SCART
Encyclopedia
SCART is a French
-originated standard and associated 21-pin connector for connecting audio-visual (AV) equipment together. It is also known as (especially in France, where the term SCART is practically unknown), 21-pin EuroSCART (Sharp
's marketing term for an attempt to market the connector in the Asian region), Euroconector or EuroAV. In America, another name for SCART is EIA Multiport (an EIA interface).
In Europe, SCART is the most common method of connecting audio-visual equipment together, and has become a standard connector for such devices (even more so than the phono plug
); it is far less common elsewhere in the world. Designed to carry analog standard-definition content, SCART is becoming obsolete with the introduction of new digital standards such as HDMI
, which can carry high-definition
content and multichannel audio
. Yet HDMI does build on some concepts originally developed for SCART; for example, HDMI-CEC is derived from SCART's AV.link
.
The official standard for SCART is CENELEC document number EN 50049-1. SCART is sometimes referred to as the IEC 933-1 standard.
Before SCART came, consumer TV sets did not offer a standardised way of putting in signals other than RF
antenna connectors, and even antenna connectors differed among countries. Assuming other connectors even existed, devices made by various companies could have different and incompatible standards. For example, a domestic VCR could output a composite video
signal through a German-originated DIN-style connector, an American-originated RCA connector
, an SO239 connector, or a BNC connector
.
, VCRs, DVD
players and game consoles
). To achieve this it gathered all of the analogue signal connections into a single cable with a unique connector that made incorrect connections nearly impossible.
The signals carried by SCART include both composite
and RGB (with composite synchronisation) video
, stereo
audio input/output and digital signalling. The standard was extended at the end of the 1980s to support the new S-Video
signals. In addition, a TV can be awakened from standby mode or switched to video mode through a SCART connector.
SCART is bi-directional regarding standard composite video and analog audio. A television set will typically send the antenna audio and video signals to the SCART sockets all the time and watch for returned signals, to display and reproduce them instead. This allows "transparent" set-top boxes, without any tuner, which just "hook" and pre-process the television signals. This feature is used for analog pay TV like Canal Plus and was in the past used for decoding teletext
.
A VCR will typically have two SCART sockets, one connecting to the television set ("up", "primary" or "1"), and another one for the set-top box or other devices ("down", "secondary" or "2"). When idle or powered off, the VCR will forward the signals from the television set to the set-top decoder and send the processed result back to the television set. When a scrambled show is recorded, the VCR will drive the set-top box from its own tuner and send the unscrambled signals to the television set for viewing or simple recording control purposes. Alternatively, the VCR could use the signals from the television set, in which case it would be inadvisable to change channels on the television set during the recording.
The "down" socket can also be used to connect other devices, such as DVD players or game consoles. As long as all devices have at least one "up" and "down" socket, this allows for connecting a virtually unlimited number of devices to a single SCART socket on the TV set. While audio and video signals can travel both "up" to the TV set and "down" to devices farther away from the TV, this is not true for RGB (and non-standard YPBPR) signals, which can only travel towards the TV set.
"Up" and "down" are conventional.
Logically the TV set is the last device of the "up" chain-path (stream) and the first device in the "down" chain path (stream).
Physically the TV is under the device which sits on its top, hence the name set-top-box for the device. Moreover some sockets relative position may enforce the belief that the TV is physically the last in the down direction.
Logically, the TV set is on top and ends the "up" chain-path (stream), translating the electrical info in optic and audio.
From the same logical point of view the info stream, wherever it originates, may need processing such as decrypting (decoding, descrambling) or adding captioning/subtitles. In this case the info stream is sent logically "down" to dedicated function devices. From the last processing device the info stream is sent logically "up" to the TV set, through all the chain-path.
Another case is when the info stream is sent "down" and not expected to be sent back "up", for example when sent to a recorder.
Closing a loop on either "up" or "down" chain-path (stream) may not have useful effects and may create instability.
However, this no longer works when S-Video signals are used. As straight links (RGB Red and Blue up) were re-purposed to carry chrominance information, the S-Video pinouts are different for "up" and "down" SCART connectors. Further, they are often not fully implemented.
Paying attention to the type of socket is essential when handling component RGB/YPBPR/S-video. Damage can be caused to devices incorrectly connected as follows:
Damaging only pin 7 may result in yellow images, due to the missing blue. Likewise damaging pin 11 or 15 may result in purple or blue/green images, due to the missing green or red components (respectively). When using S-video, damaging pin 7 or 15 may result in black-white images due to the missing chroma component ("down" and "up" respectively). Similarly, damaging pins 7 and 15 (PB and PR) while leaving pin 11 (Y) undamaged may result in black-white images when using YPBPR. Damaging more than one of these pins may result in combined effects.
