frame for each spin. Thus, 54 000 individual frames or 30 minutes of audio/video could be stored on one side of a CAV disc. Another unique attribute for CAV was to reduce the visibility of ambiguities between adjacent tracks. CAV was used with lesser: frequency than CLV, reserved for special editions of feature films with extra material and special effects. One of the most remarkable advantages of this format was the ability to refer to each:photogram of a film directly by the individual number of the frame (an interesting feature for students intrigued by the study of assembly errors, continuity, etc.).
- Discs CLV (“constant linear velocity”)—or long-lasting discs—do not have the “trick play” feature of the CAVs, offering reproduction only for those: Laserdisc players that included a digital frame memory. These Laserdisc players could add features normally not available on CLV discs such as reproduction to: variable speed forward, backward, and pause as a VCR. CDs encoded with CLV could store 60 minutes of audio/video per face, or 2 hours per disk. For less-length movies: than 120 minutes, it meant that they could be stored on a single disc, reducing the cost of the film and eliminating the annoying exercise of getting up to change disk.
- Discs CAA (“constant angular acceleration”). In the early 1980s, due to problems with ambiguous distortion over Laserdisc:CLV, Pioneer presented the CAA format for long-lasting discs. The constant angular acceleration is very similar to the constant linear speed except for the fact that CAA changes the angular rotation: from the disc in a controlled way rather than gradually slowing down as when a CLV disk is read. With the exception of 3M/Imation, all Laserdisc manufacturers adopted the CAA coding scheme, although many manufacturers manufactured CAA discs with the CLV acronyms on packaging.
Players
Laserdisc players made in the late 1980s had both composite (RCA connectors) and S-Video output on the rear panel. When the S-Video connector was used, the player had to use its own internal peak filter, designed to help reduce noise in images by separating luminance from chrominance —transferred independently on this type of connector—, while using the composite outputs forced the player to rely on the display device's peak filter. Using S-Video connection often produced superior results.
Combi Player: In 1996, the first model of DVD/LD combi player and Pioneer's first DVD player (DVL – 9) came out in Japan. Although DVD/LD combi players offered competent LD performance, they lost importance compared to LD plus players. The latest DVD/LD player, the DVL-919, is still sold in the US However, it has not been actively marketed since the late 1990s. The DVL-919 supports DTS output. The DVD part of the DVL-919 is average by modern standards, and does not support progressive scan (480p). But still it is a component product. The LD part, even though it is competent, is of lower quality than that of the first LD players.
Latest Generation Japanese Players: Japanese players are considered better for their high quality features and playability than North American ones, they are occasionally imported by some LD enthusiasts. Some player models are the CLD-R7G, LD-S9, HLD-X9, and HLD-X0, all of which are made by Pioneer and have technology never available in North American players. The first three share an advanced ridge filter, allowing them to have a huge picture quality advantage over other LD players when using the S-Video connection. This peak filter system is unique and possibly the finest peak filter used to date for any AC powered device; even today, it is still used in high-end CRT televisions from Mitsubishi and Pioneer. In addition to their advanced ridge filter system, the HLD-X9 featured an accelerated infrared laser that significantly reduced image ambiguity and noise levels compared to players using a traditional infrared laser. The HLD-X9 is, just like a properly equipped MUSE player, capable of playing high-definition Laserdiscs, called MUSE or Hi-Vision discs in Japan. The HLD-X0 model is already a MUSE player. The X9 is the most popular model because it incorporated the newest ridge filter and was capable of playing both sides of discs without manually changing sides of the disc.
Comparison with VHS
LD had several advantages over VHS. LD had a sharper image, with a horizontal resolution of 400 lines for NTSC and 440 lines for PAL, while VHS only had 240 lines or S-VHS which reached 420 lines in 1987. It could interpret both analog and digital audio. while VHS could only analog. NTSC discs could store multiple sound tracks. This allowed extras such as director's commentary and other things to be added to a film, leading to special editions that were not possible with VHS. Disc access was random and chapter-based, in the same way as the DVD format, ie one could jump to any point within a disc very quickly (depending on player and disc, in a few seconds). By comparison, VHS would require tedious rewinding and fast forward playback to get to a certain point. Laserdiscs were cheaper to manufacture than videotapes because they lacked the plastic cover and moving parts that are necessary for VHS tapes to work (a VHS tape typically has at least 14 parts including the tape itself. A Laserdisc only has one part, with five or six layers).
