TM
USING Deuce VIDEO SCALERS IN
VIDEO CUBE AND VIDEO WALL
APPLICATIONS
MARKET: Presentation
DOC. NUMBER: T-05
The Video Wall, an increasingly popular form of
large-screen display, is actually a collection of smaller,
rear screen video projection cubes, typically config-
ured in a grid pattern (2x2, 3x4, 4x5, 6x8 etc.). These
cubes feature either CRT, LCD or DLP projectors that
display a progressive scan RGB signal. In order to
turn these individual cubes into a larger, synchronized
display, a “video wall processor” segments and dis-
tributes the video source as a single, large picture
across the array of cubes. It also provides the ability
to size, position, combine and sequence up to four
video sources for display on the video wall.
This TECHnique illustrates how CSI’s family of
®
video scalers may increase functionality and
improve performance of a video wall installation. By
converting interlaced NTSC and PAL video sources
to progressive scan RGB, Deuce scalers provide both
the video wall processor and the video cubes system
with increased flexibility and better picture quality.
need for more than four video sources to be displayed
simultaneously is not uncommon. However, this ex-
ceeds the capabilities of a video wall processor. For
these applications, an individual video scaler desig-
nated for each monitor or cube would be an effective
solution.
Regardless of the specific application, hooking up a
video scaler is a simple process. The original video
source is fed into the scaler (via good quality coax),
and the output of choice (format, resolution and re-
fresh rate) comes out of it. In most cases, connection
to the display device occurs via HD-15 VGA or BNC
connectors.
Certain video wall processors provide only progres-
sive scan RGB inputs, such as computer video. For
these units, a video scaler such as Deuce may be
used to convert NTSC and PAL video to progressive
scan RGB. In addition to providing the basic, neces-
sary conversion, Deuce uses sophisticated de-inter-
lacing, motion compensation and time base correc-
tion algorithms (for stabilization), so as to provide the
highest-quality image. It then generates output that
directly matches the native resolution of the cubes, so
that the wall processor does not need to “reprocess”
the image, a step which often causes unwanted arti-
facts and scan lines. (See the CSI education guide
entitled:
Intelligent Video Scaling, A Superior Alterna-
tive to Line Doubling and Line Quadrupling.)
Another use for Deuce would be in environments
that require multiple monitor displays, such as cable
TV facilities, traffic control centers, surveillance moni-
toring, broadcast control rooms, multi-point
videoconferencing, and certain multimedia and bill-
board applications. In situations such as these, the
In cases where the scaler is connected to a fixed-
resolution display device, it is always best to select
the output that exactly matches the display device’s
“native resolution.” This corresponds to the exact num-
ber of pixels that comprise the display’s image. (i.e.
800x600 or 1024x768)
Note that this is not always
the same as the maximum resolution that the display
is able to accept.
In the case of CRT displays, how-
ever, the best quality image will result from matching
the device’s
maximum
display resolution. A good qual-
ity scaler should provide a variety of output resolu-
tions that match those used by most monitors, cubes,
projectors and panels currently on the market.
In addition, video scalers such as Deuce provide
multiple output horizontal refresh or frame rates. When
connecting to devices that will accept more than one
refresh rate, selecting the higher rate (such as 75 Hz)
will result in a brighter image with less flicker. This is
helpful for high ambient light environments.
Many video cubes offer two selectable inputs. This
allows for configurations that require the video wall
processor to provide one image to all the cubes, plus
the option of having individual video scalers provide
TwinSplit, HexiSplit and Deuce are registered trademarks of Communications Specialties, Inc.
© 1999, Communications Specialties, Inc.