-level granularity. This can also be driven by the use of a "transparent" colour in a teletext page.
The same signal can be used by a satellite receiver
or set top box to signal a VCR that it is supposed to start and stop recording ("pin 8 recording"). This configuration usually requires that the VCR be farther from the TV set than the source, so the signal usually travels "down".
SCART also supports automatic widescreen
switching. This is an extension of the functionality of a pin which previously only indicated to the TV set that an external signal should be displayed. Ideally, a widescreen source should offer three operating modes in order to deal with widescreen signals:
In the first case, the widescreen pin allows to indicate the current signal format, which allows widescreen sets to adjust the image width, and widescreen-capable standard sets to compress the image vertically. In the second case, the widescreen SCART signal is never active and the signal source performs the adaptations itself so that the image has always a standard format as a result. In practice, some sources will assume that the television set is always capable of widescreen functionality and hence never perform the adaptations. Some source will not even issue the widescreen signal or maintain it at the same level all the time. Other sources might offer the option of truncating the sides, but not of letterboxing, which requires significantly more processing. Notably, the circuitry of the early widescreen MAC
standard decoders (e.g. the Visiopass) could not letterbox. The limitations apply mostly to satellite television receivers, while DVD players can always at least letterbox and often zoom.
Some of the most creative usages appeared in analog satellite receivers. The function of decoding hybrid, time-compressed analog-digital MAC
transmissions into RGB and analog audio was akin to making a digital receiver out of an analog one. The D²B pins (10 and 12) were used for communicating with satellite dish
positioners and for driving magnetic polarisers
, before these became incorporated into LNB
s. The daisy-chaining features were used to connect both a Pay TV decoder and a dish positioner/polariser to a single Decoder socket on the receiver.
CENELEC EN 50157-1 introduced AV.link
as a standardised protocol to carry advanced control information between devices. It is a single-wire serial data bus
and allows carrying remote control information and to negotiate analogue signal types (e.g. RGB).
AV.link is also known as nexTViewLink or under different trade names such as SmartLink, Q-Link, EasyLink, etc. It appears as the Consumer Electronics Control channel in HDMI
.
The original SCART specification provided for different cable (cordset) types denoted by a key colour. However, colour coding is rarely used in practice and cables often use different, non-standard configurations.
1 depends on protocol used.
players with SCART sockets output RGB video, which offers far superior picture quality to typical composite signals. However, many players do not have RGB output turned on by default but composite video
—this often has to be set manually in the player's setup menu or via switches on the back of the player.
The Nintendo GameCube
, Wii
, Dreamcast, PlayStation, PlayStation 2
, PlayStation 3
, Xbox
and Xbox 360
can output RGB
, component video
, S-Video
, or composite video
. These consoles come with the standard composite video connector, but the manufacturers and third parties sell connectors for component video hookup and for RGB SCART hookup. Where the Nintendo GameCube and Xbox automatically switch to the proper mode, the PlayStation 2 must be told via a selection in the system menu whether it is to use YPBPR or RGB video. Also, some versions of legacy consoles such as Sega's Mega Drive (Genesis) and Nintendo's SNES
and Nintendo 64
(modified NTSC and early French SECAM versions only) are capable of outputting RGB signals.
† RGB is only available on PAL region
GameCube and Wii consoles, while S-Video is only available on NTSC consoles.
Many older home computers (Amstrad CPC
, later ZX Spectrum
models, Commodore Amiga, Atari ST
, BBC Micro
and Acorn Archimedes
, etc.) output RGB with composite sync suitable for SCART use, but most used varying non-standard DIN plugs. Standard-resolution arcade monitors use RGB signals with a composite sync, which is SCART-compatible.
Maximum SCART cable length is estimated to be about 10 to 15 metres without amplification.
Due to the relatively high voltage used in SCART, "hot plugging" (connecting or disconnecting devices while they are on) is not recommended. Although there is no risk of personal injury, there is the possibility of damaging electronics within the devices if the connector is inserted improperly.
Quality differences exist in SCART cables. While a proper SCART cable uses miniature coax cables for the video signals, cheap SCART cables often use plain wires for all signals, resulting in a loss of image quality and greatly reducing the maximum cable length. A common problem is that a TV outputs a composite video signal from its internal tuner, and this is induced or cross-talked
onto an incoming video signal due to inadequate or non-existent screening on a cheap SCART cable; the result is ghostly images or shimmering superimposed on the incoming signal. To non-destructively verify if a SCART cable uses coax cables, one can unscrew the strain relief at the SCART connector and fold open the plastic shell.
