Camera Work: As Easy as A/B Roll

A couple of columns back, we discussed using your camcorder for simple editing, so now let's move a step upscale to talk about creating the raw materials for post production using A/B-roll techniques.

If you're wondering why a column on production methods is messing with post production, fret not. Today, we're less interested in A/B-roll editing than in A/B-roll shooting.

Yes, shooting.

But before we plunge in, here's a lightning review of what so-called "A/B-roll" editing is all about. A/B- roll editing means connecting two editing source decks to a switcher that can send the signal from deck A to the assembly deck, and then switch on command to the signal from deck B instead. The basic setup is diagrammed in figure 1.

Why bother? So that you can use the switcher to create transitions like wipes and dissolves between shots. To make these effects look right, you have to run both the outgoing and the incoming shots simultaneously as you make a transition from one to the other. Here's the basic procedure:

1. Set the assembly deck on RECORD/PAUSE at the point where shot A will begin.
2. Determine the length of shot A (say, five seconds).
3. Position the tape in source deck A to feed shot A.
4. Determine the start point of shot B.
5. Position the tape in source deck B to feed shot B plus five seconds (the length of shot A).
6. Roll both source decks A and B together, with the switcher set to feed A to the assembly deck. At the edit point, start recording shot A.
7. At the out point of shot A, switch to feeding source B, via dissolve, wipe or other transition effect.

If you've correctly allowed for the length of shot A, shot B should begin recording at the right point. Look at figure 2 and you'll see that the process is easier to visualize than to verbalize.

But wait a minute: if source A is the original camera tape you're editing, what's source B? Where do you get that second tape that you need to do A/B-roll editing? You could make a duplicate of your camera original, but that would mean losing a generation of picture quality. It's better to create a first-generation B roll while shooting the program.

Which brings us back to our main subject.

In most cases, you have only a single camera available when you shoot, so let's see how you can make two tapes with just that one machine. There's a wide variety of material you can shoot on a B roll: establishing shots, POVs (points of view), sequence openers, cutaways, general shots, titles and many others.

The most common use for A/B transitions like wipes and dissolves is to signal the start of a new part of a program--a new sequence. "Let's go open presents," says the birthday parent to the dining room full of kids scarfing cake and ice cream; and, thanks to the DVE (Digital Video Effect) capability of your switcher, a shot of the living room flip-flip-flips onto the screen to replace the dining room shot.

How did you get a first-generation living room shot for the B roll? Simple: on your way from the dining room, you replaced your A camera tape with a B-roll tape. Then, after recording the children entering the room on the B roll, you quickly swapped it for the A roll and kept on shooting.

By doing this every time your video subject offers a change of time, place or activity, you can create a B roll containing the opening shot of every sequence.

You may also want effects within sequences as well, and the easiest way to create B roll footage for them is to shoot cutaways: inserts and color shots. At the birthday party, for instance, you could shoot the glittering pile of presents waiting in the living room on a B roll, at your convenience. Then capture both dining room and living room events on the A roll. When you edit the program, dissolve from the A-roll dining room to the B-roll presents before cutting back to the A roll as the kids enter the living room.

To use a B-roll cutaway at a wedding, suppose you want to dissolve from the bride and groom starting back up the aisle to a shot of them emerging from the church. You're working too fast to swap camcorder rolls on the run, so you record both shots on the A roll.

But, smart videomaker that you are, you captured a beautiful B-roll shot of the church exterior back before the wedding party arrived. Later, in the editing bay, you can dissolve from the A-roll aisle shot to the B-roll church exterior; then cut back to a closer A-roll shot of the couple coming through the door.

Another form of cutaway is the general shot: a wide shot recording ongoing activity. Whether you're taping a banquet, a wedding reception, a birthday party or the grandstand at a little league baseball game, the action is often so repetitive that you can insert it almost anywhere in your video.

