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Education | Distribution Components
5 common video errors and how to fix them.
Digital HDMI and DVI formats provide sharp, crystal-clear image
quality. However, problems can occur. Here are the five most
common:
Problem 1:
Black screen (no picture at all).
Possible cause:
A. Bad cable or cable that’s too long,
causing either the video signals or
EDID/HDCP control signals not to
be transmitted properly.
Make sure that you use quality,
high-speed HDMI
®
cables—they don’t even have to be expensive
ones—or try an HDMI extender.
B. HDCP is unsupported. Does the display support HDCP?
DVI displays usually don’t.
Problem 2:
“
Sparkles” in the picture.
Usually caused by: HDMI cable that’s
too long or of inferior grade. The
solution is to use a video extender,
and/or buy quality HDMI cables from
a reputable supplier.
Problem 3:
RGB color tint.
Usually caused by: A color encoding
issue, a common problem when using
a DVI display with an HDMI source. If
you’re using a splitter or an extender
between your source and the link,
make sure it handles EDID. If possible,
force the source (for instance, a Blu-ray player) to output HDMI video
with RGB color encoding instead of Component (YPbCr) video encoding.
Problem 4:
White noise or “snow” on-screen.
Usually caused by: An HDCP issue.
This is actually what the encrypted
video looks like. It happens when your
display (or any active component, like
an extender, used in the transmission)
doesn’t support HDCP. The display, in
turn, isn’t able to decrypt the video stream. Be sure to use equipment
that supports HDCP.
Problem 5:
Flickering or unstable image.
Can be caused by: Electromagnetic
or radio frequency interference, bad
cable, or cable that’s too long. These
all can cause issues with HDCP or the
signal, resulting in flickering or the
video randomly disappearing then
reappearing after a second.
The solution: Use certified high-speed HDMI cables instead of
standard HDMI cables, or if you need to go long distances, try
an extender. If you’re already using an extender, try changing
to shielded CAT6 solid-core bulk cable.
For more troubleshooting products, go to black-box.de
Security, Optimization,
and Troubleshooting
irewalls/data security equipment
To ensure data privacy, work with your IT department to
implement protection and safeguard your content. This is
particularly important if you’re using your AV distribution system
to send video across a hospital or government network and if you
have to comply with HIPAA, HITECH, PCI, or other data-protection
standards
This may require establishing IPsec VPN tunnels between sites. Newer
technologies, however, enable you to establish an instant encrypted
connection between locations without the administrative hassle of setting
up a separate tunnel for each link. What’s more, these technologies don’t
add latency, which can bog down your video and data communications.
Skew compensators
Some video extenders are not designed to transmit video across cable
that’s higher than CAT5. In fact, with these extenders, the higher-grade
cable may actually degrade video. The problem is with the cable twists of
CAT5e and CAT6 cables; the wire distance that a signal has to travel is
different for each pair. This doesn’t normally cause a problem with data,
but if you’re sending higher-resolution VGA analog video signals across
long cables, you may see color separation caused by the signals arriving at
different times. If the extender you’re using doesn’t have built-in skew
compensation, the remedy is a device that compensates for skew. (NOTE:
This applies only to VGA analog signals and not to digital HDMI and DVI
signals.)
Pattern generators
Use these to ensure video signal
reproduction and display are up to
par in your AV and digital signage
applications. They enable you to generate
test patterns to troubleshoot video
calibration issues. Pattern generators are
particularly useful for testing in
applications where accurate video
reproduction is important, such
as healthcare, biotech, educational,
and industrial settings.
Cable testers
In addition to pattern generators, you can
ensure a quality video infrastructure by
troubleshooting supporting cable runs.
With one of these handheld
testers, you can spot slow cables, bad
connectors, incorrect wiring, improper
lengths, and low signal levels from
switches, PCs, and other hardware
in your AV network. If you have a
qualification tester, you can also test
for available bandwidth and distinguish
between network and cable problems.
F