An exercise in split screen effects
using Video Action for PVR or EditBAY
Its one of the oldest
special effects ever, a split screen. The original Star Trek
series featured the effect in no less than three episodes. Recently,
ABCs Fantasy Island re-make showcased Malcolm McDowell
playing chess with himself. Several motion pictures use one
form or another of the effect, including Big Business, Multiplicity,
plus Back to the Future II and III. Disney has
used it to produce the Parent Trap saga with a total
of five films. Today we will be using Video Action to create
a simple split screen effect. You will find there is very precise
control over the effect, so with a little creative planning,
your talent can move about the set quite freely without destroying
The first thing to consider when
developing this effect is the staging. Keep in mind that your
actor must observe a few rules to accomplish the illusion. First,
the threshold of the effect must not be crossed. Second, props
that appear in the effect must remain stationary. Lastly, the
shots must all have the same lighting and depth of field. In
addition, the camera must be steadied on a tripod and must not
move from shot to shot.
In this example I have set up the
camera to capture three separate areas for the talent to perform,
including a hallway, a doorway and a wall. The first thing to
do before the shoot is to turn your cameras autofocus
feature off. Instead, at the beginning of the shoot, zoom in
on your subject, focus and pull back. This is called pulling
focus and it will help keep maintain the depth of field for
all your shots. I also shut off my cameras automatic exposure
The first shot consists of the
actor knocking at the door and then making eye contact and waiting.
The second shot has the same actor opening the door, making
eye contact, and then walking down the hallway.
After capturing the clips, the
first thing we want to do is match up the actions. Drag the
clips to the timeline and drop an index marker on each clip
where the actor first makes eye contact. This gives the illusion
that they actually see each other.
Next, move the second clip onto
overlay track V3 under the first clip and align the Index markers.
To composite these two scenes,
I will apply the Gradient Wizard filter to the clip on track
V3. This filter is normally used to create a smooth gradient
from one color to another. But is this case we will use its
alpha channel feature to create a moving transparent matte.
We begin by selecting the Transparency
Only option. Already you can see part of the effect.
The option to Repeat Gradient
Forever is also turned off. Next, I adjust the Gradient
Cycle so that we have a blended threshold. This will help hide
the threshold if the lighting is not exactly the same in both
Here you can see that the lighting
did indeed change in the shots. A hard edge is very clear in
the upper left corner. The blended soft edge crossing the door
is virtually invisible. Notice the legs?
Next, I drag the hard edge node
to the right-hand edge of the image. The soft threshold is lined
up with the right-hand frame of the door. This will be the threshold
of the split screen. The filter uses keyframes, so the position
of the threshold can be moved over time. This will come in handy,
because our actor has already broken one of the rules. His hand
briefly crosses the threshold of the effect to knock at the
At this point I select the Keyframes
button so that I can change the position of the threshold. The
threshold is dragged to the left hand side of the door frame
at the first keyframe. This allows the actors hand to
safely reach in and knock at the door without disappearing into
Now I drag the percentage cursor
to a point after the knock where the actors hand has moved
beyond the frame of the door. I then add a new keyframe. By
copying the settings of the last Keyframe to the middle keyframe,
the position of the threshold will hold stationary until the
end of the clip.
The threshold moves across the
door from left to right allowing the actor to reach in briefly
and knock at the door. Once the threshold is there the door
is opened by the actors double..
The effect is now complete. With
a little planning and imagination, split screens can provide
a very unique visual treat.
Watch Your Props
Props that move, like the door
in this example, need special attention because they can easily
destroy the illusion. For example, I could have keyframed the
threshold back over the door again, to allow the actor to follow
his double around the corner of the hallway. The only problem
was with the door. Its closed on the first clip and was
left open at the conclusion of the second clip. The different
positions of the door would have ruined the effect as the actor
Now that you know how to make twins,
it not too hard to create triplets. Can you figure out how I
To see a video clip (1274k, mpeg
format) click here.
Need a filter for doing splitscreens in Video Action (4k)? Shift
You can find out more information
about Video Action for PVR and EditBAY at http://www.dps.com.
The author welcomes questions and
comments. He can be reached by email at firstname.lastname@example.org
Video Action for Windows NT is the professionals choice
for broadcast quality digital video editing. Together with DPS
award winning hardware Video Action delivers a full featured
editing solution. The software package comes bundled with all
of DPS desktop products DPS EditBay, DPS SparkPlus,
DPS Perception, and DPS real-time editing solutions the
DPS Perception RT and DPS Perception RT3DX. The power of this
software is apparent when it is combined with DPS award
winning hardware. DPS Video Action software makes it easy to
move from one DPS hardware platform to another without the need
to learn a new editing program or user interface.
About DPS DPS is a leading designer and manufacturer
of electronic hardware and related software used for recording,
editing and processing broadcast quality video and audio material.
The company has three business segments: Broadcast, Professional
Post-Production, and Security. DPS products are used throughout
the world by television broadcasters, video production studios,
post-production facilities and by the computer-based desktop
video production industry. Visit our web site at www.dps.com.