Using higher-quality cables such as those with ribbon cords that have properly shielded coax cables inside might help in reducing a 'ghosting' effect, but it does not always completely eliminate it due to various factors. A more permanent method is to remove pin 19 from the SCART plug that is put into the TV. Pin 19 is Video Out, and removing it prevents a signal from being broadcast by the TV into the cable in the first place, so it cannot cross-talk with the incoming signal. Cheaper SCART plugs can sometimes have the pins pushed inside the connector housing so as to remove it in a non-destructive manner (and thus allowing for its replacement in the future should the need arise by simply unscrewing the housing and pushing the pin back through its hole), though sometimes the pins are fixed in place on the inside by glue or rubber and can only be removed by forcefully twisting them off entirely. Generally though, for a standalone TV there is no need for video output on the TV end of the SCART plug, so in the majority of cases removing it completely should not be a problem (n.b. with the recent digital switchover in the UK many newer ("digital") TVs pass their Freeview signal back to DVD recorders/VCRs to allow you to record Freeview from the AV channel that the TV is connected to without the need for an additional set top box, so if you have Sky/Virgin you can watch Sky/Virgin on AV whilst recording the Freeview channel selected on the TV's built-in digital tuner at the same time; removing this pin 19 will prevent this functionality). Whichever way it is done, however, once it is the SCART is rendered incapable of transmitting a video signal from that end of the cable, so it would be wise to mark it as such for future reference.
Pin 8, the switch signal pin, carries a DC voltage from the source that indicates the type of video present.
Pin 16, the blanking signal pin, carries a signal from the source that indicates that the signal is either RGB or composite.
The original specification defined pin 16 as a high frequency (up to 3 MHz) signal that blanked the composite video. The RGB inputs were always active and the signal 'punches holes' in the composite video. This could be used to overlay subtitles from an external Teletext
decoder.
There is no switching signal to indicate S-Video. Some TVs can auto-detect the presence of the S-Video signal but more commonly the S-Video input needs to be manually selected.
SCART leads are available to buy in a wide range of stores in Europe
and in specialised stores in North America
.
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
-originated standard and associated 21-pin connector for connecting audio-visual (AV) equipment together. It is also known as (especially in France, where the term SCART is practically unknown), 21-pin EuroSCART (Sharp
Sharp Corporation
is a Japanese multinational corporation that designs and manufactures electronic products. Headquartered in Abeno-ku, Osaka, Japan, Sharp employs more than 55,580 people worldwide as of June 2011. The company was founded in September 1912 and takes its name from one of its founder's first...
's marketing term for an attempt to market the connector in the Asian region), Euroconector or EuroAV. In America, another name for SCART is EIA Multiport (an EIA interface).
In Europe, SCART is the most common method of connecting audio-visual equipment together, and has become a standard connector for such devices (even more so than the phono plug
RCA connector
An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals...
); it is far less common elsewhere in the world. Designed to carry analog standard-definition content, SCART is becoming obsolete with the introduction of new digital standards such as HDMI
HDMI
HDMI is a compact audio/video interface for transmitting uncompressed digital data. It is a digital alternative to consumer analog standards, such as radio frequency coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, or VGA...
, which can carry high-definition
High-definition video
High-definition video or HD video refers to any video system of higher resolution than standard-definition video, and most commonly involves display resolutions of 1,280×720 pixels or 1,920×1,080 pixels...
content and multichannel audio
Surround sound
Surround sound encompasses a range of techniques such as for enriching the sound reproduction quality of an audio source with audio channels reproduced via additional, discrete speakers. Surround sound is characterized by a listener location or sweet spot where the audio effects work best, and...
. Yet HDMI does build on some concepts originally developed for SCART; for example, HDMI-CEC is derived from SCART's AV.link
AV.link
AV.link, also known under the trade names nexTViewLink, SmartLink, Q-Link, EasyLink, etc. is a protocol to carry control information between audio-visual devices connected via the SCART connector....
.
The official standard for SCART is CENELEC document number EN 50049-1. SCART is sometimes referred to as the IEC 933-1 standard.
