S-Video
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S-Video, also known as Y/C and (incorrectly) SVHS, is an analog video signal. S-Video will appear better than composite video since the TV does not have to decode the brightness and color information that are found together on composite video.
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Method
The luminance (Y) signal and modulated chrominance (C) subcarrier information are carried on separate synchronized signal/ground pairs.
In composite video, the luminance signal is low-pass filtered to prevent crosstalk between high-frequency luminance information and the color subcarrier. S-Video, however, separates the two, so low-pass filtering is not necessary. This increases bandwidth for the luminance information, and also subdues the color crosstalk problem.
The luminance performance of S-Video is noticeably better than composite video; the chrominance performance with reduced crosstalk also shows noticeable improvement.
S-Video signals tend to degrade considerably when transmitted across more than 5 meters of cable with some cheaper S-Video cables.
Connector
SVideoConnector.jpg
Today, S-Video signals are generally connected using 4-pin mini-DIN connectors using a 75 ohm termination impedance. The pins in the connectors can bend easily but this is usually not a problem when properly inserting it to the s-video receptacle. If a pin is bent the result could be loss of color, corruption of the signal, or complete loss of the signal.
Before the mini-DIN plug became standard, S-Video signals were often carried through different types of plugs. For example, the Commodore 64 home computer of the 1980s, one of the first widely available devices to feature S-Video output, used an 8-pin standard size DIN plug on the computer end and a pair of RCA plugs on the monitor end. The S-Video connector is the most common video-out connector on laptop computers.
Today, S-Video signals can be transferred through SCART connections as well. However the device that has the SCART connector must support S-Video as it is not part of the original SCART standard. For instance, a VCR that has a SCART connector may not support S-Video, so if you try to connect an S-Video signal through a SCART connector you will get a black and white signal.
Usage
S-Video is commonly used on consumer TVs, DVD players, VTRs, and modern game consoles. Many computer video cards also have an S-Video output.
See also
References
- This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.