An introduction to Videomaker's Guide to Video Connectors
Despite the recent popularity of wireless systems such as Wi-Fi, Bluetooth and infrared technologies, wires are here to stay for some time to come.
Is your mind as tangled-up about cables as that rat's nest of cords behind your computer and its peripheries? We're here to untangle the confusion and rumor around wiring in both production and post-production as well as helping you choose the proper hook-up for all the audio and video home gear you have accumulated. Once you know exactly what you need (or don't need), check the manufacture's guide to find out who is making cables and adapters that bring your gear together.
Let's start with composite cables (actually, we'll be talking about the whole cable assembly, which is a combination of a cable and a specific connector at both ends), the most common and inexpensive way to get your signal from one place to another. These are, however, the most susceptible to outside noise such as RFI (Radio Frequency Interference) or EMI (Electromagnetic Interference). The most common cable in the audio/video world is the RCA. Also called a phono cable, it carries the entire video signal on one cable (yellow) while the right (red) and left (white) channel audio are each carried on their own cable. The BNC cable functions in the same way but has a bayonet connector for a more reliable connection. Shielded well, these cables are more than adequate for home A/V use and most consumer production and post-production applications.
S-Video or Y/C cables are a step up from composite. An S-Video cable only carries the video signal, breaking it up into two components: luminance (brightness) and chrominance (color). Found on higher-end A/V equipment, S-Video offers marked improvement over composite cables, with noticably less dot crawl or distortion between colors.
Component cables look similar to RCA composite cables but usually have a different color code system. This three-wire cable is only for video, breaking its signal into three parts making its image quality superior over both composite and S-Video. You might see these referred to as Y,Cr,Cb or Y,Pb,Pr. Higher-end DVD players and HDTV tuners will have component connections.
Another common consumer cable is the 1/8" mini (3.5mm). Found on devices such as MP3 headphones and some consumer end microphones, these cables are unbalanced, making them more susceptible to outside interference. The general rule is the shorter the cable, the safer they are from interference. A five-inch cable from hot-shoe mounted shotgun mic to video camera should not be a problem but you should avoid a 30-foot cable from a stick mic to camera.
1/4" phone connectors, used by electric guitar players or those old telephone switch board operators, can be either balanced or unbalanced. The balanced version will have a tip/ring/sleeve configuration on the tip of the connector as opposed to just a tip/sleeve of the unbalanced.
XLR cables are the cord of choice in the pro audio world. These balanced cables have a ground plus two identical signals running 180 degrees out of phase with each other and reinterpreted on its receiving end to check for accuracy. They also have locking connection points and can run for long lengths (over 20 feet), unlike 1/8" cables.
VGA (Video Graphics Array) is an analog computer cable that handles resolutions from 640x480 and beyond. It uses a 15-pin connector and is the PC video display standard of the moment.
DVI (digital video interface) cables look a bit like VGA but are slightly larger. They can carry both analog and digital signals. They shine in their digital-to-digital relay providing nearly zero signal loss. Able to process large amounts of data at high speeds, these cables will eventually replace VGA and other analog display cables. There are a few different types of DVI connectors, so check your manual and devices carefully before trying to force a cable into a port.
HDMI (high-definition multimedia interface) is very similar to DVI but is smaller and only comes in one size connector. These digital-to-digital cables also carry up to 8 channels of digital audio, which make them popular with owners of plasma televisions, LCD TVs, DVD players and other high-end consumer gear.
USB (universal serial bus) connections are commonplace among computer peripherals such as keyboards, mice and external hard drives. Found on most computers made after 1997 or so, USB 1.1 transfers data up to12 Mbps depending on the type of device. USB 2.0 is 40 times faster (in theory) and has a maximum transfer rate of 480 Mbps, making them suitable for hard drives, video, and other high-data transfer needs. You can attach up to 127 devices to one USB port (with a self-powered hub), devices can be daisy-chained (one connected to another and to another, etc.) and they are hot swappable (can be plugged in and out without turning your computer off). It is highly recommended that you use an active repeater cable when you use USB cables longer than 16 feet.
Like USB, FireWire (a.k.a. iLink or IEEE 1394), has just been upgraded. There is what is now referred to as FireWire 800 (800 Mbps), twice as fast as the original FireWire and doubling the maximum length of cable to 15 feet (3300' with an optical repeater). FireWire is hot swappable and is the connection of choice for consumer digital video equipment. These cables come with a four-pin or six-pin jack. The six-pin connector carries electricity to the peripheral device, while equipment that doesn't need power, like consumer digital camcorders, uses the four-pin port.
Connectors and Adapters
Generally speaking, it is much easier to adapt analog cables to each other than the cables in the digital world. XLR to 1/4" phone, 1/8" mini to XLR and RCA to S-Video are all possible. You'll want to keep an eye on balanced vs. unbalanced and line-level vs. mic-level interconnectivity. There are adapters to convert a stereo signal into a mono signal and there are Y-cables to put a mono signal on both stereo speakers.
Cables in the digital world are less compatible but there is less of a need to be. You can't convert USB to FireWire, but most computers these days can work with both. USB 2.0 plays well with USB 1.1 as FireWire 800 gets along well with FireWire 400 devices.
So Get it Together
Your many thousands of dollars worth of video, audio and television equipment is not worth much if you don't have a command of the cables and adapters that make them work together. And although there may be differences in product quality from the manufacturers of these connectors (not to mention cost differences), there is much controversy over how well the human ear and eye can really tell the difference (do a Google search and see). We'll leave the gold-tip, thicker cable debate for another article; first, just get all of your machines communicating.