S-video is one of a number of methods of separating a video signal into different components for transmission from a video cassette recorder or playback machine to a television set or video monitor. The technology was introduced to the market by JVC in 1987 as “separate video,” which was quickly shortened to "s-video." S-video cables are the cables that connect two devices that are equipped with s-video capability to transfer the signal from one to another.
With the advent of videocassette recorders and playback machines in the general consumer market in the late 1970s, one of the main points of competition among different manufacturers was the quality of the signal delivered to the television. The first VCRs were equipped with coaxial connectors and coaxial cable was used to transmit the video and audio signals to the television. S-video was one of a number of enhancements in bringing the signal from the video cassette player to the television, and separates the video signal into luma, or luminescence, and chroma, or color.
S-video cables carry four or more wires wrapped together in an insulated sleeve, with S-video connectors at either end. The most common S-video connector has four pins – one for the chroma signal, one for the luma, and two ground wires, one for each signal. The male connector has protruding pins and the female has corresponding slots. There are some S-video connectors with more than four pins, and S-video cables to match, but they are not very common.
S-video did not become very popular in the years after it was developed and introduced because the technology was available on only a small percentage of all televisions sold. Then, in the 1990s, as more sets were equipped with S-video, technology passed it by with the digital revolution.
S-video is an analog technology, and so S-video cables are not capable of carrying modern digital and high definition (HD) signals. A more significant drawback of S-video cables, though, is that they carry only the video components of a movie or television program – there's no provision for audio, either in the S-video technology or in S-video cables. Thus, a separate cable is required tor the audio signal, a major drawback in a consumer environment in which the emphasis is on simplicity and ease of operation.
S-video connectors and S-video cables will continue to have a presence in the marketplace, however, because as long as there are television sets capable only of displaying an analog video signal, there'll be a need for technologies like S-video to transmit the signal from the playback device to the television set or monitor.