SelectaVision
Encyclopedia
The Capacitance Electronic Disc (CED) was an analog video
video disc playback system developed by RCA
, in which video and audio could be played back on a TV set using a special needle and high-density groove system similar to phonograph
records.
First conceived in 1964, the CED system was widely seen as a technological success which was able to increase the density of a long-playing record by two orders of magnitude. Despite this achievement, the CED system fell victim to poor planning, conflicts within RCA, and technical difficulties that stalled production of the system for 17 years until 1981, by which time it was outmoded by the DiscoVision (LaserDisc) and emerging Betamax
and VHS
videocassette formats. Sales for the system were nowhere near projected estimates, and by 1986, RCA had discontinued the project, losing an estimated $600 million in the process. RCA had initially intended to release the SKT425 CED player with their high end Dimensia system in 1984, but cancelled the CED player as part of the system just prior to the release of the Dimensia system.
The format was commonly known as "videodisc
", leading to much confusion with the contemporary Laserdisc
format. Laserdiscs were read optically with a laser beam, whereas CED videodiscs were read physically with a stylus, rather like a conventional gramophone record
. The two systems were mutually incompatible.
The name "SelectaVision
" was RCA's brand name for the CED system. It was also used for some early RCA brand VCRs, and other experimental projects at RCA.
episode entitled "Lum Fong").
The first CED prototype discs were multi-layered, implementing a nickel
substrate within the platter. However, premature failure of the multilayer discs, usually from separation of the layers and resulting in damage to the player if a disc in such condition was played, forced RCA to search for solutions to the problem or alternative materials for constructing the disc. The final disc would be crafted using PVC
blended with carbon to allow the disc to be conductive. To preserve stylus and groove life, a thin layer of silicone was applied to the disc as a lubricant.
CED videodiscs were originally meant to be handled by hand, but during testing, it was shown that people were likely to accidentally touch the signal surface of the disc, causing signal degradation at the touched area. Thus, an idea was developed in which the disc would be stored and handled in a caddy from which the CED would be extracted by the player.
After seventeen years of research and development, the first CED player (model SFT100W) were released in March 1981. A catalog of approximately 50 titles were released at the same time. Fifteen months later, RCA released the SGT200 and SGT250 players, both with stereo sound. Models with remote controls and random access
hit the market in spring and fall, 1983, respectively.
The long period of development — caused in part by political turmoil and a great deal of turnover in the high command of RCA — also contributed to the demise of the CED system. RCA had originally slated the videodisc system for a 1977 release. However, the discs were still not able to hold more than thirty minutes of video per side, and the nickel-like material used by RCA to make discs was not sturdy enough to put into manufacturing. Signal degradation was also an issue, as the handling of the discs was causing them to deteriorate more rapidly than expected, baffling engineers.
RCA had hoped that by 1981 CED players would be in close to 50% of American
homes, but the sales of players continued to drop. RCA attempted to cut the prices of CED players and offer special incentives to consumers, but sales did not recover, and by April of 1984, executives realized that the system would not be as successful as projected and cancelled production of CED players. In a strange twist, sales of the videodiscs themselves were twice the projected rate, so RCA announced that videodiscs would be produced for at least another three years after the discontinuation of players. After this announcement, however, the sale of discs declined severely, causing RCA to abandon disc production after only two years.
The last titles released were The Jewel of the Nile
by CBS/Fox Video
, and Memories of VideoDisc, a commemorative CED given to many RCA employees involved with the CED project, both in 1986.
, 500 rpm for PAL
) and each rotation contains several full frames (four frames for NTSC, three for PAL). This meant that freeze frame was impossible on players without an expensive electronic frame store facility.
A keel-shaped needle with a titanium electrode layer rides in the groove with extremely light tracking force, and an electronic circuit is formed through the disc and stylus. The video and audio signals are stored on the Videodiscs in a composite analog signal which is encoded into vertical undulations in the bottom of the groove, somewhat like pits. These undulations have a shorter wavelength
than the length of the stylus tip in the groove, and the stylus rides over them; the varying amount of air space between the stylus tip and the undulations in the groove under it directly controls the capacitance
between the stylus and the conductive carbon-loaded PVC
disc. This varying capacitance in turn alters the frequency
of a resonant circuit, producing an FM
electrical signal which is then decoded into video and audio signals by the player's electronics.
