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Which has better quality when transferring video: S-Video or composite?
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The short answer: Component

Explanation of all:

1. S-Video
(Separated-Video)

S-Video in

S-video cable differs from composite in that it carries the brightness (luminance, or Y) and color (chrominance, or C) signals on separate lines within the same cable. You can find S-video connections on S-VHS and Hi8 camcorders and VCRs, on better laserdisc players, on satellite receivers, and on better TV sets.

The bandwidth of S-video is the same as that of composite video. The real benefit of an S-video connection is that it can reduce dot crawl and hanging dots-crawling edges that appear on the vertical and horizontal edges (respectively) of some colored objects in the picture.

Note that we said it can reduce these effects, not that it will. The fact is, the Y and C signals are always split somewhere in the video chain, even if you use a 1965 color TV with an old rabbit-ears antenna. Every TV has a Y/C separator built in, but using the S-video connection bypasses the TV's Y/C separator.

The way S-Video works is that it basically separates the color information (Chrominance) from the brightness (Luminance). By doing this, it reduces things like color bleeding and dot crawl and greatly increases the general clarity and sharpness of the picture. The reason that this is so is that televisions are designed to display separate Luminance (Y) and Chrominance (C) signals.

2. Component (not composite) Video
[aka Analog Component Video; Y - Pb - Pr; red-green-blue]:

COMPONENT video in

Uses a three jack cluster of wires with the ends color coded green, blue, and red. (does not include audio cable).

Y-Pb-Pr, or what we nowadays refer to as component video or color difference video, was invented to simplify video electronics and reduce the overall bandwidth requirements for transmitting video compared with RGB. In practice it provides one luminance signal with full horizontal resolution and two color signals with reduced horizontal resolution.

Y = Luminance, Pb = Chrominance 1, Pr = Chrominance 2
From your DVD player or HDTV set top box to your TV, it is analog, thus its full name "analog component video".

Also referred to as Y, R-Y, B-Y or color difference video. Some DVD players label the green, blue, and red jacks Y, Cb, Cr .

3. RF Cable

In general, avoid RF cable because it can seriously degrade sound and picture quality. No matter where you live, stray RF signals of all sorts - TV, FM radio, fluorescent lights, and others - bombard your video cables. These signals interact with the RF video carried in the cable. RF video occupies very high (VHF) and ultra-high (UHF) frequencies, which start in the 50-megahertz range and go up from there. All but extremely high-frequency radio waves can interact with RF video signals. This interaction can produce ghosting, and stripe and herringbone interference patterns. Also, RF video signals carry at most 330 lines of horizontal resolution, so you lose the high resolution available from laserdisc players and S-VHS VCRs.

4. Composite Video
[RCA or BNC] (aka "yellow-plug" video)

composite video in

The old "AV" standard connector. The common RCA connector is color-coded Yellow for Composite video.

The term "yellow-plug video" is recommended to help cut down on confusion between "composite" and "component" (which sound alike).

Composite baseband video suffers from RF interference to a lesser degree than RF video. At baseband video's typical maximum frequency of about 5 megahertz, only low-frequency radio waves can interfere with it. Still, this interference can cause problems similar to those you experience with RF video cables.  Many video cables - even expensive high-end models - suffer from reduced bandwidth. This reduced bandwidth diminishes the high frequencies in the video signal, and robs you of the detail in your picture.

Unlike the inputs and outputs found on audio equipment, the characteristics of composite-video inputs and outputs are standardized. They all have an impedance (or resistance to the alternating current that makes up video signals) of 75 ohms. Your video cable should also have a 75-ohm impedance. Some cable manufacturers ignore this specification, though, using audio-grade cable and connectors instead of components designed for video. The result is that the signal can be reflected back and forth in the cable. When the reflected signal is mixed with the original signal, it cancels some video frequencies, so you can lose picture detail with poor-quality cables.

Summary

Quality

Cable and Connector

Connection Description

Best
Component - The video signal is split into three signals, two color and one black and white, giving you the best picture. Use component video to take advantage of the superior picture found in such signal sources as HDTV and progressive DVD.
Better S-Video - The video signal is split into two signals, giving you an even better quality picture. For example, text displayed on-screen using this connection is noticeably sharper than composite or coaxial (RF).
Good Composite ("yellow plug") - The video signal is carried through a single "pin". This connection type is the one that is most commonly found on video devices (as of 2004/2005).
Basic Coaxial (RF) - The video and audio signals are both carried in one cable. Used for antenna and cable signals.

(The other three connection types only handle video, requiring separate connections for sound.)

Last update: 08:32 AM Monday, January 1, 2007

 



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