As its name suggests, S-Video or Separate-Video, refers to an interface that only delivers the video signals without the audio counterpart. Considering all the hype around the HDMI interface, you might think that S-Video is obsolete. However, it is necessary to mention numerous devices out there (gaming consoles and DVD players, to name a couple) that continue to send video signals via the luminance (marked with 'Y") and the chrominance (marked with "C") channels. In case you didn't know, the chrominance channel is responsible for accurately delivering color info and accounting for the saturation and hue of the images, whereas the luminance manages the brightness and defines the black-and-white pictures.
How does S-Video cabling work?
Back in the day, gaming consoles and TV sets employed composite cables to transmit both these signals together. However, since composite cabling needed to split the image before displaying the actual picture, the result was a grainy image with undefined edges. The S-Video interface on the other hand, keeps these channels separated, thus allowing for a better quality and crisper image.
For composite cables, the luminance channel was designed to block certain high frequency signals for the purpose of limiting overall picture degradation. However, this type of filtering also affected frequency overlapping and, instead of improving, it negatively affected the quality of the image. A further noteworthy advantage of the S-Video cabling is that it allows both low and high luminance frequency data to be displayed on the monitor or TV screen. The direct consequence resulting from here is the enhanced image brightness, usually truer than the one in the original picture.
Types of S-Video cables
The S-Video cables are available in three variations, namely:
- The 4-pin set – the most common setup, the 4-pin plugs are widely spread on most electronic components.
- The 7-pin set – are usually specific to computers. They are compatible with 4-pin plugs, but you will need to ground the extra pins if you want to enjoy a quality video transmission. In general the additional pins allow the cabling to support l2C interfaces and are used for carrying composite video signals.
- The 9-pin set – mainly used with gadgets that employ distinct graphic techniques.
S-Video cables: Pros and cons
Granted, the S-Video interface appears less attractive when compared with high definition connectors like DVI and HDMI. To be more precise, the S-Video cables will provide a poor quality image in contrast with new component connectors because:
- the limited frequency bandwidth
- the chrominance is transmitted via a single wire
- the signals need to be encoded and decoded
Even though nobody is denying that the newer component connectors provide better quality images, it is important to note that S-Video still has one big trump card over the DVI and HDMI, namely the amazing versatility. To put it simply, S-Video cables are still used today for connecting numerous TVs, DVRs, video game consoles, laptops, DVD players or VCRs models. What this means for customers is that once they purchase an S-Video cable for one of their electronics, they will be able to use it with several other devices in their home.