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| DataPro Tech Info > The DisplayPort Information Guide |
The DisplayPort Information Guide |
An Introduction to the DisplayPort Interface
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WHAT IS THE DISPLAYPORT CONNECTOR?
DisplayPort is (yet another) new digital video interface connect,
recently finalized by the Video Electronics Standards Association (VESA).
The DisplayPort standard is being pitched as the newest replacement
for the analog VGA and digital DVI standards currently in use on computer
hardware. It is similar in specification to the also-new HDMI standard, but
unlike HDMI, DisplayPort is being targeted as a computer-interface more than
a home-theater-interface.
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HOW IS THE DISPLAYPORT DIFFERENT FROM VGA AND DVI?
While VGA has served the computer industry well for many years, its
analog-based signals (frequency-modulated red, green, and blue components)
are a weakness in fidelity. The digitally-rendered signal must be converted
to analog by the video card, which adds inconsistencies and blending, and
identical source images can vary greatly on different displays, depending on
the displays' subjective calibrations.
DVI and DisplayPort are both digital-only signals, which ensures that the
final image displayed is identical to the image rendered by the computing
hardware. Excluding DVI's existing dominance in the market, DisplayPort
has a number of advantages over its predecessor:
- The DisplayPort connector is small and screwless, for easier
installation, and added usability in space-conscious hardware
- DVI offers no audio support; DisplayPort offers full digital audio
support (up to eight channels) in the same cable as video
- DVI is crippled by its maximum spec length of 5 meters, while
DisplayPort is designed for up to 15 meters.
Fortunately, DisplayPort and DVI use the same fundamental signal processing
method, so adapting between the two can be done with a simple adaptor or
cable rather than expensive electronics.
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HOW DOES DISPLAYPORT COMPARE TO HDMI?
It seems like every other week a new "interface of the future" is released,
and DisplayPort is no exception. Hot off the heels of HDMI (the so called
"DVI replacement"), DisplayPort touts a feature-list virtually identical to
HDMI. In fact, the DisplayPort 1.1 standard was adjusted to specifically
include the HDCP content-protection standard, to improve compatibility with
HDMI.
So the question remains, why do we need another interface standard? How is
DisplayPort any better than HDMI?
- It has a maximum bandwith of 10.8 Gbit/sec, compared to HDMI at 10.2
Gbit/sec
- It supports the DPCP (DisplayPort Content Protection) standard in
addition to HDCP
- It is an open standard, available to all manufacturers at no cost; HDMI
is licensed by HDMI LLC, which raises the cost to consumers
Do these three "features" really give DisplayPort the edge? Being an open
standard is definitely a good attribute, but the bandwidth support
difference is negligible and "content protection" just makes more devices
incompatible with each other.
In the end, it will be up to the consumers to decide whether to buy into
this latest "holy grail" of display interconnects. For the time being, HDMI
is still the most popular new kid on the scene.
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IS DISPLAYPORT COMPATIBLE WITH VGA, DVI, AND HDMI?
VGA and DisplayPort - Unfortunately VGA supports only analog-based
signals, and DisplayPort only digital-based. A conversion from VGA to
DisplayPort (or vice versa) will require an electronic convertor, much like
today's VGA to DVI-D units.
DVI and DisplayPort - Aside from DVI's lack of audio support, the two
interfaces are fairly compatible. If all goes as planned, consumers will be
able to convert from DVI to DisplayPort with a simple adaptor, or use a
DVI-to-DisplayPort cable. Expect to see audio-injectors in the near future
as well.
HDMI and DisplayPort - These interfaces are so similar, it's
ridiculous. DisplayPort 1.1 was released to be fully compatible with HDMI
1.3; there is little-to-no difference between the two. Consumers will be
able to purchase simple HDMI adaptors for DisplayPort hardware, or can make
use of HDMI-to-DisplayPort cables.
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WHEN WILL THE DISPLAYPORT BE AVAILABLE?
The DisplayPort 1.1 was announced at the Consumer Electronics Show
in January of 2007, and the standard was finalized and approved by VESA on
April 2nd. Given the general industry production ramp-up time, consumers
should expect to see DisplayPorts on high-end hardware by the end of the year,
and gradually on more and more mid-range electronics throughout 2008.
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Written by Anthony van Winkle
for DataPro International Inc.
Unauthorized duplication strictly prohibited.
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