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9. Technologies
9.2. HDCP Management
Lightware Visual Engineering is a legal HDCP adopter. Several
functions have been developed which helps to solve HDCP related
problems. Complex AV systems often have both HDCP and non-HDCP
components. The matrix allows transmitting HDCP encrypted and
unencrypted signals. The devices will be still HDCP compliant as they
will never output an encrypted signal to a non-HDCP compliant display
device. If an encrypted signal is switched to a non-compliant output, a
red screen alert or muted screen will appear.
9.2.1. Protected and Unprotected Content
Many video sources send HDCP protected signal if they detect that
the sink is HDCP capable – even if the content is not copyrighted. This
can cause trouble if an HDCP capable device is connected between
the source and the display. In this case, the content cannot be viewed
on non-HDCP capable displays and interfaces like event controllers.
Rental and staging technicians often complain about certain laptops,
which are always sending HDCP encrypted signals if the receiver
device (display, matrix router, etc.) reports HDCP compliancy.
However, HDCP encryption is not required all the time e.g. computer
desktop image, certain laptops still do that. To avoid unnecessary
HDCP encryption, Lightware introduced the HDCP enabling/disabling
function: the HDCP capability can be disabled in the Lightware device.
If HDCP is disabled, the connected source will detect that the sink is
not HDCP capable, and turn off authentication.
9.2.2. Disable Unnecessary Encryption
HDCP Compliant Sink
All the devices are HDCP-compliant, no manual setting is required,
both protected and unprotected contents are transmitted and
displayed on the sink.
Encrypted
signal
SOURCE
SIGNAL
HDCP
MONITOR 1
+5V
PRESENT
ACTIVE
HOTPLUG
POWER
DVI cable
USB
CONTROL
2 OUTPUT HDCP AND HDMI1.3 COMPLIANT DISTRIBUTION AMPLIFIER
Protected
DA2DVI-HDCP-Pro
content
Not HDCP-compliant Sink 1.
Not-HDCP compliant sink is connected to the matrix. Some sources
(e.g. computers) always send HDCP encrypted signals if the receiver
device reports HDCP compliancy, however, HDCP encryption is
not required all the time (e.g. computer desktop image). If HDCP is
enabled in the matrix, the image will not be displayed on the sink.
Not HDCP-compliant Sink 2.
9.3. Pixel Accurate Reclocking
Encrypted
signal
D D A A 2 2 D D V V I I - - H H D D C C P P - - P P r r o o
MONITOR 2
EDID
PRESS
HOTPLUG
STATUS
LEARN
00: EDID COPY
DVI cable
FROM OUT 1
HDCP-compliant
sink
Intra-pair Skew
DA2DVI-HDCP-Pro – User's Manual
Non-encrypted
Non-encrypted
signal
signal
D D A A 2 2 D D V V I I - - H H D D C C P P - - P P r r o o
SOURCE
SIGNAL
HDCP
MONITOR 1
MONITOR 2
EDID
PRESS
+5V
PRESENT
ACTIVE
HOTPLUG
HOTPLUG
STATUS
LEARN
POWER
DVI cable
00: EDID COPY
DVI cable
FROM OUT 1
USB
CONTROL
2 OUTPUT HDCP AND HDMI1.3 COMPLIANT DISTRIBUTION AMPLIFIER
Unprotected
DA2DVI-HDCP-Pro
content
Setting the HDCP parameter to Auto on the output port and disable
HDCP on the input port, the transmitted signal will not be encrypted
if the content is not protected. Thus, non-HDCP compliant sinks will
display non-encrypted signal.
Encrypted
signal
D D A A 2 2 D D V V I I - - H H D D C C P P - - P P r r o o
SOURCE
SIGNAL
HDCP
MONITOR 1
MONITOR 2
EDID
PRESS
+5V
PRESENT
ACTIVE
HOTPLUG
HOTPLUG
STATUS
LEARN
POWER
DVI cable
00: EDID COPY
DVI cable
USB
FROM OUT 1
CONTROL
2 OUTPUT HDCP AND HDMI1.3 COMPLIANT DISTRIBUTION AMPLIFIER
Protected
DA2DVI-HDCP-Pro
content
The layout is the same as in the previous case: non-HDCP compliant
display device is connected to the matrix but the source would send
protected content with encryption. If HDCP is enabled on the input
port of the matrix, the source will send encrypted signal. The sink
is not HDCP compliant, thus, it will not display the video signal (but
blank/red/muted/etc. screen). If HDCP is disabled on the input port
of the matrix, the source will not send the signal. The solution is to
replace the display device to an HDCP-capable one.
Signal reclocking is an essential important procedure in digital signal
transmission. After passing the reclocking circuit, the signal becomes
stable, jitter-free, and can be transmitted over more equipment like
processors, or event controllers. Without reclocking, sparkles, noise,
and jaggies appear on the image.
Lightware's sophisticated Pixel Accurate Reclocking technology
fixes more problems than general TMDS reclocking. It removes not
only intra-pair skew but inter-pair skew as well. The Pixel Accurate
Reclocking circuit eliminates the following errors:
Skew between the + and - wires within a differential wire pair (e.g.
Data2- and Data2+). It's caused by different wire lengths or slightly
different wire construction (impedance mismatch) in DVI cable. It
results in jitter.
Non-HDCP
compliant sink
Inter-pair Skew
Skew between two differential wire pairs in a cable. It is caused by
different wire pair lengths or different number of twists in the DVI
cable. Too much inter-pair skew results color shift in the picture or
sync loss.
Non-HDCP
compliant sink
Jitter
Signal instability in the time domain. The time difference between two
signal transitions should be a fixed value, but noise and other effects
cause variations.
Noise
Electromagnetic interference between other electronic devices such
as mobile phones, motors, etc. and the DVI cable are coupled onto the
signal. Too much noise results in increased jitter.
27
+
-
Intra-pair skew
+
-
+
-
Inter-pair skew
+
-
Jitter
+
-
Noise
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