The Digital Home Company - Component Video

Component video is a type of analog video information that is transmitted or stored as two or more separate signals. Component video can be contrasted with composite video (such as NTSC or PAL) in which all the video information is combined into a single signal such as a TV broadcast. Currently, component video connections are gradually being superseded by the higher quality digital DVI and HDMI interface.

Analog video signals (also called components) must provide red, green and blue signals to create a television image. The simplest type, RGB, consists of the three discrete red, green and blue signals sent down three coaxial cables. There are a number of schemes which vary according to how synchronization is handled. If a synchronisation signal is sent on the green channel, it is called sync-on-green. Some schemes use a separate sync channel, for instance the European SCART connection scheme in which the video signal occupies four (R,G,B + sync) of the 21 pins in the interface. SVGA, another RGB scheme, is used worldwide for computer monitors (this is sometimes known as RGBHV, as the horizontal and vertical synchronisation pulses are sent on separate lines).

An alternative type of componentization does not use R,G,B components but rather a colorless component, termed luminance combined with one or more color-carrying components, termed chrominance, that give only color information. Mulitiple chrominance channels allow for more precision and speed in mapping the RGB colour space. This componentization scheme is a linear transformation of the sRGB color space. This type of signal is usually what is intended when people talk of component video today. Variants of this format include YUV, YCbCr, YPbPr and YIQ commonly used in video systems.

In component video systems, additional synchronization signals may need to be sent along with the images. The synchronization signals are commonly transmitted on one or two separate wires, or embedded in the blanking period of one or all of the components. In computing, the common standard is for two extra wires to carry the horizontal and vertical components ('separate syncs'), whereas in video applications it is more usual to embed the sync signal in the Y component ('sync on luminance').

S-Video is another type of component video signal, because the luminance and chrominance signals are transmitted on separate wires. This connection type, however, cannot produce high definition (pictures with more than 480 interlaced lines of video for NTSC or more than 576 lines of interlaced video for PAL).

Component video is capable of producing signals such as 480p, 720p, 1080i and 1080p, but digital connections such as DVI (video only) and HDMI (which can also include up to 8 channels of audio) give better results at the higher resolutions (up to 1080p). HDMI also includes both a video and audio signal in a single cable.
Reference: http://www.wikipedia.com