S-video vs. Component Video
Which is Better?
S-video and component video inputs are common on a wide variety of video devices, and that leads to the question: when one has a choice, which is the better connection to use?
To cut to the chase -- after which, we'll provide a bit of explanation -- component video (not to be confused with "composite video," usually represented by a single yellow-coloured RCA jack) is the better of these two video signal formats, because it provides better colour definition and is compatible with a wide variety of resolutions and with progressive scan signals.
To understand why that's so, it's helpful to know just what s-video and component video are.
S-video is a format first seen in the consumer market on Super-VHS, or "S-VHS," video tape recorders. Prior to the arrival of s-video, practically the only baseband video signal type supported on consumer equipment was composite video, in which all picture information including colour, brightness, and horizontal and vertical synchronization, is encoded into a single signal, carried on a single coaxial cable, usually terminated with an RCA connector. Composite video was a natural choice for these applications, because standard VHS recordings are recorded as composite video, and because composite video is the form in which standard-definition NTSC video signals have been recorded since the arrival of colour TV in the U.S. Composite video never handled colour very well, being a standard that was cobbled together for the sole purpose of saving early black-and-white TV sets from being made obsolete by colour broadcasts.
The S-VHS VCR introduced s-video, known in the professional world as "Y/C", to the consumer market. In s-video, instead of colour and brightness being carried on the same wire, there are two cables (usually in a bundle so compact that it's easy not to notice until you look at the connector) involved. One cable carries luminance (brightness, or the "Y" part of Y/C) information, along with sync pulses, and the other carries chrominance -– the colour information. Separating these two out from one another improves resolution and colour definition.
But s-video, like composite video, was created for standard-definition television in the basic NTSC broadcast format. Both composite and s-video support only interlaced, standard-definition video, now generally referred to as 480i. Progressive scan, and higher resolutions, are not available on composite or s-video connections.
Component video is a colour-difference video format which carries the splitting-out of information one step further. Instead of two cables like s-video, component video uses three. These are Y (Luminance again, along with the sync pulses), Pb (Blue minus Luminance), and Pr (Red minus Luminance). Color rendering is a step better than s-video, but what's more significant is that Y/Pb/Pr component video will also support higher resolutions and progressive scan, so if your video is running at 480p, 720p, 1080i, 1080p, (or, for that matter, any other oddball resolution which your source and display devices both support), you can make use of the full capabilities of your equipment.