What Is S-video?

By Author: Ronald Hall
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S-Video or Separate Video (also referred to as Y/S and erroneously as 'super video') is an analog video signal that transmits video data in two separate and distinct signals - one for color and the other for brightness. This procedure is a departure from the composite video concept where the entire set of information is transferred as a composite (all in one) package. S-Video works in 576i and 480i resolution.
Basic S-Video Overview
In S-Video, brightness (luminance) and color (modulated chrominance) subcarrier information is transmitted along separate synchronized signal-ground pairs.
In composite videos, eliminating the crosstalk between higher frequency brightness component and color subcarrier is accomplished through luminous signals subjected to low pass filtering. With S-Video, the two signals are completely separated. By doing so, the need for damaging low pass filtering is essentially eliminated. This process also increases the bandwidth for the luminous data and substantially reduces problems associated with color crosstalk. The infamous dot crawl (cross-luma) issue is also completely eliminated. ...
... Essentially, as S-Video leaves more data from the original video signal undisturbed, the viewers can enjoy a better image quality from their monitors than what is offered by conventional composite video.
Considering S-Video's basic technique of separating the video and color components, it is sometimes viewed as a different type of the component video signal. However, the major difference between S-Video and higher component video format is that in S-Video, the color information is sent as a separate signal altogether. This would mean that the colors have to be encoded, which further implies that the devices in the implementation of this process not only need to be compatible with S-Video, but also color encoding compliant.
Connectors Used with S-Video
For S-Video signals, the common connectors required are the 4-pin mini-DIN connectors using a termination impedance of 75 ohm. Without this impedance requirement, these cables are similar to the now replaced ADB (Apple Desktop Bus) and could be used in the event the proper cable is unavailable. However, in such cases, the picture quality will be somewhat degraded, and if used for longer periods, the incompatible resistance factor may ultimately do harm to the CRT.
To an extent, S-Video signals can also be transmitted through SCART connectors. However, keep in mind that as S-Video compatibility was not part of the original SCART standard. Remember, not all SCART compatible devices may be able to support S-Video signals. In such cases, if attempts are made to connect S-Video signals utilizing a SCART connector, it may result in a black & white image as only the luminance portion will be available for image decoding - devoid of color
Across the World
S-Video is widely used in Canada, US and Japan, where most of the DVD players, TVs, game consoles and video tape recorders are S-Video compatible. Given the ease of exchange between S-Video to composite, converter adapters are widely available and are useful in connecting S-Video out to otherwise non-compatible devices. In such cases, a separate audio connection may be required because S-Video does not carry sound.