Laserdisc

The optical recording technology using light-transmitting media was developed ^{[1] by} David Paul Gregg in 1958 (and patented in 1961 and 1990) ^{[2] [3]} .

In 1969, Philips created the LaserDisc video system, which was already operating in the reflected light mode and had more advantages over the “backlight” method. The MCA and Philips joined forces to showcase the first video disc in 1972 .

The first laserdisc went on sale December 15, 1978 in Atlanta - two years after the VHS format VTRs appeared on the market (and four years before the CD , also based on LaserDisc technology). The first laser disk to go on sale in North America was the MCA DiscoVision in 1978, the movie Jaws . The latest are the Paramount films Sleepy Hollow and Resurrecting the Dead , released in 2000 . In Japan, no less than a dozen films were published until the end of 2001. The last Japanese film released in LaserDisc format was Tokyo Raiders .

In 1987, the hybrid technology CD and Laserdisc - CD Video was introduced. The 12 cm disc contained up to 5 minutes of analog video information and 20 minutes of CD-quality digital audio.

Philips manufactured the players, and MCA Records released the discs, but their collaboration was not very successful and ended a few years later. Several technology scientists (Richard Wilkinson, Ray Deakin and John Winslow) have set up Optical Disc Corporation (currently ODC Nimbus ).

In 1998, LaserDisc players were in approximately 2% of American homes (approximately 2 million) ^[4] . For comparison - in 1999 in Japan, this figure was 10% ^[5] .

In the mass sector, LaserDisc completely gave way to DVD , and the production of obsolete discs and players for them was discontinued. Today, the LaserDisc format is popular only with amateurs who collect laser discs with various recordings - films, music, shows. Many enthusiasts claim that the LaserDisc format is capable of transmitting motion phases more naturally than digital video, and in the vast majority of cases, video from LaserDisc looks more comfortable than digital , and there is a reason for this: LaserDisc - analog format, discs recorded without compression of information . In addition, so far ( 2009 ) there are many programs (cinema, music) that have not been released on DVD / BluRay or published in an inferior quality to LaserDisc (for example, Olympia Leni Riefenstahl).

Despite the fact that in Europe LaserDisc was never received, the BBC corporation used it in the mid -1980s in the educational project BBC Domesday Project , dedicated to the 900th anniversary of the English Doomsday Book .

In the USSR

In the USSR and Russia, LD players were represented by the Rus-501 VIDEO and Rus VP 201 models manufactured by the State Ryazan Instrument Plant ; “Amphiton VP 201” produced by the Yaroslavl plant “Mashpribor”, and “Hummingbird VP 101” (1997, a copy of “Philips CDV-496”) manufactured by the Izhevsk Mechanical Plant ^[6] .

Discs for domestic video players in CAV (CCP) and CLV (PLC) systems were produced by the Avangard Leningrad NPO ^[7] .

Unlike Video CDs , DVDs, and Blu-ray Discs, LaserDisc contains analog video in composite representation and sound in analog and / or digital form. The standard laserdisk for home use has a diameter of 30 cm (11.81 inches ) and is glued from two single-sided plastic-coated aluminum discs. Information about the signal is stored in billions of microscopic recesses ( pits ) engraved in the aluminum layer below the surface. The surface acrylic layer (1.1 mm) protects them from dust and fingerprints. To read data from the disk, a low-power laser beam is used, which creates a thin light beam (1 μm in diameter ) through the mirror-optical system on the surface of the disk and, being reflected , enters the photosensor and is then transmitted as a high-density encoded audio / video signal for subsequent playback ^[8] .

Since digital encoding ( video compression ) was either unavailable or impractical in 1978, three methods of recording compression were used based on changes in disk rotation speed:

