Video Cables & Connections

As video creators, we all know that finding a subject and getting it on tape are only the first steps in a long process. Back at the editing station, we still have to wrangle with an array of cables, connectors and communication standards to get from the raw material to your finished product.

In this article, the first in a two-part series, we’ll look at the most widely used video connectors and standards. The discussion below puts these in order from best to only so-so for video applications. In part two, we’ll focus on the audio side of the equation.

Are All Cables Made the Same?



There are wide variations between cables made by different manufacturers, and it’s undeniable that some are better than others. You’ll often see an emphasis placed on gold connectors; these can be helpful in avoiding corrosion at the contacts. (Still: How often have you ever seen corrosion on your cables?) Internal construction is also important. Look for an indication that wiring is of the appropriate gauge and resistance; analog video devices use 75 ohm impedance wire made for video transmission, not audio (that’s most important with RCA cables). And whether it’s an RCA or a FireWire cable, look for plenty of insulation – some manufacturers use almost none, and it makes a difference.

The Long and Short of It



Shorter cables are always better. Since all connecting cables, including FireWire, are subject to some degree of electrical and magnetic interference, it’s important to use the shortest cables you can; the longer the cable, the more the signal deteriorates and the more chances there are that your video will pick up interference. Using thicker, heavier cables will also help. Thicker cables are more heavily shielded than thin ones, protecting your video better from invading signals.

USB Transfer



USB is a relatively slow data transfer protocol; it moves data at only 1.5 MB per second, as compared to FireWire’s maximum of 50 MB per second. Still, USB is universal on newer computers and can be used to transmit compressed video data (or any other kind of data, of course). Watch for more video applications to emerge with the faster USB 2 standard.

FireWire



FireWire is the gold standard for low cost, high quality digital desktop video connectivity. Formally (and formerly) known as IEEE 1394, this communications protocol was invented in the mid-1990s by Apple Computer and is marketed by Sony as i.LINK. It’s ideal for getting video data from tape to your video-editing computer, and then back again.

How It Works

  • Carries digital information between devices (e.g. two computers or an external hard drive and a computer) that understand the IEEE 1394 communications protocol.
  • Provides a fully digital pathway; signal degradation and other problems common to analog connections aren’t an issue.
  • As accurate as a hard drive transfer.
  • For video, FireWire transfers Digital Video (DV) from a Mini DV camcorder, including video, audio and timecode information. It also supports device control of camcorder via software.


How It Connects

  • Ports are built in to most digital camcorders and many new computers. Accessory cards are also on the market.
  • Connectors come in two forms – four-pin and six-pin. The tiny u-shaped four-pin connectors are typically found on camcorders; the larger rectangular six-pin connectors are often used at the receiving end on computers and internal cards.
  • Cables come in three flavors – four-pin to four-pin, four-pin to six-pin, and six-pin to six-pin.

How to Use It

  • Connect a camcorder to a computer with a FireWire cable and then power on the camera (“hot-plugging”) to activate a bi-directional DV stream.
  • Link two digital video devices to make backup clones of important tapes.

How the Cable Measures Up

  • Cables are lightly shielded, so magnetic or radio frequency interference from speakers and televisions can cause signal drops.
  • Four-pin connectors are extremely small and fragile, leaving them vulnerable to early failure.

Component



True component video connections separate the video signal into its YUV components and is a very high quality connection often found on modern DVD players and higher-end televisions.

How It Works


  • As with S-video, the Y=luminance. U (Cb) and V (Cr) are color difference signals. The U and the V do not correspond to blue and red.
  • By separating the signals, less interference and a clearer picture are possible.

How It Connects

  • Each component is carried on a pair of separate wires, often connected with RCA jacks.
  • On professional production equipment, BNC connectors are sometimes used.

How to Use It

  • Used to connect some professional-grade video equipment.
  • Also often used on DVD players and newer televisions.
  • Some computer monitors also use it.

