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The DisplayPort Information Guide

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An Introduction to the DisplayPort Interface





WHAT IS THE DISPLAYPORT CONNECTOR?

DisplayPort is the newest digital video interface connect, designed as a replacement for the DVI standard currently in use on computer hardware. It is similar in specification to the HDMI standard, but unlike HDMI, DisplayPort is being targeted as a computer-interface more than a home-theater-interface.

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.
Unfortunately, DisplayPort and DVI use fundamentally different signal processing methods, so adapting between the two cannot be done with a simple adaptor or cable (in most circumstances). DVI, like VGA and HDMI, uses separate data channels for each color, requiring a high bandwidth at all times. DisplayPort renders the entire image and breaks it into packets, and these are transferred to the display much like network data over an ethernet line. Some DisplayPort ports are built to be compatible with DVI internally, and can be adapted passively, but this is not a requirement of the DisplayPort standard. In these situations it will appear as though the Displayport is being "converted" to DVI, but it's actually the hardware outputting a DVI signal through a Displayport connector. If the hardware in use is not capable of outputting this DVI signal, then a Displayport-to-DVI adaptor will not function properly.

HOW DOES DISPLAYPORT COMPARE TO HDMI?

While HDMI is the digital standard targeted towards home theaters and Displayport targeted towards computer electronics, 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.

Because DisplayPort has a newer release schedule than HDMI, it does outperform in a handful of specifications:

  • 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 manufacturers and consumers

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 somewhat compatible. DisplayPort uses a signal technology entirely different from DVI/HDMI, and is not natively compatible. However, some DisplayPort hardware has built-in convertors to a DVI-compatible format, so a passive DVI/HDMI adaptor will function properly. If the DisplayPort does not have this feature, then external electronic conversion will be necessary.

HDMI and DisplayPort - DVI and HDMI use the same signal technology, so HDMI suffers the same incompatibility with DisplayPort, and likewise the same possibility for conversion. If the DisplayPort hardware has built-in adaption, then a DisplayPort-to-HDMI cable or adapter will function perfectly. If not, then an external HDMI-DisplayPort convertor will be necessary.


WHERE IS DISPLAYPORT AVAILABLE?

Since 2008, DisplayPort has been slowly integrated into consumer electronics and can be found on most high-end flatpanel displays and modern video cards. Consistent with its emphasis on the computer market, DisplayPort is less commonly found on Blu-Ray players and set-top boxes, although such can be found.

Written by Anthony van Winkle for DataPro International Inc.
Unauthorized duplication strictly prohibited.

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