Origins
The SCART connector first appeared on television sets in 1977. It became compulsory on all new television sets sold in France starting from January 1980.Before SCART came, consumer TV sets did not offer a standardised way of putting in signals other than RF
RF connector
A coaxial RF connector is an electrical connector designed to work at radio frequencies in the multi-megahertz range.RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission...
antenna connectors, and even antenna connectors differed among countries. Assuming other connectors even existed, devices made by various companies could have different and incompatible standards. For example, a domestic VCR could output a composite video
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
signal through a German-originated DIN-style connector, an American-originated RCA connector
RCA connector
An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals...
, an SO239 connector, or a BNC connector
BNC connector
The BNC connector ' is a common type of RF connector used for coaxial cable. It is used with radio, television, and other radio-frequency electronic equipment, test instruments, video signals, and was once a popular computer network connector. BNC connectors are made to match the characteristic...
.
Usage
The SCART system was intended to simplify connecting audio-video equipment (including TVsTelevision
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
, VCRs, 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....
players and game consoles
Video game console
A video game console is an interactive entertainment computer or customized computer system that produces a video display signal which can be used with a display device to display a video game...
). To achieve this it gathered all of the analogue signal connections into a single cable with a unique connector that made incorrect connections nearly impossible.
The signals carried by SCART include both composite
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
and RGB (with composite synchronisation) video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
, stereo
STEREO
STEREO is a solar observation mission. Two nearly identical spacecraft were launched into orbits that cause them to respectively pull farther ahead of and fall gradually behind the Earth...
audio input/output and digital signalling. The standard was extended at the end of the 1980s to support the new S-Video
S-Video
Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...
signals. In addition, a TV can be awakened from standby mode or switched to video mode through a SCART connector.
Daisy chaining
Teletext
Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...
.
A VCR will typically have two SCART sockets, one connecting to the television set ("up", "primary" or "1"), and another one for the set-top box or other devices ("down", "secondary" or "2"). When idle or powered off, the VCR will forward the signals from the television set to the set-top decoder and send the processed result back to the television set. When a scrambled show is recorded, the VCR will drive the set-top box from its own tuner and send the unscrambled signals to the television set for viewing or simple recording control purposes. Alternatively, the VCR could use the signals from the television set, in which case it would be inadvisable to change channels on the television set during the recording.
The "down" socket can also be used to connect other devices, such as DVD players or game consoles. As long as all devices have at least one "up" and "down" socket, this allows for connecting a virtually unlimited number of devices to a single SCART socket on the TV set. While audio and video signals can travel both "up" to the TV set and "down" to devices farther away from the TV, this is not true for RGB (and non-standard YPBPR) signals, which can only travel towards the TV set.
"Up" and "down" are conventional.
Logically the TV set is the last device of the "up" chain-path (stream) and the first device in the "down" chain path (stream).
Physically the TV is under the device which sits on its top, hence the name set-top-box for the device. Moreover some sockets relative position may enforce the belief that the TV is physically the last in the down direction.
Logically, the TV set is on top and ends the "up" chain-path (stream), translating the electrical info in optic and audio.
From the same logical point of view the info stream, wherever it originates, may need processing such as decrypting (decoding, descrambling) or adding captioning/subtitles. In this case the info stream is sent logically "down" to dedicated function devices. From the last processing device the info stream is sent logically "up" to the TV set, through all the chain-path.
Another case is when the info stream is sent "down" and not expected to be sent back "up", for example when sent to a recorder.
Closing a loop on either "up" or "down" chain-path (stream) may not have useful effects and may create instability.
Direct connections
As the pins for Audio and (Composite) Video use the same pins on "up" and "down" connectors (and require a crosslinked cable), it is also possible to connect two devices directly to each other without paying attention to the type of the socket.However, this no longer works when S-Video signals are used. As straight links (RGB Red and Blue up) were re-purposed to carry chrominance information, the S-Video pinouts are different for "up" and "down" SCART connectors. Further, they are often not fully implemented.
Paying attention to the type of socket is essential when handling component RGB/YPBPR/S-video. Damage can be caused to devices incorrectly connected as follows:
- connecting SCART 1 ("up") from one device to SCART 1 ("up") of another device when both SCARTs are configured for RGB/YPBPR/S-video-up. Pins 7, 11 and 15 are outputs.
- connecting SCART 2 ("down") from one device to SCART 2 ("down") of another device when both SCARTs are configured for S-video-down. Pin 7 is an output.
- connecting SCART 1 ("up") from a device configured RGB/YPBPR, to SCART 2 ("down") of another device configured with S-video-down. Pin 7 is an output.
Damaging only pin 7 may result in yellow images, due to the missing blue. Likewise damaging pin 11 or 15 may result in purple or blue/green images, due to the missing green or red components (respectively). When using S-video, damaging pin 7 or 15 may result in black-white images due to the missing chroma component ("down" and "up" respectively). Similarly, damaging pins 7 and 15 (PB and PR) while leaving pin 11 (Y) undamaged may result in black-white images when using YPBPR. Damaging more than one of these pins may result in combined effects.
RGB overlays (fast switching)
SCART also enables a device to command the television set to very quickly switch between signals, in order to create overlays in the image. In order to implement captioning or subtitles, a SCART set-top box does not have to process and send back a complete new video signal, which would require full decoding and re-encoding of the colour information, a signal-degrading and costly process, especially given the presence of different standards in Europe. The box can instead ask the television set to stop displaying the normal signal and display a signal it generates internally for selected image areas, with pixelPixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
-level granularity. This can also be driven by the use of a "transparent" colour in a teletext page.
Status and aspect ratio (slow switching)
SCART allows a connected device to bring it in and out of standby mode or to switch it to the AV channel. A VCR or other playback device will optimally power on when a cassette is inserted, power on the television set (or switch it to video mode) and then start playing immediately if the cassette's write protection tab is absent. When turned off, the VCR will ask the television set to power off as well, which the set will do if it had been powered on by the VCR's request and if it remained in video mode all along. Only some TV sets will do this—most only implement automatic switching to and from the SCART input.The same signal can be used by a satellite receiver
Receiver (radio)
A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
or set top box to signal a VCR that it is supposed to start and stop recording ("pin 8 recording"). This configuration usually requires that the VCR be farther from the TV set than the source, so the signal usually travels "down".
SCART also supports automatic widescreen
Widescreen
Widescreen images are a variety of aspect ratios used in film, television and computer screens. In film, a widescreen film is any film image with a width-to-height aspect ratio greater than the standard 1.37:1 Academy aspect ratio provided by 35mm film....
switching. This is an extension of the functionality of a pin which previously only indicated to the TV set that an external signal should be displayed. Ideally, a widescreen source should offer three operating modes in order to deal with widescreen signals:
- Widescreen, for televisions that are widescreen or capable of otherwise dealing with widescreen images
- LetterboxLetterboxLetterboxing is the practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio. The resulting videographic image has mattes above and below it; these mattes are part of the image...
, which adds blank space (usually black) at the top and bottom of the image to give a 4:3 aspect ratio - Pan and scanPan and scanPan and scan is a method of adjusting widescreen film images so that they can be shown within the proportions of a standard definition 4:3 aspect ratio television screen, often cropping off the sides of the original widescreen image to focus on the composition's most important aspects...
, which crops the image to achieve a 4:3 aspect ratio; only the centre portion is displayed with the sides truncated (as if zoomed into).
In the first case, the widescreen pin allows to indicate the current signal format, which allows widescreen sets to adjust the image width, and widescreen-capable standard sets to compress the image vertically. In the second case, the widescreen SCART signal is never active and the signal source performs the adaptations itself so that the image has always a standard format as a result. In practice, some sources will assume that the television set is always capable of widescreen functionality and hence never perform the adaptations. Some source will not even issue the widescreen signal or maintain it at the same level all the time. Other sources might offer the option of truncating the sides, but not of letterboxing, which requires significantly more processing. Notably, the circuitry of the early widescreen MAC
Multiplexed Analogue Components
Multiplexed Analogue Components was a satellite television transmission standard, originally proposed for use on a Europe-wide terrestrial HDTV system, although it was never used terrestrially.- Technical overview :...
standard decoders (e.g. the Visiopass) could not letterbox. The limitations apply mostly to satellite television receivers, while DVD players can always at least letterbox and often zoom.
Data bus
The use of the data pins was not standardised in the original SCART specification, resulting in the use of several different protocols, both proprietary protocols and semi-proprietary protocols based on standards such as D²B.Some of the most creative usages appeared in analog satellite receivers. The function of decoding hybrid, time-compressed analog-digital MAC
Multiplexed Analogue Components
Multiplexed Analogue Components was a satellite television transmission standard, originally proposed for use on a Europe-wide terrestrial HDTV system, although it was never used terrestrially.- Technical overview :...
transmissions into RGB and analog audio was akin to making a digital receiver out of an analog one. The D²B pins (10 and 12) were used for communicating with satellite dish
Satellite dish
A satellite dish is a dish-shaped type of parabolic antenna designed to receive microwaves from communications satellites, which transmit data transmissions or broadcasts, such as satellite television.-Principle of operation:...
positioners and for driving magnetic polarisers
Polarizer
A polarizer is an optical filter that passes light of a specific polarization and blocks waves of other polarizations. It can convert a beam of light of undefined or mixed polarization into a beam with well-defined polarization. The common types of polarizers are linear polarizers and circular...