How the Cable Measures Up

  • Robust cables do not use delicate pins.
  • Since there are three pairs of wires, cables tend to be thicker.

S-Video



S-video, or Y/C, connections carry high-quality analog video information between camcorders,
S-VHS VCRs, digital VCRs and high-end televisions and video monitors.

How It Works

  • Preserves separate luminance (the Y part) and chrominance (the C part) image information, which is naturally separate on tape and also inside televisions.
  • Two-signal system makes Y/C video cleaner, sharper and higher in resolution than composite video.

How It Connects

  • Video is carried over a two-wire cable that terminates in round male four-pin DIN connectors; compatible camcorders and VCRs are equipped with female four-pin connectors.
  • One wire carries luminance information, and the other carries chrominance. The other two wires are ground wires.
  • The plastic tab on the connector allows you to line up the cable and the socket before forcing them together.

How to Use It

  • Used with analog VCRs and televisions.
  • Great for monitoring an analog version of the FireWire video stream that runs between your camcorder and your computer during editing and playback.


How the Cable Measures Up

  • Four-pin cable end is fragile.
  • Cable is actually two single-wire cables molded together, so chances for magnetic and radio frequency interference increase. Shorter cables help reduce the likelihood of receiving interference and signal loss.

Composite



Composite RCA connectors are everywhere; they are cheap, simple and widely compatible across a range of devices and manufacturers. Their video performance is only so-so, however.

How It Works

  • Cables are single-wire, which means they must carry a blended or composite video signal with both luminance and chrominance information.
  • Cables pass along a second generation signal that’s composited by the originating device and must be un-composited by the receiving device.
  • Some signal loss, image degradation and color bleeding is common.

How It Connects

  • Pin-and-cuff design couldn’t be simpler to use; male cable ends plug into the female device sockets.
  • Central conductor carries a frequency-based electrical signal between devices.
  • BNC connectors can also be used to transmit composite video, but terminates in a highly durable locking connector that’s found mainly on professional equipment.

How to Use It

  • Use to monitor and dub video when S-video connectors aren’t available.
  • Can sometimes be vital, since not all camcorders are digital, and not all digital camcorders provide S-video sockets.
  • Found also in three-part A/V camcorder output cable with a 1/8″ mini-plug at one end and three RCA connectors at the other.

How the Cable Measures Up

  • Vary widely in quality, length and best use. Not all RCA cables are good enough for video.
  • Use cables specifically designed for video signals; these should operate at exactly 75 ohms of impedance, and they should be thoroughly shielded from radio frequency and magnetic interference.
  • Look for durability in the metal connector ends.

Radio Frequency (RF) / Coaxial



One of the oldest kinds of video transmission, radio frequency (RF) video transmits analog signals in the high frequency range of broadcast television. It’s inherently lossy and prone to degradation and interference, making it useful only as a last resort. Analog RF signals should not be confused with a high-quality digital connection.

How It Works

  • RF bundles together video and audio signals into a single transmission of high-frequency radio waves, and sends it to receiving devices like cable boxes and televisions.
  • The bundled signal is then converted back into usable video and audio information and rendered on screen or tape.

How It Connects

  • Coaxial cable has a copper F-pin with a free-turning threaded sleeve on the cable end; this fits the threaded receptacle on televisions and VCRs.
  • Screw these together carefully, since the copper F-pin is extremely fragile and easily bent.
  • Only devices that generate and understand RF video signals, like VCRs, televisions and some older camcorders that came with RF adapters, can accept coaxial connections.

How to Use It

  • Use when there’s no other choice.
  • Connect to a television using the S-video or RCA inputs on a pass-through VCR with a coaxial connection.

How the Cable Measures Up

  • Stereo speakers, electrical devices, and even airplanes passing overhead can all interfere with RF signals.
  • Look for high-quality materials, a durable center pin, and plenty of shielding to minimize interference.

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