The trick is to capture the essential action first; then you can position the camcorder for an overall view of the scene, pop in the B roll and grab at least five minutes of footage. Because the wide-angle shot will probably lack very distinctive actions by the subjects in it, you can DVE to it any time you need it. (You can also do double-duty here by recording ambient sound of the location, for use in audio editing.)

The most obvious subject matter for a B roll is titles, whether live, on cards or superimposed over live action. Like cutaways, you can shoot titles without switching rolls in mid-shoot because you tape them before or after the actual events.

To make a live-action B-roll title for a birthday, you could shoot a tight insert of hands opening a card envelope addressed to the birthday person. For an anniversary party, you might tape the announcement and picture in the local paper ("Shane and Shelley Sheetrock Celebrate their 50th").

You can also make titles on solid color cards, whether physical boards from an art store or virtual cards: color backgrounds created by your computer or stand-alone video titler. By treating the camcorder or title generator output as if it were a B roll and recording it directly, you'll get a higher quality title.

But if you want to superimpose titles on live action, it's sometimes better to do so on a separate work tape and then use the composite as a B-roll editing element. Because of the visual complexity of the title- plus-live action information, the slight quality loss is usually not too noticeable.

But whether you use B-roll footage for sequence starters, cutaways, general shots, titles or what have you, the principle is always the same: by creating a B roll, you can perform editing transitions between two first-generation tapes, even when shooting with only one camcorder.

If you can get the necessary hardware, you can obtain A and B rolls of the same material by shooting it with two cameras. But before we cover this approach, consider a way to get two first generation tapes from a single camcorder.

The trick is to cable the camera's audio and video to a VCR and record everything on both machines at once. As a result, you can obtain two identical first-generation copies of 100 percent of your footage. This gives you unlimited freedom to make transitions anywhere you please.

But if the advantages of two-tape recording are first generation tapes and complete A/B coverage, the obvious disadvantages are power requirements and loss of mobility. Most VCRs require 120V AC power, and that means you're tied to a wall outlet, so lotsa luck shooting that trip to the zoo.

But if you want to make a habit of laying down a dupe roll, here's an idea. Panasonic, RCA and other manufacturers make VCRs combined with thirteen-inch color monitors. Some of these can switch between 120V AC and 12V DC power. Check them out before you buy, as many of them are players only.

With many of these setups, not only do you get a second recorder; you also get a usable quality color monitor on which to check your footage. (No industrial production crew would ever work without a monitor.) Several companies advertising in this and other magazines offer 12V battery packs with enough capacity to power the VCR/monitor. To wrangle the batteries and the unit itself, you'll probably want a wheeled cart as well.

Which brings us to the second drawback, mobility. Even if you can free yourself from wall power, you're still harnessed to a cart full of equipment by cables that shouldn't be more than 20 feet long. (Even with Y/C connectors, cable runs longer than 20 feet start to degrade video quality.)

One solution involves a compromise: roll camcorder and VCR together whenever you don't require total physical freedom. But when you need to range widely around the shooting location, cut loose from the VCR and shoot A roll only. If you plan it adroitly, you should be able to get enough B roll footage for editing transitions.

But no matter how ingeniously you shoot, it's obviously easier to create a B roll by using a second camera. You can do this with a shooting partner--or even without one.

If you're working alone, set up your B-roll camcorder on a tripod to record a wide shot of the event, turn it on and let it go. By capturing all the action, you can transition to a B roll shot at any point you like. (And once again, you'll get all the ambient sound you could ask for.)

When you're working with a partner, be sure to develop a game plan before the shoot. If both of you are blazing away ad lib, you're likely to overlap coverage where you don't need it and miss the action where you do. It's better to assign general coverage to one camera, cutaways and color shots to the second and two-camera coverage of key moments during the event.

To improve communication among multiple camera people, my students wear wireless headset walkie- talkies. Radio Shack makes an inexpensive version of these units that reach about 300 yards outdoors, and pass through at least two to three interior walls.

Use them carefully, though: the camcorder mike will record the operator's speech, and even the words coming in on the headphone, if the volume's too loud. This system works best when a single video director talks one-way to two or more camera people.

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