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Section 3. Technologies
3.2. Advanced EDID management
Each DVI sink (e.g. monitors, projectors, plasma displays, and switcher inputs) must
support the EDID data structure. Source BIOS and operating systems are likely to query
the sink using DDC2B protocol to determine what pixel formats and interface are supported.
DVI standard makes use of EDID data structure for the identification of the monitor type
and capabilities. Most DVI sources (VGA cards, set top boxes, etc.) will output DVI signal
after accepting the connected sink’s EDID information. In case of EDID readout failure or
missing EDID, the source will not output DVI video signal.
MODEX transmitters
provide Lightware’s Advanced EDID Management function that helps
system integration. The transmitter’s built-in EDID memory stores and emulates more than
100 EDID data (factory presets and user memory, the exact number depends on the
firmware) plus the monitor's EDID that is connected to the
receiver’s output connector.
MODEX stores the EDID of the attached monitor or projector in a non-volatile memory.
This way the EDID from a monitor is available when the monitor is unplugged, or switched
off.
The EDID emulated on the DVI input can be copied from the transmitter's memory (static
EDID emulation), or from the last attached monitors memory (dynamic EDID emulation).
For example, the transmitter can be set up to emulate a device, which is connected to the
receiver’s DVI output. In this case the EDID automatically changes, if the monitor is
replaced with another display device (as long as it has a valid EDID).
Advanced EDID management can be controlled
by the front panel’s control buttons and via
the built-in webpage.
Info: The user is not required to disconnect the DVI cable to change an EDID as opposed to
other manufacturer’s products. EDID can be changed even if source is connected to the
input and powered ON.
Info: When EDID has been changed, the transmitter toggles the HOTPLUG signal for 2 seconds.
Some sources do not observe this signal, so in this case the change is not recognized by
the source. In such cases the source device must be restarted or powered OFF and ON
again.
3.3. HDCP management
Lightware Visual Engineering is a legal HDCP adopter, and has developed several
functions that helps to solve HDCP related problems. Complex AV systems often have both
HDCP and non-HDCP components. MODEX extenders allow to transmit 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 should
be switched to a non-compliant output, it will show a red screen alert or will be muted.
3.3.1. 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 a HDCP capable
device (e.g. an extender-pair) is connected between the source and the display. In this
case the content can’t be viewed on non-HDCP capable displays and interfaces like event
controllers.
Rental and staging technicians often complain about Apple laptops, who always send
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) MacBook and MacBook Pro still do that.
To avoid unnecessary HDCP encryption, Lightware
introduced the HDCP
enabling/disabling function: the HDCP capability can be disabled on the extenders. If
HDCP is disabled, the connected source will detect that the sink is not HDCP capable, and
turn off authentication. The source will not be able to communicate with any of the devices
(displays, repeaters, etc.) that are connected to the receiver’s output, therefore it could not
see if they are HDCP capable or not.