Choosing the Best Video Mixer

Alice Patterson
October 1997

If you've been setting an alarm clock to wake up your audience, or have resorted to bribery to keep your friends watching your productions, chances are you need to add a little extra pizzazz to your videos. Whether you're just getting started in video production or are a well-seasoned camcorder connoisseur, special effects generators (SEGs) and video mixers are two popular products you can use during post-production to put that extra kick into your videos. If you use a computer to edit, there are also a number of special effects software packages available to help you enhance your productions.

Mixers and SEGs are not created equal. Like us, they sport unique features worthy of evaluation before an honest judgment can be made. Before you jump into a major purchase, sit down, pull out your scratch pad and take note. You've got some questions to answer.

First, what type of effects do you want to create? Simple fades and wipes? Or, do you want to create more dramatic scrolls, page-peels and morphs? Do you want to accomplish these special effects with a stand-alone unit, or will you be using your computer to help liven up your production? Are you a novice or a seasoned pro? If you are a beginner, are you willing to tackle a sophisticated video mixer or would you rather start with a simple, no-nonsense unit? There are plenty of choices available--just do your homework and you'll be creating eye-catching effects in no time.

Before we jump into our coverage of video mixers and SEGs, a few clarifications are necessary. Quite often, you'll see the terms "video mixer," "SEG" and "video switcher" used synonymously. While they do perform many of the same functions, there are distinctions between them--differences you need to know about to make an informed purchase.

A true video mixer (also called a "switcher") lets you perform effects--like dissolves, fades and wipes, for example--between two video sources. This is important, because some SEGs can only tolerate a single video source. These single-source units are usually low-cost, and enable you to perform simple effects like adding mosaics or sepia-tones to your productions. Some single-source SEGs might also have basic audio-mixing capabilities that let you combine more than one audio source together. Before you decide to buy, evaluate your mixing needs and make your purchase accordingly.

Today's technology has given the consumer vast choices in the types of effects they can create with their mixers. To cover all of these effects, we'd need more than these few pages--so let's take a broad-scope view of some of the basics.

Fades, wipes and dissolves are among the most basic--but necessary--functions you'll find on an SEG. The fade function lets you make the transition from live video to a plain, colored background. Many camcorders on the market today sport a built-in fade feature; check your camcorder to see if it has one before you buy a special unit to perform this task. Wipes use lines or patterns to replace one image with another. Single-source units that perform wipes will usually fade or wipe the image to a solid color, whereas dual-source units transition between two moving video sources (a process known as A/B-roll). Some units come with literally hundreds of wipe shapes: diamonds, circles or hearts are just a few you might come across. Dissolves allow you to make a smooth transition from one scene to another.

Keying is another effect found on most mixers and SEGs. This effect lets you electronically superimpose an image over a background. Two common types of keys are chroma keying and luminance keying. In a nutshell, chroma keying lets you replace a certain color in your video with an image or another video stream entirely (an effect commonly seen on the evening news, when the weatherman hovers over the computer graphics). Luminance keying is essentially the same thing, only it works on the black-and-white portion of the signal instead of the color.

Features such as paint, strobe and mosaic are other effects you're likely to find on your SEG or mixer. Using a paint feature can give your production the look of an oil painting; strobe effects (also called stop-action effects) often come in low-, medium-, and high-speeds; a "freeze" option will let you stop the action in your video altogether. Mosaic effects turn your video image into small blocks of color. More complex 3D effects, dramatic page peels and "morphs" have also become increasingly popular, and can be found on many of the computer software programs we'll look at later.

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