The capacitive stylus pickup system which gives the CED its name can be contrasted with the technology of the conventional phonograph
. Whereas the phonograph stylus physically vibrates with the variations in the record groove, and those vibrations are converted by a mechanical transducer (the phono pickup) to an electrical signal, the CED stylus normally does not vibrate and moves only to track the CED groove (and the disc surface—out-of-plane), while the signal from the stylus is natively obtained as an electrical signal. This more sophisticated system, combined with a high revolution rate, is necessary to enable the encoding of video signals with bandwidth of a few megahertz, compared to a maximum of 20 kilohertz for an audio-only signal—a difference of two orders of magnitude. Also, while the undulations in the bottom of the groove may be likened to pits, it is important to note that the spacing of vertical wave crests and troughs in a CED groove is continuously variable, as the CED is an analog
medium
. Usually, the term "pits," when used in the context of information media, refers to features with sharply defined edges and discrete lengths and depths, such as the pits on digital
optical media such as CDs and DVD
s.
In order to maintain an extremely light tracking force, the stylus arm is surrounded by coils which sense deflection, and a circuit in the player responds to the signals from these coils by moving the stylus head carriage in steps as the groove pulls the stylus across the disc. Other coils are used to deflect the stylus, to finely adjust tracking. This system is very similar to—yet predates—the one used in Compact Disc
players to follow the spiral optical track, where typically a servo motor moves the optical pickup in steps for coarse tracking and a set of coils tilts the laser lens for fine tracking, both guided by an optical sensing device which is the analogue of CED stylus deflection sensing coils. For the CED player, this tracking arrangement has the additional benefit that the stylus drag angle remains uniformly tangent to the groove, unlike the case for a phonograph tonearm in which the stylus drag angle and consequently the stylus side force varies with the tone arm angle, which in turn depends on the radial position on the record of the stylus. Whereas for a phonograph, where the stylus has a pinpoint tip, linear tracking is merely ideal to reduce wear of records and styli and to maximize tracking stability, for a CED player linear tracking is a necessity for the keel-shaped stylus, which must always stay tangent to the groove. Furthermore, the achievement of an extremely light tracking force on the CED stylus enables the use of a fine groove pitch (i.e. fine spacing of adjacent revolutions of the spiral,) necessary to provide a long playing time at the required high rotational speed, while also limiting the rate of disc and stylus wear.
The disc is stored inside a caddy, from which the player extracts it when it is loaded. The disc itself is surrounded by a "spine", a plastic ring (actually square on the outside edge) with a thick, straight rim-like edge, which extends outside of, and latches into, the caddy. When a person inserts a caddy containing a disc into the player, the player captures the spine, and both the disc and the spine are left in the player as the person pulls the caddy out. The inner edges of the opening of the caddy have felt
strips designed to catch any dust or other debris that could be on the disc as it is extracted. Once the caddy has been withdrawn by the person, the player lowers the disc onto the turntable (which is actually just a hub); the spine is also lowered with it. To start playing the disc, the player spins it up and moves the stylus onto the disc surface.
When Stop is pressed, the stylus is lifted from the disc and returned to its parking location, and the disc and spine are lifted up again to align with the caddy slot. When ready, the slot is unlocked, and the caddy can be inserted and withdrawn by a person, now with the disc back inside.
, Betamax
, and Laserdisc
. The video quality (approx 3 MHz of luma bandwidth for CED) was comparable to a VHS-SP or Betamax-II video, but sub-par compared to Laserdisc (about 5 MHz of luma bandwidth).
CED players were intended to be "low-cost".
Because they have fewer precision parts than a tape player,
a CED player cost at most half as much as videotape recorder to build.
The disks themselves could be inexpensively duplicated, stamped out on slightly-modified audio gramophone record
presses.
Like VCRs, CED videodisc players had features like rapid forward/reverse and visual search forward/reverse. They also had a pause feature, though it blanked the screen rather than displaying a still image; many players featured a 'page mode' during which the current block of four successive frames would be repeatedly displayed.
