S-Video Cables

S-Video ("Separated Video"), also known as Y/C and (incorrectly) S-VHS, is an analog video signal. S-Video will appear better than composite video since the television does not have to split the brightness and color information that are found together on composite video. more...

The main advantages of separating these two signals are for better bandwidth of luminance and more effective work of chroma decoder, not to mention reduction of dot crawl.

Method

The luminance (Y) signal and modulated chrominance (C) subcarrier information are carried on separate synchronized signal/ground pairs. Because of this, S-Video is also considered a component signal.

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.

Some retailers (e.g. Radio Shack) offer S-video-to-composite (or vice versa) adaptors for signal conversion albeit nearly every device with an S-video output also has a composite output.

Connector

Today, S-Video signals are generally connected using 4-pin mini-DIN connectors using a 75 ohm termination impedance. However, 7-pin mini-DIN connectors are also common. 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, however many devices with s-video outputs also have composite outputs.

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. To get color on devices that does not support S-Video, you can try to join pin 15 and 20 in the SCART-connector as described here:

The 4-pin mini-DIN plug is identical to the one used for the now-obsolete Apple Desktop Bus. ADB cables can be used if no other cable is available, but picture quality may not be as good, and there may be a risk of damaging unshielded cathode ray tubes.

Read more at Wikipedia.org