In addition, because discs are read optically rather than magnetically, no physical contact is necessary between the player and the disc, except for the clamp on the player that holds the disc in its center as it rotates to be read. As a result of this, playback does not adversely affect the information stored on the discs, and Laserdiscs will theoretically last longer than VHS tapes. On the contrary, a VHS tape keeps all the images and all the audio information on its magnetic layer that rubs against the heads directly, producing progressive wear with each use. Also, the tape is thin and delicate, and it is easier for some mechanism of the player (especially low quality models) to mistreat the tape and can damage it by making scratches or even ruining it completely.
Disadvantages
The size of the disc was excessive even for the time and the cost of its players was very high at the time of its commercialization.
Deterioration of the Laserdisc
Many early Laserdiscs were not manufactured properly; sometimes a very poor quality adhesive was used to join both sides of a record. The adhesive contained impurities that could penetrate the layer separating it from the reflective substrate and chemically attack it, causing it to oxidize and lose its reflective characteristics. This was a problem that was dubbed "Laserdisc Rot" (or "LaserRot”) among LD enthusiasts. Early CDs suffered from similar problems in the early 1990s.
Comparison with DVD
Differences between LD and DVD technologies have led some videophiles to prefer LD. Laserdiscs use only analog video and carry some analog audio most of the time. "LD Perfection" it is rarely achieved in practice. Only the best LDs have higher quality compared to newer DVDs, and even in such cases the most expensive playback equipment is necessary to get the most out of these Laserdiscs.
An advantage of the Laserdisc format over DVD is that the video is not simply digitally encoded and compressed, and does not experience problems such as macroblocking or contrast banding (visible lines in sloping areas, such as sky or spotlight beams). which may be caused by the MPEG-2 encoding process when the video is prepared for DVD. Fortunately, however, the meticulous frame-by-frame tuning in the encoding process along with the bit-range technology generally employed in big-budget DVD releases effectively eliminates this, and an optional feature of the MPEG- 2 allows the highest color resolution to eliminate the visible effect of the color streak on the reproduction background. Some videophiles continue to argue that Laserdisc maintains a greater amount of smooth image like a movie film, unlike DVD which still looks slightly more artificial.
One downside to the analog nature of Laserdisc is that most players experience slight but noticeable 25 or 30 Hz video flicker. Dust and scratches on the face of a disc can cause some problems that can affect to the quality of the video and possibly also to the percentage of disc played correctly by the player. Poor hardware calibration can also play a role in degrading video and sound quality, as well as playback accuracy. The DVD format, however, does not introduce any flicker if the player performs a progressive scan on the equipment, in addition the digital nature of the format and the sophisticated error rectification scheme make it possible to play it with optimal quality, even with dust and dust. stripes.
Laserdisc players suffered from a problem known as "Crosstalk" (ambiguity) on long-playing records. However, the crosstalk problem could also exist on poorly manufactured CLV Laserdiscs or discs that were excessively warped. This problem occurred when the player's optical laser was also reading the data from the track adjacent to the one it was actually reading. The added information resulted in a distorted image. Some players were better at compensating for and/or completely avoiding crosstalk than others, as long as the crosstalk was caused by the disc and not the player. However, there is no crosstalk distortion on Laserdisc CAV since the rotational speed never changes. But, if the player's calibration is off or if the CAV disc is faulty, other issues affecting performance might exist, such as "Laser Lock" (Laserdisc crash), a problem where the player reads the same track and therefore the same two fields for a frame over and over again, causing the image to freeze as if paused.
Laserdisc is a composite video format: luminosity (brightness information) and chromatic information (color information) are transmitted in one signal, and it is the responsibility of the receiver to separate them. Although good comb filters can do a good job, these two signals cannot be totally separated. On a DVD the signals are stored separately, as a result we get their high fidelity particularly in extreme strong colors or places with a lot of detail, particularly if there is moderate movement in the picture. However, this is also true of low-contrast details like skin tones, where ridge filters almost inevitably blur the detail a bit. The image resolution on DVD is higher than on Laserdisc. Most DVD players allow an anamorphic transfer of a 16:9 movie.
Another very important advantage of DVD over Laserdisc was the playback quality of LDs, which was a function of the quality of the player (as with analog).
