A B
angles of the DJs (Figure A) and the crowd, an
overhead camera looked down (Figure B), and a cam
mounted on a robotic dolly I built ran back and forth
on a track in front of the two DJs, allowing us to get
some very dynamic, moving shots. The speed and
direction of the dolly were controlled by MIDI as well,
with the ServoCenter driving a beefier servo that
turned the dolly’s rubber wheels.
Try This at Home
Working on the Hard Sell tour made us realize the
possibilities of MIDI cams. With setups like this, just
1 or 2 people could provide dynamic, multi-camera
video coverage for all kinds of live events: sports,
performances, contests, demos, even pranks. Now
I also wonder how many tiny robotic cameras I could
manage at once.
Running VVVV on a laptop, you can eliminate the
need for the high-end hardware we used on the
Hard Sell tour. I concocted a work-alike system that
uses just a PC, the servos and ServoCenter, and a
webcam for video capture. Computing power is a
factor, but a fast computer can handle simple mixing with 2 video feeds. Just make sure the webcams
are different brands, so that Windows won’t see
them as having identical IDs (I have heard that
Fire Wire webcams don’t have this problem).
Mixing the Video
The next question was how to switch or mix the
multiple video feeds for projection onto the big
screen. With our 9-cam Hollywood Bowl setup we
used a security camera DVR, which let us switch
feeds and also record all the cameras — the entire
show (albeit at low quality) — direct to a hard drive.
At other shows we used an Edirol V- 4 video mixer,
a favorite VJ workhorse that can switch, mix, and
apply effects to 4 simultaneous video streams.
The mixer let us intercut the cam feeds, morph
them into more abstract patterns, and add in any
DVD visuals we queued up.
As we did more shows, we devised new ways to
bend the technology to our will. We tried recording
the MIDI control messages with music software on a
laptop, then playing them back as pre-orchestrated
camera moves. Also, I had been experimenting
with VVVV, a free software toolkit for prototyping
multimedia applications. I wrote VVVV routines for
my laptop that generated MIDI commands to move
the cameras in patterns, such as sine waves.
After some more tinkering, I was able to bring camera video streams into my laptop, then manipulate or
mix them with other graphics, all in VVVV. (You can
do the same thing with other software as well, such
as Pure Data, Max/MSP, and Quartz Composer.)
MATERIALS AND TOOLS
USB webcam Most computers will be overwhelmed
by video coming from more than 2–3 cameras.
Servomotors, standard hobby size ( 2 per camera)
I used Hi-Tec model #HS-645MG.
Pan-and-tilt brackets to fit the servos. ServoCity part
#SPT100 ( makezine.com/go/brackets)
ServoCenter full package, MIDI $90, item #SCPMIDI
from tech.yostengineering.com. This includes the
controller board, AC adapter, MIDI cable, software,
and documentation.
USB-MIDI interface I recommend the M-Audio Uno.
Windows XP-based PC VVVV doesn’t run on Vista.
Project box, 4"× 8"× 2" Plastic is easiest to work with.
Standoffs with matching nuts: 1¼" ( 4) and 2" ( 4)
Electrical tape
Double-sided tape or velcro tape, or even zip ties
Phillips screwdriver, slip-joint pliers
Drill with 1"– 3" step drill bit
131 Make:
