SCART is a French-originated standard and associated 21-pin connector for connecting audio-visual equipment together. It is also known as Péritel (especially in France, where the SCART word is not normally used), 21-pin EuroSCART and Euroconnector.
SCART makes it easy to connect AV equipment (including TVs, VCRs, DVD players and game consoles). In essence, it gathers together various common analog signal types into a single connector. Previously, each of these would have had their own socket, requiring numerous separate connections. The signals carried by SCART include both composite and RGB video, and stereo audio input/output.
In Europe, SCART is the most common method of connecting audio-visual equipment together, and has become the standard connector for such devices. It is far less common elsewhere in the world.
SCART attempts to make connecting video devices together much simpler, by providing one plug that contains all the necessary signals and is standard across different manufacturers.
SCART makes connecting such devices very simple, because one cable can connect any two SCART-compatible devices, and the connector is designed so that it cannot be inserted incorrectly. Devices with multiple SCART connectors can pass the signals unchanged when not active, which allows daisy chaining of multiple signal sources into a single TV socket. The voltage levels are quite high, around 1 V, so the signals have good noise immunity.
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.
SCART allows a connected device to power on and power off a television set, more precisely: to bring it in and out of standby mode, in the same way as a remote control would do. A VCR 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.
SCART cannot carry both S-Video and RGB signals at the same time. It is, however, possible to output S-Video and RGB alternately, (for example, from an S-VHS + DVD combo player), and the TV set will adapt automatically if it understands SCART's S-Video extension.
Many DVD players sold in Europe offer the ability to output either RGB or S-Video, which is either selected in the DVD player's set-up menu or by a switch on the back of the system.
SCART cannot officially carry non-RGB (e.g., YPbPr) component video 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 color components.
SCART is not designed to transmit digital video or audio signals.
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 or flat cables are more susceptible to cross-talk, or are unable to support all communication modes.
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.
SCART can sometimes be confusing for consumers. Most 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 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. The picure quality of the different signals mentioned here can be ranked as follows:
Nearly all DVD 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 - this often has to be set manually in the player's setup menu or via switches on the back of the player.
Maximum SCART cable length is estimated to be about 10 to 15 meters without relay.
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.