Since CEDs were a disc-based system, they did not require rewinding. Early discs were generally monaural
but later discs included stereo
sound. (Monaural CED disks were packaged in white protective caddies while stereo disks were packaged in blue protective caddies.) Other discs could be switched between two separate mono audio tracks, providing features such as bilingual audio capability.
Like the Laserdisc and DVD, some CEDs feature random access and that users can quickly move to certain parts of the movie. Each side of a CED disc could be split into up to 63 "chapters", or bands. Two late RCA players (the SJT400 and SKT400) could access these bands in any given order. Unlike its laser-based counterparts, the chapters in a CED are based on minutes of the film, not scenes.
Novelty discs and CED-based games were produced whereby accessing the chapters in a specified order would string together a different story each time. However, only a few were produced before the halt of CED player manufacturing.
technology, CEDs suffered from the fact that they were a phonograph-like contact medium. RCA estimated that the number of times a CED could be played back, under ideal conditions, was 500. By comparison, a clean, laser rot-free laserdisc could, at least in theory, be played an unlimited number of times (although in practice, repeated handling inevitably results in damage). Since the system used a stylus to read the discs, it was necessary to regularly change the stylus in the player to avoid damage to the videodiscs.
Worn and damaged discs also caused problems for consumers. When a disc began to wear, video and audio quality would severely decline, and the disc would begin to skip more. Several discs suffered from a condition called "video virus", where a CED would skip a great deal due to dust particles stuck in the grooves of the disc. However, playing the disc several times would generally solve this problem.
Unlike VHS
tapes, CEDs required a disc flip at some point during the course of most all films, because only sixty minutes of video could be stored per side. If a feature ran over two hours, it was necessary to insert another disc. (In some cases, if a movie's theatrical running time was only slightly longer than two hours—from 120 minutes and a few seconds to 122 minutes—studios would often trim short scenes throughout the movie in order to avoid the expense of issuing two discs.) This problem was not unique to CEDs, as Laserdiscs presented the same difficulty, and some longer features, such as The Ten Commandments
(1956), still required more than one tape or disc in the VHS, Beta, and LaserDisc
formats.
Less significant disadvantages include lack of support for freeze-frame
during pause since CEDs scanned four frames in one rotation versus one frame per rotation on CAV LaserDisc, nor was computer technology advanced enough at the time to outfit the player with a framebuffer
affordably. However, a 'page mode' was available on many players that would allow for those four frames to be repeated in an endless loop.
CEDs were also larger than VHS tapes, thicker than laserdiscs and considerably heavier due to the plastic caddies.
, Sanyo
, Toshiba
, and an in-house player made by Sears, but seven other companies marketed players manufactured by these companies.
plus Paramount and Disney releases.), CBS Video Enterprises (later CBS/FOX Video
) produced the first 50 titles. Eventually, Disney, Paramount Pictures
, MCA
, MGM, Vestron Video
, and other labels began to produce CED discs under their own home video labels, and did so until the end of disc manufacturing in 1986.
Analog video
Analog video is a video signal transferred by an analog signal. An analog color video signal contains luminance, brightness and chrominance of an analog television image...
video disc playback system developed by RCA
RCA
RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
, in which video and audio could be played back on a TV set using a special needle and high-density groove system similar to phonograph
Phonograph
The phonograph record player, or gramophone is a device introduced in 1877 that has had continued common use for reproducing sound recordings, although when first developed, the phonograph was used to both record and reproduce sounds...
records.
First conceived in 1964, the CED system was widely seen as a technological success which was able to increase the density of a long-playing record by two orders of magnitude. Despite this achievement, the CED system fell victim to poor planning, conflicts within RCA, and technical difficulties that stalled production of the system for 17 years until 1981, by which time it was outmoded by the DiscoVision (LaserDisc) and emerging Betamax
Betamax
Betamax was a consumer-level analog videocassette magnetic tape recording format developed by Sony, released on May 10, 1975. The cassettes contain -wide videotape in a design similar to the earlier, professional wide, U-matic format...
and VHS
VHS
The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....
videocassette formats. Sales for the system were nowhere near projected estimates, and by 1986, RCA had discontinued the project, losing an estimated $600 million in the process. RCA had initially intended to release the SKT425 CED player with their high end Dimensia system in 1984, but cancelled the CED player as part of the system just prior to the release of the Dimensia system.