, before these became incorporated into LNB
Low-noise block converter
A low-noise block downconverter is the receiving device of a parabolic satellite dish antenna of the type commonly used for satellite TV reception...
s. The daisy-chaining features were used to connect both a Pay TV decoder and a dish positioner/polariser to a single Decoder socket on the receiver.
CENELEC EN 50157-1 introduced AV.link
AV.link
AV.link, also known under the trade names nexTViewLink, SmartLink, Q-Link, EasyLink, etc. is a protocol to carry control information between audio-visual devices connected via the SCART connector....
as a standardised protocol to carry advanced control information between devices. It is a single-wire serial data bus
Electrical bus
Electric bus is a bus powered by electric energy. "Electric bus" can also refer to:* Bus , used for connecting components of a computer or communication between computers* Busbars, thick conductors acting as nodes in electrical substations...
and allows carrying remote control information and to negotiate analogue signal types (e.g. RGB).
AV.link is also known as nexTViewLink or under different trade names such as SmartLink, Q-Link, EasyLink, etc. It appears as the Consumer Electronics Control channel in HDMI
HDMI
HDMI is a compact audio/video interface for transmitting uncompressed digital data. It is a digital alternative to consumer analog standards, such as radio frequency coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, or VGA...
.
Cordset types
| Type | Ring colour | Pins | Description | Symmetric | |
|---|---|---|---|---|---|
| U | Universal | black | 1–20, 21 | Fully wired cable. | no |
| V | Video only | white | 17–20, 21 | Only composite wires. | yes |
| C | Combined | grey | 1–4, 6, 17–20, 21 | Composite Video and Audio | yes |
| A | Audio only | yellow | 1–4, 6, 21 | Audio | yes |
| B | Bus | green | 10, 12, 21 | Only data connections | 1 |
1 depends on protocol used.
Disadvantages
- RGB connections are not bidirectional. Bidirectional S-Video was added in an extension, although few devices support this, so downstream connections are almost always composite.
- SCART is sometimes confusing for consumers. Some TV sets that have multiple SCART connectors have only one capable of receiving RGB and the other one capable of receiving S-video. Also, not all SCART cables make use of all the pins, often leaving out RGB signals. In many cases there is also no way to see which type of signal is currently displayed on the TV set. However, because of compatibility with set top boxes, at least one SCART socket must be full-featured, i.e. both issue and accept composite video, and accept RGB video. In recent years, non fully wired SCART cables have tended to disappear from the market, because modern devices systematically provide RGB signals, while composite-only, analog VCRs and pay-TV decoders could not.
- SCART cannot officially carry non-RGB (e.g. YPBPRYPbPr' is a color space used in video electronics, in particular in reference to component video cables. is the analog version of the YCBCR color space; the two are numerically equivalent, but YPBPR is designed for use in analog systems whereas YCBCR is intended for digital video. cables are also...
) component videoComponent videoComponent video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video information that is transmitted or stored as three separate signals...
signals, which are gaining ground as an improvement over S-Video in markets where SCART is not used. However, some manufacturers of set-top-boxes and DVD players are known to provide optional (menu-selectable), non-standard YPBPR output through the pins that are officially reserved for RGB colour components. - SCART connectors provide only limited locking, using detentDetentDetent is the term for a method, as well as the actual device, used to mechanically resist or arrest the rotation of a wheel, axle or spindle....
s, and are prone to falling off or getting loose, especially since the thick 21-wire cable is relatively heavy and often leaves the connector at a sideways angle. Loss of audio or video connection due to a loose SCART connector is relatively common. Depending on which end of the plug is loose, either a loss of audio (rectangular end) or a loss of video (triangular end) is observed. - The thickness and inflexibility of the cables, combined with the fact that they are connected to the plugs at an angle, can sometimes make it difficult to connect items of equipment, especially in confined spaces. Attempts at thinner cables are more susceptible to cross-talk, or are unable to support all communication modes. Ribbon cables may avoid mechanical tension of classic cables. Ribbon cables are perfectly suited to chain-connected stacked devices.
- The connector design requires the plug to be perfectly aligned over the socket before it can be inserted at all, whereas more recent connector designs are self-correcting if the plug is inserted at slightly the wrong angle.
