Video signals have an annoying tendency to degrade in quality every time you copy them. This tendency-known as generation loss–is the bane of video editors everywhere. To avoid its effects, editors find themselves playing a game, often going to great lengths in hopes of achieving the best-looking final product they possibly can.
Someday, you might have to take your chances in the generation loss game. You’ll test your luck as you balance tape formats, lighting conditions and editing equipment in an exciting race to the finish line. Your prize? The highest quality video.
Unless you’re working exclusively with digital video, you are going to have to deal with generation loss every time you edit. Follow along and we’ll show you some of the tricks that good players use to beat the odds.
Start with the Best Equipment
The first stop on the way to reducing the effects of generation loss is to start with the best camera and tape format you can get your hands on, thus maximizing the quality of the footage you edit. If you can manage to get a camcorder with three CCDs, do so; this will bump the image quality up another notch. Not in your budget? Use the best equipment you have access to, or consider renting a camcorder.
Since most of us won’t be in the market for industrial BetaCam gear, that leaves us with the DV, S-VHS and Hi8 formats as our best options for image quality. All three have a high signal-to-noise ratio (S/N), expressed in decibel (dB) measurement. The higher the dB measurement (or rating), the better the video these machines will produce. Noise is any undesired electronic signal that creeps into your video, either while you record it or when you run it through another piece of equipment. Hint: minimizing the electronic noise that creeps into your signal as you edit is the best way to win the game.
Light it Right
Remember, you want the source footage (the stuff you’re going to tape) to be the cleanest copy it can be. That means you want plenty of light on your subject.
Some manufacturers really play up their camcorders’ so-called low-light (lux) ratings, but in most cases these figures are misleading. The bottom line is that you can’t get a good video image without plenty of light, regardless of your camcorder’s lux rating.
Camera-mounted lights are good for objects, but they tend to make people squint. Stationary video lights are better. These inexpensive workhorses will provide an abundance of light and allow for subtle changes and effects. But you don’t need to invest in special video lights. Stand-mounted shop lights, living room floor lamps or even a well-aimed desk light will improve an otherwise dark shooting situation.
Avoid using your camcorder’s gain-up switch unless it’s a do-or-die situation. This feature, designed for shooting in very low light, will make your source footage look like third-generation VHS before you start editing.
TBC or Not TBC?
A video signal has high frequency pulses that line up the signal with the VCR that’s recording it and/or the monitor that’s displaying it. Keeping your pulses (known as vertical sync pulses) pure will greatly reduce generation loss. That’s the job of the TBC, or time base corrector.
Time-base correctors (TBCs) eliminate pulse error, which is created by most video gear. Imperfections in the machinery can cause pulses to time too soon or too late, throwing off the processing of the signal.
Duplicate this error a few generations and you’ll have jagged edges, liquidy-wavy images and rolling bars in your video. Keeping your equipment fine-tuned helps, but a time-base corrector is the only way to eliminate the problem completely.
Good Cables are Short Cables
Cabling is to video what strings are to a guitar. The cheaper they are, the more noise you will suffer.
Never–and I mean never–use RF cables to copy your video signal. Sure, they’re cheap, but they also cram the audio and video signal through a maze of circuits. Composite cables (usually with RCA or BNC connectors) are better, and S-video cables are best for most consumer-level gear.
Most of these cables come in short lengths. This is good, because long cable lengths can increase the noise in your signal (and therefore compound the effects of generation loss).
The Fire in the Wire
If you’re using a digital camcorder, you might have access to that wonder of modern technology, the IEEE 1394 FireWire serial data cable. If you have a DV camcorder with an IEEE 1394 DV in/out jack, and you have another camcorder, VCR or DV capture board that also has an IEEE 1394 jack, you can make a purely digital connection using a FireWire cable. This means you can make dubs that are completely free of generation loss. That’s right; go ahead and dub ten, fifteen, even twenty generations with FireWire; the copy will look exactly like the original.
Eliminate Black Boxes
It’s a good idea to limit the number of video effects devices you use in your productions. Processors, mixers, and titlers all have their magic–and all require that the video signal travel that extra set of circuitry.
Try and cut down the number of devices you run your video signal through. If you need to add titles to a specific part of the tape, run the video through the titler only at that point instead of running the entire tape signal through until you reach that point.
Nonlinear Generation Loss
Some videographers bemoan nonlinear digital video editing; others can’t stop praising it. How about being able to go to that piece of captured and digitized tape in an instant? Or how about re-cutting a few select portions of a program without shuttling through all those tapes to re-edit?
Though it does have many advantages, nonlinear editing does not completely eliminate generation loss problems. When you pass your signals through the video capture card’s circuitry, you’ll get added noise, just as you would when using any other type of circuitry. Also, though it isn’t technically correct to call it generation loss, digitized video suffers from its own special kind of loss that results from compressing the video data down to a usable size. In general, the more you compress the video, the worse the image looks.
Plan Ahead to Win the Game
One way to insure a clean signal recording is to plot out all the elements your video signal will pass through to make your image. Because unforeseen events do occur and things pop up that you didn’t think of, it helps to write everything down from the first shot to the last edit.
Before you shoot, visualize the final outcome of the taped footage. In so doing, you may save a few generations–and end up a winner in the generation loss game.
Larry Burke-Weiner is a photo illustrator and video producer.
How do you score in the generation loss game? Write to In Box, Videomaker Magazine, P.O. Box 4591, Chico CA 95927 or send e-mail to firstname.lastname@example.org.
Generation Loss Game Rules
- Select a game piece for each player (up to 6).
- The magazine’s subscriber goes first. If more than one player is a subscriber, roll the die to determine who goes first.
- Roll a single die on each turn.
- Advance the number of spaces indicated by the number on the die.
- Take the action specified by the square on which your piece lands.
- The game ends when all players reach the finish.
- The winner is the player with the lowest number of generation loss points.
Generation Loss Scoring
1-3 Looking fabulous!
4-6 Not too bad.
7-9 I’ve seen better.