The format was commonly known as "videodisc
Videodisc
Videodisc is a general term for a laser- or stylus-readable random-access circular disc that contains both audio and analog video signals recorded in an analog form...
", leading to much confusion with the contemporary Laserdisc
Laserdisc
LaserDisc was a home video format and the first commercial optical disc storage medium. Initially licensed, sold, and marketed as MCA DiscoVision in North America in 1978, the technology was previously referred to interally as Optical Videodisc System, Reflective Optical Videodisc, Laser Optical...
format. Laserdiscs were read optically with a laser beam, whereas CED videodiscs were read physically with a stylus, rather like a conventional gramophone record
Gramophone record
A gramophone record, commonly known as a phonograph record , vinyl record , or colloquially, a record, is an analog sound storage medium consisting of a flat disc with an inscribed, modulated spiral groove...
. The two systems were mutually incompatible.
The name "SelectaVision
SelectaVision
The Capacitance Electronic Disc was an analog video video disc playback system developed by RCA, in which video and audio could be played back on a TV set using a special needle and high-density groove system similar to phonograph records....
" was RCA's brand name for the CED system. It was also used for some early RCA brand VCRs, and other experimental projects at RCA.
Beginnings and release
RCA began videodisc research in 1964, in an attempt to produce a phonograph-like method of reproducing video. Research and development was slow in the early years, as the development team originally comprised only four men, but by 1972, the CED team at RCA had produced a disc capable of holding ten minutes of color video (a portion of the Get SmartGet Smart
Get Smart is an American comedy television series that satirizes the secret agent genre. Created by Mel Brooks with Buck Henry, the show starred Don Adams , Barbara Feldon , and Edward Platt...
episode entitled "Lum Fong").
The first CED prototype discs were multi-layered, implementing a nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
substrate within the platter. However, premature failure of the multilayer discs, usually from separation of the layers and resulting in damage to the player if a disc in such condition was played, forced RCA to search for solutions to the problem or alternative materials for constructing the disc. The final disc would be crafted using PVC
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
blended with carbon to allow the disc to be conductive. To preserve stylus and groove life, a thin layer of silicone was applied to the disc as a lubricant.
CED videodiscs were originally meant to be handled by hand, but during testing, it was shown that people were likely to accidentally touch the signal surface of the disc, causing signal degradation at the touched area. Thus, an idea was developed in which the disc would be stored and handled in a caddy from which the CED would be extracted by the player.
After seventeen years of research and development, the first CED player (model SFT100W) were released in March 1981. A catalog of approximately 50 titles were released at the same time. Fifteen months later, RCA released the SGT200 and SGT250 players, both with stereo sound. Models with remote controls and random access
Random access
In computer science, random access is the ability to access an element at an arbitrary position in a sequence in equal time, independent of sequence size. The position is arbitrary in the sense that it is unpredictable, thus the use of the term "random" in "random access"...
hit the market in spring and fall, 1983, respectively.
Demise
Several problems doomed the new CED system almost from the start. From an early point in the development of the CED system, it was clear that VCRs and home videotape - with their longer storage capacity and recording capabilities - would pose a threat to the CED system. However, development pushed ahead; to dispose of all the work done at RCA would have cost the company millions of dollars. Once finally released, sales for the new CED system were slow; RCA had expected to sell 200,000 players by the beginning of 1982, but only half had been sold, and throughout 1982 and '83, sales did not improve much.| "...Machiavelli noted that '..there is nothing more difficult to take in hand, more perilous to conduct, or more uncertain in its success, than to take the lead in the introduction of a new order of things...' At videodisc RCA RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor... , I believe these words had special significance..." |
| Dr. Jay J. Brandinger, Vice President, RCA SelectaVision Videodisc Operations, June 27, 1986. |
The long period of development — caused in part by political turmoil and a great deal of turnover in the high command of RCA — also contributed to the demise of the CED system. RCA had originally slated the videodisc system for a 1977 release. However, the discs were still not able to hold more than thirty minutes of video per side, and the nickel-like material used by RCA to make discs was not sturdy enough to put into manufacturing. Signal degradation was also an issue, as the handling of the discs was causing them to deteriorate more rapidly than expected, baffling engineers.