- Cheap 10-pin SCART connectors can be very fragile and prone to breaking or losing pins, since they are big and hollow. 21-pin connectors are generally stronger.
Practical considerations
Nearly all DVDDVD
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....
players with SCART sockets output RGB video, which offers far superior picture quality to typical composite signals. However, many players do not have RGB output turned on by default but composite video
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
—this often has to be set manually in the player's setup menu or via switches on the back of the player.
Nintendo GameCube
The , officially abbreviated to NGC in Japan and GCN in other regions, is a sixth generation video game console released by Nintendo on September 15, 2001 in Japan, November 18, 2001 in North America, May 3, 2002 in Europe, and May 17, 2002 in Australia...
, Wii
Wii
The Wii is a home video game console released by Nintendo on November 19, 2006. As a seventh-generation console, the Wii primarily competes with Microsoft's Xbox 360 and Sony's PlayStation 3. Nintendo states that its console targets a broader demographic than that of the two others...
, Dreamcast, PlayStation, PlayStation 2
PlayStation 2
The PlayStation 2 is a sixth-generation video game console manufactured by Sony as part of the PlayStation series. Its development was announced in March 1999 and it was first released on March 4, 2000, in Japan...
, PlayStation 3
PlayStation 3
The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...
, Xbox
Xbox
The Xbox is a sixth-generation video game console manufactured by Microsoft. It was released on November 15, 2001 in North America, February 22, 2002 in Japan, and March 14, 2002 in Australia and Europe and is the predecessor to the Xbox 360. It was Microsoft's first foray into the gaming console...
and Xbox 360
Xbox 360
The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...
can output RGB
RGB color model
The RGB color model is an additive color model in which red, green, and blue light is added together in various ways to reproduce a broad array of colors...
, component video
Component video
Component video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video information that is transmitted or stored as three separate signals...
, S-Video
S-Video
Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...
, or composite video
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
. These consoles come with the standard composite video connector, but the manufacturers and third parties sell connectors for component video hookup and for RGB SCART hookup. Where the Nintendo GameCube and Xbox automatically switch to the proper mode, the PlayStation 2 must be told via a selection in the system menu whether it is to use YPBPR or RGB video. Also, some versions of legacy consoles such as Sega's Mega Drive (Genesis) and Nintendo's SNES
Super Nintendo Entertainment System
The Super Nintendo Entertainment System is a 16-bit video game console that was released by Nintendo in North America, Europe, Australasia , and South America between 1990 and 1993. In Japan and Southeast Asia, the system is called the , or SFC for short...
and Nintendo 64
Nintendo 64
The , often referred to as N64, was Nintendo′s third home video game console for the international market. Named for its 64-bit CPU, it was released in June 1996 in Japan, September 1996 in North America, March 1997 in Europe and Australia, September 1997 in France and December 1997 in Brazil...
(modified NTSC and early French SECAM versions only) are capable of outputting RGB signals.
† RGB is only available on PAL region
PAL region
The PAL region is a television publication territory which covers most of Asia, Africa, Australia, New Zealand, and most of Western Europe...
GameCube and Wii consoles, while S-Video is only available on NTSC consoles.
Many older home computers (Amstrad CPC
Amstrad CPC
The Amstrad CPC is a series of 8-bit home computers produced by Amstrad between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the Commodore 64 and the Sinclair ZX Spectrum, where it successfully established itself primarily in the United Kingdom,...
, later ZX Spectrum
ZX Spectrum
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd...
models, Commodore Amiga, Atari ST
Atari ST
The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...
, BBC Micro
BBC Micro
The BBC Microcomputer System, or BBC Micro, was a series of microcomputers and associated peripherals designed and built by Acorn Computers for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation...
and Acorn Archimedes
Acorn Archimedes
The Acorn Archimedes was Acorn Computers Ltd's first general purpose home computer to be based on their own ARM architecture.Using a RISC design with a 32-bit CPU, at its launch in June 1987, the Archimedes was stated as running at 4 MIPS, with a claim of 18 MIPS during tests.The name is commonly...
, etc.) output RGB with composite sync suitable for SCART use, but most used varying non-standard DIN plugs. Standard-resolution arcade monitors use RGB signals with a composite sync, which is SCART-compatible.
Maximum SCART cable length is estimated to be about 10 to 15 metres without amplification.
Due to the relatively high voltage used in SCART, "hot plugging" (connecting or disconnecting devices while they are on) is not recommended. Although there is no risk of personal injury, there is the possibility of damaging electronics within the devices if the connector is inserted improperly.
