Video and Broadcasting

Composite video is the standard that can connect almost all consumer video equipment - television sets, DVD players, VCRs and camcorders.

Normally it is transmitted over basic composite video cables with male RCA plugs on each end. Sometimes you will see these as dual RCA cables, which are used for stereo audio cables, and also a triple RCA cables for combined composite video and stereo audio cables.

Composite video combines the three basic elements of a video picture (color, brightness, and synchronization data) into a single combined ("composite") signal.

S-Video, also called Y/C, uses two separate video signals. The luminance (Y) is the black & white portion, providing brightness information. The chrominance, or chroma (C) is the color portion, providing hue and saturation information.

Essentially, and S-video signal is a composite signal that has been divided into two. This video signal, transmitted with color and brightness on two separate channels, makes for a sharper picture image, with less granularity, on the receiving device.

S-Video is carried on cables that end in 4-pin Mini-DIN connectors. Other types of cables, such as the Apple ADB cable, also uses this same connector, although the type of wire used is different.

Since digitized granularity looks worse than analog granularity, choose S-Video over composite video whenever this is an option. You will also experience less "dropout" with S-Video than with composite video.

TV Cable signals are carried as a single, composite-type 75-Ohm analog signal. Usually, RG59 or RG6 coaxial wire is used. The RG59 cable is good for up to 750 feet without boosting, and RG6 is good for up to 1500 feet without boosting. The maximum signal strength allowed by the FCC is 15.5dBmV. Add attenuators when the signal is too high, and tilt compensators for long-distance runs.

Although Component Video is sometimes refered to as RGB video, RGB is not actually a video standard, but rather a standard for computer monitors. It requires a four conductor cable for connecting a monitor to a CPU. In concept, it is similar to S-Video. Three of the conductors carry color information for the red, green and blue components of the image, while the fourth, called the "sync" or synchronization line, carries timing information to be used concurrently with the color information.

Because RBG separates the video signals based on color information and not luminance/chroma, it is possible to create an RGB to VGA cable without electronic conversions.

Component video is a newer format of video signal that takes the advancement from composite (1-signal) to S-Video (2-signals) one step further. It has separated luma (brightness) and chroma (color), but the chroma is also separated into two signals, red and blue. The result is a triple-headed RCA cable and an image cleaner than composite with less color bleeding that S-Video. Although common on newer DVD players, high-end HDTV's, and relatively modern CRT televisions, component video is very rare on older TV sets and VCR's.

It is important to remember that with component video, the triple- headed cables are often colored red, green, and blue, but they do not carry color signals. Generally, these cables are known as YUV, Y for luma and UV for the two chromas. This is the reason that it is not possible to go directly from a computer monitor to a component source, and instead need a VGA-Component Adaptor.

NTSC

NTSC stands for National Television Standards Committee. It is the video transmission standard for North and Central America, including Mexico and Canada, and Japan. Its technical format is 525 lines per frame with roughly 30 fps (frames per second) refresh rate. It is pretty much synonymous with composite video when talking about a video signal, but is not necessarily equivalent to the output from a video capture card that may claim to be NTSC-legal.

PAL (Phase Alteration Line) is the European counterpart to the NTSC standard. It has a higher vertical resolution (625 lines per frame) but a lower refresh rate (25 frames per second) that can cause flickering. It is the standard for the UK, Western Europe, the Middle East, and parts of Africa and South America.

SECAM (Systeme Electronic Pour Couleur Avec Memoire) is very similar to PAL. It specifies the same number of scan lines and frames per second, but differs in that chrominance (color) is FM modulated. It is the broadcast standard for France, Russia, and parts of Africa and Eastern Europe.