RCA had hoped that by 1981 CED players would be in close to 50% of American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
homes, but the sales of players continued to drop. RCA attempted to cut the prices of CED players and offer special incentives to consumers, but sales did not recover, and by April of 1984, executives realized that the system would not be as successful as projected and cancelled production of CED players. In a strange twist, sales of the videodiscs themselves were twice the projected rate, so RCA announced that videodiscs would be produced for at least another three years after the discontinuation of players. After this announcement, however, the sale of discs declined severely, causing RCA to abandon disc production after only two years.
The last titles released were The Jewel of the Nile
The Jewel of the Nile
The Jewel of the Nile is a 1985 romantic adventure film, and a sequel to the 1984 film Romancing the Stone, with Michael Douglas, Kathleen Turner, and Danny DeVito reprising their roles...
by CBS/Fox Video
CBS/Fox Video
CBS/Fox Video was a home video company formed and established in 1982, as a merger between 20th Century Fox Video, formerly Magnetic Video Corporation, and CBS Video Enterprises....
, and Memories of VideoDisc, a commemorative CED given to many RCA employees involved with the CED project, both in 1986.
How CEDs work
CEDs are conductive vinyl platters that are 30 cm (11.8 in) in diameter. To avoid metric names they are usually called "12 inch discs". The two sides of a CED each have a spiral groove up to 12 miles (19 km) long with a width of about one thirty-seventh that of a phonograph record. The discs rotate at a constant speed during playback (450 rpm for NTSCNTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
, 500 rpm for PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
) and each rotation contains several full frames (four frames for NTSC, three for PAL). This meant that freeze frame was impossible on players without an expensive electronic frame store facility.
A keel-shaped needle with a titanium electrode layer rides in the groove with extremely light tracking force, and an electronic circuit is formed through the disc and stylus. The video and audio signals are stored on the Videodiscs in a composite analog signal which is encoded into vertical undulations in the bottom of the groove, somewhat like pits. These undulations have a shorter wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
than the length of the stylus tip in the groove, and the stylus rides over them; the varying amount of air space between the stylus tip and the undulations in the groove under it directly controls the capacitance
Capacitance
In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...
between the stylus and the conductive carbon-loaded PVC
PVC
Polyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter, a small, flexible tube placed into a peripheral vein in order to administer medication or fluids...
disc. This varying capacitance in turn alters the frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
of a resonant circuit, producing an FM
Frequency modulation
In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...
electrical signal which is then decoded into video and audio signals by the player's electronics.
The capacitive stylus pickup system which gives the CED its name can be contrasted with the technology of the conventional phonograph
Phonograph
The phonograph record player, or gramophone is a device introduced in 1877 that has had continued common use for reproducing sound recordings, although when first developed, the phonograph was used to both record and reproduce sounds...
. Whereas the phonograph stylus physically vibrates with the variations in the record groove, and those vibrations are converted by a mechanical transducer (the phono pickup) to an electrical signal, the CED stylus normally does not vibrate and moves only to track the CED groove (and the disc surface—out-of-plane), while the signal from the stylus is natively obtained as an electrical signal. This more sophisticated system, combined with a high revolution rate, is necessary to enable the encoding of video signals with bandwidth of a few megahertz, compared to a maximum of 20 kilohertz for an audio-only signal—a difference of two orders of magnitude. Also, while the undulations in the bottom of the groove may be likened to pits, it is important to note that the spacing of vertical wave crests and troughs in a CED groove is continuously variable, as the CED is an analog
Analog signal
An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...
medium
Data storage device
thumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....
. Usually, the term "pits," when used in the context of information media, refers to features with sharply defined edges and discrete lengths and depths, such as the pits on digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
optical media such as CDs and DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
s.
