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HOME REVIEWS CONTACT ABOUT March 14,
2009
GrandTec USB to HDMI Adapter
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You've
probably seen a coworker or colleague using multiple LCD monitors at their
computer workstation. Research at the
A
new USB-HDMI adapter module has been introduced recently that should help. The
Grandtec Electronic "Grand HD Cinema" (GHD-2000) adapts a USB port
for use as an output for up to 6 monitors (4 for Mac). This is also an easy way to implement an HDTV
adapter for a laptop computer. This module is about the size of an AC adapter
power supply for a laptop computer. What
makes this product different than its competitors is the integrated circuit
chips and software drivers, the "Display Link" technology.
Display Link Technology
The
critical chips used are made by a company called DisplayLink (formerly Newnham
Technology, website: displaylink.com).
The company is headquartered in
DisplayLink
technology supports 32-bit color at all resolutions. Whenever native resolution
can be detected, DisplayLink will display the native resolution of the screen
automatically. The video output format
is capable of high definition (720p), and audio functions for a single channel
are also integrated. DisplayLink also
provides much of the software for automatically configuring the video adapter
and the USB port.
DisplayLink
compresses the video signal for transport over the USB link to improve
bandwidth. Video signals, especially
HDTV signals, when uncompressed, require enormous bandwidth. If the original signal source is encoded
video (see MPEG) then the computer must first decode the signal. Then the
DisplayLink software driver must compress the signal using the proprietary
DisplayLink video compression codec.
This is basically transcoding, which is one of the reasons that the
computer requirements are significant.
The compressed signal is then sent over the USB link to the adapter.
Once
the signal is past the USB link, the converter uncompresses the signal for
broadcast over the HDMI link. HDMI is
capable of communicating uncompressed HDTV signals.
There
is some misleading information on-line that claims that this product is HDCP
capable, which implies that the system is amongst other things, BluRay DVD
compatible. Currently DisplayLink
technology is not HDCP compliant, since DisplayLink’s compression codec cannot
manipulate encrypted packages.
Fast
moving images may stress the capability of this technology because of the
throughput limitations of USB 2.0.
Computer Requirements
The
minimum computer requirements for this application are an XP or
Power
for the converter is supplied from the USB port, so an AC power supply is not
required.
Video Wall
It
is possible to implement a "video wall" with up to 6 displays, but only
a single audio channel can be used. Each
screen's picture can be independently rotated in increments of 90 degrees.
The
system supports extended desktop video (a single image split over multiple
monitors) or mirror imaging (the same image displayed on multiple
monitors). A separate USB-HDMI adapter
module will be required for each monitor in extended desktop mode.
With
multiple USB-HDMI adapters, each monitor can show separate programming. The limitation will be the computers ability
to encode each channel because the process is computation intensive.
Many people now use their computers to watch
television and movies. There is a need
to be able to easily view the computer's signal on a larger HDTV. The Grandtec
Electronic Grand HD Cinema is well suited for this purpose. The Grand HD Cinema currently sells on-line
for $130-$150.