Learn About Composite Video Cables And What They’re Used For
When you look at the back of a television, particularly an older one that isn’t designed to accept HDMI connections, you’ll see all sorts of jacks. It’s quite likely that at one point or another you’ve stood behind a TV with cables in your hand, trying to figure out which ones should be connected where.
That decision can be confusing. Several types of cables use the exact same plug – the one with a thick post sticking out from a circular outer shell, known as an RCA plug – so TVs often have several sets of jacks that look the same, but do very different things.
The cable that’s the subject of this discussion will probably sound familiar, though. It’s the one with yellow molded connectors on each end, and it’s used to send a video signal from a source to a TV or other device. It’s called a composite video cable for reasons we’ll explain shortly. But for a full understanding of composite video, we also need to distinguish between these cables and the ones they’re often confused with.
Composite and Component Video
The two cables most often confused are composite and component video cables and they’re used for the same basic purpose, transferring analog video signals (as opposed to HDMI, which transfers digital video). The facts that their names are similar and they each use RCA jacks and plugs only add to the confusion. The best way to tell the difference is to understand how each cable works, and to do that, you have to know a little about video signals.
There are several types of information required to “assemble” the color video shown on a TV screen: luminance (describing the brightness of the picture), hue and saturation (describing the colors), and the “housekeeping” details that help assemble them all together correctly. As you’d probably guess, you’ll get a better picture if those elements are transferred separately than if they’re all combined into a single signal.
Composite video combines them. The information is sent from the source to the destination on a single wire, and it’s then divided into separate signals once it arrives at the TV set or other device. This is convenient, of course, but it’s not able to produce the high resolutions required for HDTV display; composite video cables will only allow you to transfer standard definition video. As we’ve mentioned, most composite video cables have yellow connectors, and they’re often teamed with red and white audio cables in one bundle. (That adds to the confusion even more, since most audio cables also use RCA plugs.) A component cable is what plugs into the single RCA jack on your TV or device that’s usually marked “video in” or “video out.”
Component video sends each of the video signals separately, on three bundled cables with RCA plugs on either end. (It’s not important to this discussion, but if you’re curious, the cables use what’s called a YPbPr scheme with one cable used to carry the luminance and housekeeping signals and two carrying what are known as the “color difference” signals with hue and saturation information.) The three component cables are normally colored red, green and blue, based on the traditional RGB color scheme. Component video is capable of delivering high-def signals, unlike composite video; since it’s an analog signal it won’t be as high-quality as digital signals transferred via HDMI, but it will look much better than a composite signal. Among other reasons, component signals have additional “comb” filters to prevent the merging of video signals that can lead to signal loss, a typical occurrence in composite cables due to the combination of video signals. If you have a choice, use component rather than composite.
One other quick note: there are also component video cables with five connectors; those simply include the three video connectors plus red and white ones for audio.
To answer the question that’s often asked, composite and component video cables are not interchangeable, even though they look the same. In a pinch, you can try connecting the yellow composite cable to the green component jack – but don’t expect to get very good video, if you even get any at all.
What to Look for in a Composite Video Cable
The ideal composite video cable will be constructed from sturdy, low-loss RG-59/U coaxial cable, suitable for carrying the large amount of video information which needs to be transmitted. If you use a combination A/V composite cable with thinner red and white audio cables bundled with the video cable you’ll sometimes see the thinner wire used for video as well, but that’s not the best choice.
The coax you find in high-quality composite video cables will have solid copper conductors with two levels of shielding to prevent against distortion caused by radio frequency and electromagnetic interference. Most often there will be a layer of copper and aluminum braid shielding covered by a 100% aluminum foil outer shield. A strong PVC (polyvinyl chloride) jacket will cover the cable with molded construction for the connectors, which should be gold-plated for corrosion protection and to eliminate connection noise.
Uses for a Composite Video Cable
The composite video cable is primarily intended for high-quality analog video connections between sources like DVD players, video game consoles or DVRs and TVs or monitors. But it is also perfect for several other uses.
For example, the low loss and high levels of shielding of this cable makes it ideal for connecting a video signal to your home computer or laptop, if the machine has an RCA video-in jack, for high-quality movie viewing (remember, you’ll also need to make separate audio connections). The coax cable is also perfect for transferring audio signals, so it can be used to connect the subwoofer in an audio system or home theater to a receiver or amplifier, for an S/PDIF connection to equipment like digital tape machines, or even as two stereo audio cables to replace cheaper and thinner standard audio patch cables.
The one thing to be aware of: you don’t need to pay a fortune to companies who claim to offer super-duper composite video cables at ridiculous prices. As long as you’re dealing with reputable cable manufacturers (like Cmple) that meet the specifications we’ve mentioned, all composite cables will do the job just fine.