In order to maintain an extremely light tracking force, the stylus arm is surrounded by coils which sense deflection, and a circuit in the player responds to the signals from these coils by moving the stylus head carriage in steps as the groove pulls the stylus across the disc. Other coils are used to deflect the stylus, to finely adjust tracking. This system is very similar to—yet predates—the one used in Compact Disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
players to follow the spiral optical track, where typically a servo motor moves the optical pickup in steps for coarse tracking and a set of coils tilts the laser lens for fine tracking, both guided by an optical sensing device which is the analogue of CED stylus deflection sensing coils. For the CED player, this tracking arrangement has the additional benefit that the stylus drag angle remains uniformly tangent to the groove, unlike the case for a phonograph tonearm in which the stylus drag angle and consequently the stylus side force varies with the tone arm angle, which in turn depends on the radial position on the record of the stylus. Whereas for a phonograph, where the stylus has a pinpoint tip, linear tracking is merely ideal to reduce wear of records and styli and to maximize tracking stability, for a CED player linear tracking is a necessity for the keel-shaped stylus, which must always stay tangent to the groove. Furthermore, the achievement of an extremely light tracking force on the CED stylus enables the use of a fine groove pitch (i.e. fine spacing of adjacent revolutions of the spiral,) necessary to provide a long playing time at the required high rotational speed, while also limiting the rate of disc and stylus wear.
The disc is stored inside a caddy, from which the player extracts it when it is loaded. The disc itself is surrounded by a "spine", a plastic ring (actually square on the outside edge) with a thick, straight rim-like edge, which extends outside of, and latches into, the caddy. When a person inserts a caddy containing a disc into the player, the player captures the spine, and both the disc and the spine are left in the player as the person pulls the caddy out. The inner edges of the opening of the caddy have felt
Felt
Felt is a non-woven cloth that is produced by matting, condensing and pressing woollen fibres. While some types of felt are very soft, some are tough enough to form construction materials. Felt can be of any colour, and made into any shape or size....
strips designed to catch any dust or other debris that could be on the disc as it is extracted. Once the caddy has been withdrawn by the person, the player lowers the disc onto the turntable (which is actually just a hub); the spine is also lowered with it. To start playing the disc, the player spins it up and moves the stylus onto the disc surface.
When Stop is pressed, the stylus is lifted from the disc and returned to its parking location, and the disc and spine are lifted up again to align with the caddy slot. When ready, the slot is unlocked, and the caddy can be inserted and withdrawn by a person, now with the disc back inside.
Advantages of CEDs
CED players, from an early point in their life, appealed to a lower-income market more than VHSVHS
The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....
, Betamax
Betamax
Betamax was a consumer-level analog videocassette magnetic tape recording format developed by Sony, released on May 10, 1975. The cassettes contain -wide videotape in a design similar to the earlier, professional wide, U-matic format...
, and Laserdisc
Laserdisc
LaserDisc was a home video format and the first commercial optical disc storage medium. Initially licensed, sold, and marketed as MCA DiscoVision in North America in 1978, the technology was previously referred to interally as Optical Videodisc System, Reflective Optical Videodisc, Laser Optical...
. The video quality (approx 3 MHz of luma bandwidth for CED) was comparable to a VHS-SP or Betamax-II video, but sub-par compared to Laserdisc (about 5 MHz of luma bandwidth).
CED players were intended to be "low-cost".
Because they have fewer precision parts than a tape player,
a CED player cost at most half as much as videotape recorder to build.
The disks themselves could be inexpensively duplicated, stamped out on slightly-modified audio gramophone record
Gramophone record
A gramophone record, commonly known as a phonograph record , vinyl record , or colloquially, a record, is an analog sound storage medium consisting of a flat disc with an inscribed, modulated spiral groove...
presses.
Like VCRs, CED videodisc players had features like rapid forward/reverse and visual search forward/reverse. They also had a pause feature, though it blanked the screen rather than displaying a still image; many players featured a 'page mode' during which the current block of four successive frames would be repeatedly displayed.
Since CEDs were a disc-based system, they did not require rewinding. Early discs were generally monaural
Monaural
Monaural or monophonic sound reproduction is single-channel. Typically there is only one microphone, one loudspeaker, or channels are fed from a common signal path...
but later discs included stereo
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
sound. (Monaural CED disks were packaged in white protective caddies while stereo disks were packaged in blue protective caddies.) Other discs could be switched between two separate mono audio tracks, providing features such as bilingual audio capability.
