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.
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:
- Set the assembly deck on RECORD/PAUSE at the point where shot A will begin.
- Determine the length of shot A (say, five seconds).
- Position the tape in source deck A to feed shot A.
- Determine the start point of shot B.
- Position the tape in source deck B to feed shot B plus five seconds (the length of shot A).
- 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.
- 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.
Single-camera B Rolls
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
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.
B Rolls with Two Recorders
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
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.
Tips for Two-tape Shooting
Whether you work alone or with a partner, with two cameras or one, you’re going to end up with at least
two different tapes–that’s the whole idea, right? So here are some tips for wrangling them.
First, label them distinctively. Very, very distinctively. It’s hard enough to keep all your reels
straight when editing. But when you’re juggling A and B tapes at once during real-time shooting, it’s all too
easy to mix them up. To avoid confusion, I color-code the labels. For my A roll, I use the white face and
spine labels that come with the tape.
But for my B-roll tapes, I use distinctive blue-colored labels printed on my laser printer. I get mine from
Professional Label Service (301 570-0774). They make labels for all types of printers–or no printer at
Because my tape spines are color-coded, I can push open the tape bay doors of my source decks and
instantly remind myself which tape is in which VCR. (It may surprise you how easy it is to mix them
A second big problem concerns syncing the tapes. This is not an issue with titles, cutaways and general
shots, of course; but if you make two tapes of the same action, you’ll need to synchronize them in order to
transition between the A and B rolls. Unless you shoot and edit with time code, you’ll find that aligning two
tapes of the same action takes a bit of ingenuity and practice.
The easiest way to do this is by using a sync point: an identical and easily identifiable instant on each
tape. The classic way to create a sync point is by training both cameras on a clapper board while an
assistant snaps the clapstick down onto the board. The result is a single frame, on each tape, during which
the stick makes contact. By lining up this frame on both tapes, you synchronize them.
An ingenious alternative once suggested in this magazine is to have both camcorders tape the flash of a
still camera. Because the actual flash is so brief, the resulting flare begins cleanly on a single video
Even with clear sync points, it can be tricky to align A and B tapes and keep them running in perfect
sync longer than a few seconds. So what follows are editing rather than shooting tips, but as long as we’re
on the subject, we might as well include them.
A Short Trip to the Edit Suite
First, if at all possible, use identical VCRs for both A and B source decks. Different VCRs have different
run-up times and even different delays between the instant a command is sent and the instant it takes effect.
Suppose you push PLAY on both decks at once. If one takes half a second longer than the other to begin,
you’ll be that far out of sync–and in footage with on-screen speech, half a second is way, way out
If you are out of sync–often because you don’t have a sync point to start from–you can align your
source decks on the fly, like this:
Line up the decks as well as you can by eyeball, as far ahead of the cut point as possible. This can even be
as long as a minute or two if the shots run that long. Then start the source decks together.
Watch each deck on its own monitor and listen to the on-camera speech, if any. (In some cases, it’s helpful
to turn off the sound of one roll and listen to A while watching B.)
Identify the deck that’s lagging behind and "bump" its tape by tapping the visible fast forward (or double
speed play) control and then very quickly tapping it again to resume normal speed. With practice,
you’ll find that you can pull the lagging tape up into sync before you begin recording.
One last trick before we leave the editing bay: when you have a choice, make transitions between shots
of the same action from a close shot to a wide shot, but continue the sound from the close
shot over the wide shot. Because subtle lip movements are very hard to see in wide shots, small
mismatches are often undetectable.
So there you have it: several ways to create B rolls for editing with first-generation transition effects,
plus a handful of editing tips at absolutely no extra charge. It’s not surprising that this camera column
sometime strays into editing. After all, the pros know that to make good videos, you have to keep all three
production phases in your head at once.