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| * The SCART connects are non-locking 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. Also, cheap scart connectors can be very fragile and prone to breaking, losing pins, etc., since they are big and hollow. | * The SCART connects are non-locking 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. Also, cheap scart connectors can be very fragile and prone to breaking, losing pins, etc., since they are big and hollow. | ||
| * Maximum SCART cable length is estimated to about 10 to 15 meters without relay. | * Maximum SCART cable length is estimated to about 10 to 15 meters without relay. | ||
| * Quality differences exist in SCART cables. While a proper SCART cable would use miniature ] 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. (To non-destructively verify if a SCART cable uses ] cables, unscrew the ] at the SCART connector and fold open the plastic shell.) | * Quality differences exist in SCART cables. While a proper SCART cable would use miniature ] 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. (To non-destructively verify if a SCART cable uses ] cables, unscrew the ] at the SCART connector and fold open the plastic shell.) Also talking of quality, gold-plated scart connectors (which don't corrode and deliver a cleaner signal) always cost more than the cheap silver ones. | ||
| ==Pinout== | ==Pinout== | ||
Revision as of 22:41, 4 September 2005
SCART (from Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs) is a French-originated standard and associated 21-pin connector for connecting audio and video equipment to television sets. Also called Péritel (especially in France, where the SCART word is not normally used) and Euroconnector. SCART makes it easy to connect VCRs, DVD players, set-top boxes (Pay TV, analog or digital cable, terrestrial digital TV), home computers, gaming systems and other equipment to television sets with optimal quality.
Motivations and applications for SCART
Before SCART came, consumer TV sets did not offer a standardized way of inputting signals other than RF antenna ones, and even antenna connectors differed between countries. Assuming other connectors even existed, devices made by different companies could have different and incompatible standards. For example, a VHS VCR could output a composite video signal through a German-originated DIN-style connector or through an American-originated RCA connector.
SCART attempts to make connecting video devices together much simpler, by providing one plug that contains all the necessary signals (refer to the Pinout below for details), 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 you cannot insert it 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 pretty high, around 1V, so the signals are effectively immune to noise.
SCART is bidirectional 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 to have "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 2 SCART sockets, one connecting to the television set, and another one for the set-top box. 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 unadvisable to change channels on the television set during the recording.
The standard was extended at the end of the 1980s to support the new S-Video signals.
Drawbacks
- 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 carry other non-RGB type (eg. YPbPr) component video signals, which are gaining ground as an improvement over S-Video in markets where SCART is not used.
- SCART is not designed to transmit digital video or audio signals. The new (digital) audio+video HDMI connector is often referred to as 'Digital SCART'. From this it appears that there will never be a second generation analog SCART to address the above limitations.
- SCART is limited to two audio channels - meaning it cannot deliver true surround sound. However, transmitting a surround signal to a television set is of dubious interest.
The Nintendo GameCube, Sony PlayStation 2 and the Microsoft Xbox, can output RGB, Y-Cr-Cb, 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 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 component video.
For professional use, SCART has a few physical drawbacks:
- The SCART connects are non-locking 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. Also, cheap scart connectors can be very fragile and prone to breaking, losing pins, etc., since they are big and hollow.
- Maximum SCART cable length is estimated to about 10 to 15 meters without relay.
- Quality differences exist in SCART cables. While a proper SCART cable would use 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. (To non-destructively verify if a SCART cable uses coax cables, unscrew the strain relief at the SCART connector and fold open the plastic shell.) Also talking of quality, gold-plated scart connectors (which don't corrode and deliver a cleaner signal) always cost more than the cheap silver ones.
Pinout
Extensions to the original standard are in italics.
+------------------------------------------+ | 1 3 5 7 9 11 13 15 17 19 | 21 | \ | 2 4 6 8 10 12 14 16 18 20 \ +--------------------------------------------+
- Audio output, right
- Audio input, right
- Audio output, left
- Audio ground
- Blue ground
- Audio input left
- Blue
- Function switching (see below)
- Green ground
- D²B input
- Green
- D²B output
- Red/Chroma (C) ground
- D²B ground
- Red/Chroma
- Vertical blank (VBL)
- Composite video ground/Composite sync ground/Luminance (Y) ground
- VBL ground
- Composite video output/Composite sync output/Luminance (Y) output
- Composite video input/Composite sync input/Luminance (Y) input
- Common ground (metal shield)
Pin 8, the function-switching pin, carries a signal from the source that indicates the type of video present.
- 0V means no signal, or internal bypass
- +6V means a widescreen (16:9) signal
- +12V means a normal (4:3) signal
D²B (Digital Data Bus) is an IEC standard for a serial communication bus. It is a multi-master bus for home automation, and was originally developed by Philips in the 1970s.
Speculations about the intentions of the creators of SCART
The original purpose of SCART, according to some, was to prevent foreign television imports. Previously France had legislation which prevented all imported televisions, if they didn't support the old French 819 line monochrome system. One could understand that this effectively stopped any foreign televisions being imported, but when the 819 line system disappeared (its VHF frequency band was given to Canal Plus, the first French Pay TV network, at the beginning of the eighties) this was no longer a valid reason for banning imports. Therefore they introduced the SCART socket to try to maintain their private television market , the newly passed legislation requiring every TV sold in France since 1980 to have a SCART socket. This was of course much less of a deterrent, as it was much easier for manufacturers to add a SCART socket to their televisions than to produce dual-standard sets, and the SCART was actually useful elsewhere, with the development of home video recorders and especially of video games and home computers, which could be very easily connected to TV sets, giving the best possible image quality.
Another alleged reason was Minitel. Early prototypes did not have their own display; instead, they used the TV as their display, similar to games consoles. An RF interface would have provided lesser quality text. Originally, there were supposed to be many models of Minitel. In the end, only one major model shipped, and had a built-in small monochrome CRT.