Like the Laserdisc and DVD, some CEDs feature random access and that users can quickly move to certain parts of the movie. Each side of a CED disc could be split into up to 63 "chapters", or bands. Two late RCA players (the SJT400 and SKT400) could access these bands in any given order. Unlike its laser-based counterparts, the chapters in a CED are based on minutes of the film, not scenes.
Novelty discs and CED-based games were produced whereby accessing the chapters in a specified order would string together a different story each time. However, only a few were produced before the halt of CED player manufacturing.
Disadvantages of CEDs
In comparison to laserdiscLaserdisc
LaserDisc was a home video format and the first commercial optical disc storage medium. Initially licensed, sold, and marketed as MCA DiscoVision in North America in 1978, the technology was previously referred to interally as Optical Videodisc System, Reflective Optical Videodisc, Laser Optical...
technology, CEDs suffered from the fact that they were a phonograph-like contact medium. RCA estimated that the number of times a CED could be played back, under ideal conditions, was 500. By comparison, a clean, laser rot-free laserdisc could, at least in theory, be played an unlimited number of times (although in practice, repeated handling inevitably results in damage). Since the system used a stylus to read the discs, it was necessary to regularly change the stylus in the player to avoid damage to the videodiscs.
Worn and damaged discs also caused problems for consumers. When a disc began to wear, video and audio quality would severely decline, and the disc would begin to skip more. Several discs suffered from a condition called "video virus", where a CED would skip a great deal due to dust particles stuck in the grooves of the disc. However, playing the disc several times would generally solve this problem.
Unlike VHS
VHS
The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....
tapes, CEDs required a disc flip at some point during the course of most all films, because only sixty minutes of video could be stored per side. If a feature ran over two hours, it was necessary to insert another disc. (In some cases, if a movie's theatrical running time was only slightly longer than two hours—from 120 minutes and a few seconds to 122 minutes—studios would often trim short scenes throughout the movie in order to avoid the expense of issuing two discs.) This problem was not unique to CEDs, as Laserdiscs presented the same difficulty, and some longer features, such as The Ten Commandments
The Ten Commandments (1956 film)
The Ten Commandments is a 1956 American epic film that dramatized the biblical story of the Exodus, in which the Hebrew-born Moses, an adopted Egyptian prince, becomes the deliverer of the Hebrew slaves. The film, released by Paramount Pictures in VistaVision on October 5, 1956, was directed by...
(1956), still required more than one tape or disc in the VHS, Beta, and LaserDisc
Laserdisc
LaserDisc was a home video format and the first commercial optical disc storage medium. Initially licensed, sold, and marketed as MCA DiscoVision in North America in 1978, the technology was previously referred to interally as Optical Videodisc System, Reflective Optical Videodisc, Laser Optical...
formats.
Less significant disadvantages include lack of support for freeze-frame
Freeze frame shot
A freeze frame shot is used when one shot is printed in a single frame several times, in order to make an interesting illusion of a still photograph....
during pause since CEDs scanned four frames in one rotation versus one frame per rotation on CAV LaserDisc, nor was computer technology advanced enough at the time to outfit the player with a framebuffer
Framebuffer
A framebuffer is a video output device that drives a video display from a memory buffer containing a complete frame of data.The information in the memory buffer typically consists of color values for every pixel on the screen...
affordably. However, a 'page mode' was available on many players that would allow for those four frames to be repeated in an endless loop.
CEDs were also larger than VHS tapes, thicker than laserdiscs and considerably heavier due to the plastic caddies.
Players
CED players were manufactured by five companies - RCA, HitachiHitachi
Hitachi is a multinational corporation specializing in high-technology.Hitachi may also refer to:*Hitachi, Ibaraki, Japan*Hitachi province, former province of Japan*Prince Hitachi and Princess Hitachi, members of the Japanese imperial family...
, Sanyo
Sanyo
is a major electronics company and member of the Fortune 500 whose headquarters is located in Moriguchi, Osaka prefecture, Japan. Sanyo targets the middle of the market and has over 230 Subsidiaries and Affiliates....
, Toshiba
Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
, and an in-house player made by Sears, but seven other companies marketed players manufactured by these companies.
