Composite video is the most common type of video interface for sending or receiving an analog video signal to or from a television set. A composite video interface might connect a VHS tape player, DVD player or game console to a television.
Composite video is a yellow, female RCA jack, normally found next to two audio jacks, one red, the other white. The three jacks together provide an interface for audiovisual connections. The red RCA jack connects the right channel of a stereo system, while the white RCA jack connects the left. The yellow composite video jack rounds out the set.
A video stream is composed of a Y signal for luminescence or black and white values and a C signal for chrominance or color. The Y signal provides brightness and contrast, allowing for deep rich blacks and startling bright whites. The quality of this signal is especially evident in low-lit scenes where a degraded signal will translate to "faded" blacks and muted whites, making it difficult to differentiate scenery or action. The color signal —- or RGB for red, green and blue -- carries the information needed to create changing hues. A degraded C signal can result in coloration that is not true to its source.
Composite video is so named because the Y/C signals are compressed and channeled through a single wire to be separated by a "comb filter" inside the television set. Though composite video was the standard for many years, the very process causes some degradation of signal integrity. This wasn't a problem in the past as television resolution and audiovisual equipment in general was inferior to today's standards. However, with the advent of high-definition television and DVD, the drawbacks of composite video have become evident on screen.
Limitations of composite video led to S-Video, a mini-DIN interface that carries the Y/C signals separately, each getting their own wire wrapped inside a single sheath to appear as a single cable. S-Video is also analog and still requires audio cables.
More recently, S-Video has been superseded by component video, which isolates not only the Y signal on its own cable, but the red and blue signals as well, while green values are inferred from reading the other data streams. Component video requires three cables plus audio cables, for a total of five cables. The latest enhancement in audiovisual interfaces is High-Definition Multimedia Interface (HDMI), a true digital interface that combines video and audio into a single cable while preserving perfect integrity. This all-digital standard is the most desirable interface currently available.