Quality differences exist in SCART cables. While a proper SCART cable uses miniature coax cables for the video signals, cheap SCART cables often use plain wires for all signals, resulting in a loss of image quality and greatly reducing the maximum cable length. A common problem is that a TV outputs a composite video signal from its internal tuner, and this is induced or cross-talked
Crosstalk (electronics)
In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel...
onto an incoming video signal due to inadequate or non-existent screening on a cheap SCART cable; the result is ghostly images or shimmering superimposed on the incoming signal. To non-destructively verify if a SCART cable uses coax cables, one can unscrew the strain relief at the SCART connector and fold open the plastic shell.
Using higher-quality cables such as those with ribbon cords that have properly shielded coax cables inside might help in reducing a 'ghosting' effect, but it does not always completely eliminate it due to various factors. A more permanent method is to remove pin 19 from the SCART plug that is put into the TV. Pin 19 is Video Out, and removing it prevents a signal from being broadcast by the TV into the cable in the first place, so it cannot cross-talk with the incoming signal. Cheaper SCART plugs can sometimes have the pins pushed inside the connector housing so as to remove it in a non-destructive manner (and thus allowing for its replacement in the future should the need arise by simply unscrewing the housing and pushing the pin back through its hole), though sometimes the pins are fixed in place on the inside by glue or rubber and can only be removed by forcefully twisting them off entirely. Generally though, for a standalone TV there is no need for video output on the TV end of the SCART plug, so in the majority of cases removing it completely should not be a problem (n.b. with the recent digital switchover in the UK many newer ("digital") TVs pass their Freeview signal back to DVD recorders/VCRs to allow you to record Freeview from the AV channel that the TV is connected to without the need for an additional set top box, so if you have Sky/Virgin you can watch Sky/Virgin on AV whilst recording the Freeview channel selected on the TV's built-in digital tuner at the same time; removing this pin 19 will prevent this functionality). Whichever way it is done, however, once it is the SCART is rendered incapable of transmitting a video signal from that end of the cable, so it would be wise to mark it as such for future reference.
Blanking and switching
Two pins provide switching signals.Pin 8, the switch signal pin, carries a DC voltage from the source that indicates the type of video present.
- 0 V–2 V means no signal, or internal bypass
- 4.5 V–7 V (nominal 6 V) means a widescreen (16:9) signal
- 9.5 V–12 V (nominal 12 V) means a normal (4:3) signal
Pin 16, the blanking signal pin, carries a signal from the source that indicates that the signal is either RGB or composite.
- 0 V–0.4 V means composite.
- 1 V–3 V (nominal 1 V) means RGB only.
The original specification defined pin 16 as a high frequency (up to 3 MHz) signal that blanked the composite video. The RGB inputs were always active and the signal 'punches holes' in the composite video. This could be used to overlay subtitles from an external Teletext
Teletext
Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...
decoder.
- 0 V–0.4 V means composite with a transparent RGB overlay.
- 1 V–3 V (nominal 1 V) RGB only.
There is no switching signal to indicate S-Video. Some TVs can auto-detect the presence of the S-Video signal but more commonly the S-Video input needs to be manually selected.
Cables
The cables for connecting equipment together have a male plug at each end. Some of the wires such as ground, data, switching and RGB connect to the identical pin number at each end. Others such as audio and video are swapped so that an output signal at one end of the cable connects to an input signal at the other end. The complete list of wires that are swapped is: pins 1 and 2, pins 3 and 6, pins 17 and 18, pins 19 and 20.SCART leads are available to buy in a wide range of stores in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and in specialised stores in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
.
See also
- DisplayPortDisplayPortDisplayPort is a digital display interface standard produced by the Video Electronics Standards Association . The specification defines a royalty-free digital interconnect for audio and video. The interface is primarily used to connect a video source to a display device such as a computer monitor...
- HDMIHDMIHDMI is a compact audio/video interface for transmitting uncompressed digital data. It is a digital alternative to consumer analog standards, such as radio frequency coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, or VGA...
- RCA connectorRCA connectorAn RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals...
- RF connectorRF connectorA coaxial RF connector is an electrical connector designed to work at radio frequencies in the multi-megahertz range.RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission...
- EIA interface
- List of display interfaces
External links
- Paul Gardiner, Peter Barnett, Preliminary Investigation of a SCART Lead Benchmarking Scheme
- SCART connector pinout and cables schemes
- SCART — hardwarebook.info
- RGB/VGA and SCART