Media
Upon release, 50 titles were available for the CED; along with RCA (which included the company's partnership with Columbia PicturesColumbia Pictures
Columbia Pictures Industries, Inc. is an American film production and distribution company. Columbia Pictures now forms part of the Columbia TriStar Motion Picture Group, owned by Sony Pictures Entertainment, a subsidiary of the Japanese conglomerate Sony. It is one of the leading film companies...
plus Paramount and Disney releases.), CBS Video Enterprises (later CBS/FOX Video
CBS/Fox Video
CBS/Fox Video was a home video company formed and established in 1982, as a merger between 20th Century Fox Video, formerly Magnetic Video Corporation, and CBS Video Enterprises....
) produced the first 50 titles. Eventually, Disney, Paramount Pictures
Paramount Pictures
Paramount Pictures Corporation is an American film production and distribution company, located at 5555 Melrose Avenue in Hollywood. Founded in 1912 and currently owned by media conglomerate Viacom, it is America's oldest existing film studio; it is also the last major film studio still...
, MCA
Universal Studios Home Entertainment
Universal Studios Home Entertainment is the home video division of Universal Pictures...
, MGM, Vestron Video
Vestron Video
Vestron Video was the main subsidiary of Vestron, Inc., a home video company based in Stamford, Connecticut that was active from 1982 to 1992. It is considered to have been a pioneer in the home video market....
, and other labels began to produce CED discs under their own home video labels, and did so until the end of disc manufacturing in 1986.
Further reading
- Cowie, Jefferson R. Capital Moves: RCA's Seventy-Year Quest for Cheap Labor. Ithaca, N.Y.: Cornell University Press, 1999. ISBN 0-8014-3525-0.
- Daynes, Rob and Beverly Butler. The VideoDisc Book: A Guide and Directory. New York: John Wiley and Sons, 1984. ISBN 0-471-80342-1.
- DeBloois, Michael L., ed. VideoDisc/Microcomputer Courseware Design. Englewood Cliffs, N.J.: Educational Technology Publications, 1982. ISBN 0-87778-183-4.
- Floyd, Steve, and Beth Floyd, eds. The Handbook of Interactive Video. White Plains, NY: Knowledge Industry Publications. 1982. ISBN 0-86729-019-6.
- Graham, Margaret B.W. RCA and the VideoDisc: The Business of Research. (Also as: The Business of Research: RCA and the VideoDisc.) Cambridge: Cambridge University Press, 1986. ISBN 0-521-32282-0, ISBN 0-521-36821-9.
- Haynes, George R. Opening Minds: The Evolution of Videodiscs & Interactive Learning. Dubuque, Iowa: Kendall/Hunt Publishing Co., 1989. ISBN 0-8403-5191-7.
- Howe, Tom. CED Magic: The RCA VideoDisc Collector's Guide. Portland, OR: CED Magic, 1999. ISBN 0-9670013-0-7. (CD-ROM)
- Isailovi´c, Jordan. VideoDisc and Optical Memory Systems. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-942053-3.
- Lardner, James. Fast Forward: Hollywood, the Japanese, and the VCR Wars. (Also as: Fast Forward: Hollywood, the Japanese, and the Onslaught of the VCR.) New York: W. W. Norton & Co Inc., 1987. ISBN 0-393-02389-3.
- Lenk, John D. Complete Guide to Laser/VideoDisc Player Troubleshooting and Repair. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-160813-4.
- Schneider, Edward W., and Junius L. Brennion. The Instructional Media Library: VideoDiscs, (Volume 16). Englewood Cliffs, NJ: Educational Technology Publications. ISBN 0-87778-176-1. 1981.
- Sigel, Efrem, Mark Schubin and Paul F. Merrill. Video Discs: The Technology, the Applications and the Future. White Plains, N.Y. : Knowledge Industry Publications, 1980. ISBN 0-914236-56-3. ISBN 0-442-27784-9.
- Sobel, Robert. RCA. New York: Stein and Day/Publishers, 1986. ISBN 0-8128-3084-9.
- Sonnenfeldt, Richard. Mehr als ein Leben (More than One Life). ?, 2003. ISBN 3-502-18680-4. (In German.)
- Journals:
- The Videodisc Monitor
- Videodisc News
- Videodisc/Optical Disk Magazine
- Video Computing