• CAV ( Eng. Constant Angular Velocity - constant angular velocity (as when playing a gramophone record )) - standard video discs ( Eng. Standard Play ), supporting functions such as freeze frame , variable slow-motion playback forward and backward ^[9] . CAV disks during playback have a constant rotation speed (1800 rpm for the NTSC standard (525 lines) and 1500 rpm for the PAL standard (625 lines)) ^[8] , and one frame is read per revolution. In this mode, 54,000 individual frames — 30 minutes of audio / video material — can be stored on one side of the CAV drive. CAV was used less often than CLV, mainly for special editions of feature films, for bonus materials and special effects. One of the advantages of this method is the ability to jump to any frame directly by its number. Random access and the freeze-frame function allowed manufacturers to create simple interactive video discs by placing separate static images on the disk, in addition to video materials ^[10] .
• CLV ( Eng. Constant Linear Velocity - constant linear speed (as when playing CDs )) - long-playing video discs ( Eng. Extended Play ) do not have special CAV-disc playback capabilities ^[9] , offering only simple playback on all Laserdisc players, except for high-end players that have a digital still image function. These players can add new features that are not usually available for CLV discs, such as playing forward and backward at variable speed, and pause like on tape recorders. Gradually slowing down the rotation speed (from 1800 to 600 rpm) ^[8] , CLV disks with a constant linear speed can store 60 minutes of audio / video material on each side, or two hours on a disk. Films lasting less than 120 minutes could fit on one disc, thereby reducing the cost of one movie and eliminating the distraction from viewing the need to replace the disc with the next, at least for those who had a two-way player. The vast majority of releases were available only in CLV (several items were released partially CLV, partially CAV.
• CAA ( English Constant Angular Acceleration - constant angular acceleration ). In the early 1980s, due to crosstalk problems on long-playing CLV laser discs, Pioneer Video introduced CAA formatting of long-playing laser discs. Coding with constant angular acceleration is very similar to coding with constant linear speed, except that in CAA there is an instant decrease in speed with an angular shift by a certain step, instead of a gradual deceleration at a steady pace, as when reading CLV disks. With the exception of 3M / Imation, all Laserdisc manufacturers have adopted a CAA coding scheme, although the term has rarely (if ever) been used on consumer packaging. CAA coding significantly improved image quality and significantly reduced crosstalk and other tracking issues.

Sound

The first laser discs introduced in 1978 were completely analogue , the sound was encoded using frequency modulation , but with the development of the format, digital stereo sound was added in the format of an audio CD (some devices had an S / PDIF interface - both optical and coaxial - to connect an external DAC , and later a DTS decoder), as well as in multi-channel formats - first, even before Dolby Surround 3 / 1.0 digital audio (could be recorded in analog and digital form and had backward compatibility with stereo systems), and then in 3 / 2.1 form max Dolby Digital (replacing one hardware analog channel and requiring an external RF decoder with multi-channel analog or S / PDIF output, which was sometimes built into expensive AV receivers of that era) and DTS (similar to the DTS-CD format, this track supplanted PCM stereo , and with old players it was perceived as an ordinary PCM stereo track and sent to the S / PDIF output, if there was one).

In 1985, Pioneer introduced Digital Audio for Laserdisc as a further improvement in the CAA format. In 1985, CAA55 was introduced with a total playback time of 55 minutes on each side for 5 seconds, and video capacity was reduced to solve bandwidth problems when digital audio was turned on. Several titles released between 1985 and 1987 were with an analog sound track only because of the long duration of the film and the desire to save the film on one disc (for example, “ Back to the Future ”).

By 1987, Pioneer was able to overcome technical difficulties and it became possible to encode in CAA60 format, allowing you to increase the disk capacity in total up to 60 minutes 5 seconds. Also, only a few titles have been released, encoded in CAA65, with a capacity of 65 minutes 5 seconds of playback on each side. The final CAA is the CAA70, which could hold 70 minutes of play on each side. For the consumer market, this format was not used.

The following is a comparison list of the resolution of various analog video and TV formats. Only the most common formats are included here, and some values ​​are approximate, as the image quality may vary on different systems and different media. Data are for PAL 625/25 systems and sorted in order of quality improvement.

• 240 TV lines : VHS , Video8
• 280 TV lines: Umatic , Betamax
• 300 TV lines: Super Betamax
• 330 TV lines: analogue broadcasting (the actual resolution obtained strongly depends on the quality of the transmitting and receiving “sides”)
• 400 TV lines: S-VHS
• 420 TV lines: Hi8
• 440 TV lines: S-Video connection
• 440 TV lines: LaserDisc
• 470 TV lines: Betacam SP (prof.)
• 500 TV lines: Enhanced Definition Betamax

It should be understood that in addition to resolution, the level of noise and interference of the video path has a great influence on image quality. The signal-to-noise ratio of the LD video path is approximately 45 dB, i.e., corresponds to S-VHS, while the Beta family of equipment, for example, can reach 60 dB. An image that is clean from interference is perceived to be of better quality even at a lower resolution.

• Video disc
• Cd video
• DVD

• Disk video recording (Russian) // " Technique of cinema and television ": magazine. - 1985. - No. 2 . - S. 66-69 . - ISSN 0040-2249 .

• Disc Formats - LaserDisc (LD )
• The LaserDisc Database - titles database, profiling, marketplace
• The 'Total Rewind' VCR museum, covering Laserdisc and other vintage formats
• The Laserdisc FAQ , (original source )
• MCA DiscoVision History via the Wayback Machine
• The UK Laserdisc Player Archive - includes North American players
• BLAM Entertainment Group - includes Star Wars and Star Trek Laserdisc catalogs and lists of Dolby Digital and DTS equipped titles
• RCA SelectaVision VideoDisc FAQ - also contains some DiscoVision history
• History of the Laserdisc, Terms and a look at some specific players
• Laserdisc Players and Laserdiscs - Formats and Features - eBay UK guide
• Guide to and software for the Matrox 286 / Laserdisc player