Reception
The format was not very well received outside of a group of North American videophiles, but it became very popular in Japan. In the US, players and records cost more than VHS tapes and players. In Japan, the LD strategy was very similar to the strategy taken by early DVD manufacturers: low prices to ensure acceptance, resulting in minimal price difference between VHS tapes and high-quality LDs. Laserdisc also quickly became the dominant format within the Japanese anime collective, thus helping its rapid acceptance. Also in Hong Kong, although retail LD prices were relatively high, they became very popular during the 1990s before the introduction of VCDs and DVDs.
However, the Laserdisc format did not allow recording to discs, while competing videotape devices could. Coupled with the inconvenience of disc size and high North American prices for both players and media, the format was doomed.
Although the Laserdisc has been nearly replaced by the DVD entirely, many LDs are still highly sought after by celluloid enthusiasts. This is largely because there are so many movies that are still only available in this format. Also, there are some movies that are available on both DVD and LD, but some still prefer the LD version.
Variants
- Laserdisc-ROM: In the early 1980s, Philips developed a LaserVision player model adapted for a computer interface, giving it the name "Professional". Connected to a PC could be used for viewing images or information for educational or archive purposes, for example thousands of medieval manuscripts scanned. This strange device could be considered an equivalent, very early, of a CD-ROM.
- MUSE LD: In 1991, some manufacturers announced the technical specifications for what could be known as MUSE Laserdisc. Using to codify NHK’s “Hi-Vision” MUSE TV system, MUSE discs should operate under Laserdisc standard but should also be able to store 1125 high-quality video lines (1035 visible lines) with a 5:3 ratio. MUSE players were also able to play disks in NTSC format. MUSE players had some worthwhile advantages over Laserdisc players, including a red laser with a much closer wavelength than normal players. The red laser was able to read through the defects of the disk as stripes and even a slight laserRot of the disk that caused in most of the other players that the reproduction stood, cropped or finished. Crosstalk did not affect MUSE discs, even the narrow wavelength of the laser allowed virtual removal of the crosstalk with normal disks. To view MUSE encoded discs, it was necessary to have a MUSE decoder in addition to a player and a TV. Equipment prices were high, especially for the first high-definition televisions, $10 000, and even in Japan, the MUSE market was tiny.
- Picture discs: the discs for images had one side with the logo or any other printed image on one side, the other to store the data. They only had information on one side.
- LD+G: Pioneer Electronics, one of the biggest supporters and investors in the format, was also deeply involved in the karaoke market in Japan, and used Laserdisc as a storage medium for music and additional content, such as graphics. The format was called LD+G. While some companies produced titles in Laserdisc, others, which were covering the entire market, developed on CD+G (a new format based on DVD), and LD+G fell into disuse.
- LaserActive: Pioneer also commercialized a format similar to LD+G, called LD-ROM. It was used by LaserActive interactive and video consoles released in 1993 by Pioneer, and contained analog video and audio along with digital data (where the sound tracks were digital like those of a normal Laserdisc).
- Squeeze LD: with the launch of 16:9 televisions in the mid-1990s, Pioneer and Toshiba decided that it was time to use the advantage of this format. Squeeeze LD were Laserdisc that were reproduced with a bandwidth range 16:9. This format had the advantage of improving the normal Laserdisc vertical resolution by 33%. A similar process was used for DVDs. Unlike DVD players, few LD players had the ability to dismantle the image. This way if the Squeeze LD was reproduced on a 4:3 television the image would be distorted.
- Recordable formats: another type of video device, CRVdisc (Rememberable Video Disc), was available for a short time, mainly for professionals. Developed by Sony, CRVdisc looked like a CD-ROM PC with a large LD disk. The CRVdiscs were "white" and could be recorded once for each face (such as CD-R disks). CRVdisc were rarely used by the on foot consumer due to its high cost. It was used largely for the storage of backups of professional or commercial applications.
Another recordable Laserdisc format that is fully compatible for playback with regular Laserdiscs (as opposed to CRVdisc) is RLV, or Recordable LaserVision. It was developed and marketed by the Optical Disc Corporation (ODC, now ODC Nimbus) in 1984. RLV discs, in the same way as CRVdisc, are also a WORM technology, and function exactly like a CD-R. RLV discs look almost exactly like normal Laserdiscs, and can be played on any LD player after being recorded. The only difference that an RLV disc has over Laserdiscs is its reflective purple-violet color resulting from dye adhered to the reflective layer of the disc to make it recordable. The color of RLVs looks almost exactly like the purple color of some DVD-Rs and DVD+Rs.