Displayport Testing: Ensuring Compatibility For Consumers

DisplayPort is an audio-video interconnect standard that is designed to advance display simplicity and the adoption of protected digital outputs on computers. This allows users to easily view HD content and other protected files. Because DisplayPort signaling can transmit both DVI and HDMI signals (other digital display protocols), the technology is compatible with many popular interconnects and subsequently, the consumer devices that use the standards. For consumers, this means they can easily incorporate DP sources or devices in their homes and offices.

The DisplayPort interface standard, defined by the Video Electronics Standards Association (VESA), an organization that promotes standardization in the display segment, is a digital audio/video interconnect for computers, monitors and home-theater systems. The organization also determines standard sizes for flat panel display mounts in addition to other standardization efforts. Formally approved in 2006, the interface includes DisplayPort Content Protection (DPCP). This content protection capability uses 128-bit encryption and features full authentication and session key establishment. For consumers, this means that even commercially protected content will play back over the interface, ensuring a seamless user experience.

DisplayPort Version 1.1 added support for high-bandwidth digital content protection (HDCP) to prevent copying of digital audio and video content as it travels across DP connections to a display device. HDCP is also used in other types of connections, such as HDMI.

PC manufacturers developed the interface to address computing concerns and replace the external analog video graphics array (VGA) interfaces in PC and LCD monitors and in consumer electronics equipment. Additionally, the technology offers additional capabilities over external digital visual interface (DVI) connectors found in devices. It also aims to replace internal, board-to-display low voltage differential signaling (LVDS) links in devices with a unified link interface.

This technology appears to be gaining momentum. According to a 2008 report from industry analyst firm In-Stat; DisplayPort is predicted to reach the milestone of more than 600 million products shipped by 2012. The web site lists more than 165 members of VESA, a veritable who's who of the consumer electrics and PC industries. Many of these companies have announced their intention to implement or support the technology into their products. Some notable industry heavyweights, like Dell, for example, already have numerous displays shipping with the technology.

MINI DISPLAYPORT - APPLE DRIVES SMALLER FORM FACTOR
The Mini DisplayPort interface is a smaller version of the traditional plug and connector, and was first publicly announced by Apple in 2008. Apple products featuring the Mini connector include the MacBook family of laptops, the iMac, Mac Mini, Mac Pro and the entire Apple Cinema line of displays. DisplayPort replaced the DVI and mini-DVI interfaces found on previous generations of Macs. The user-friendly Mini connector links the Mac to an LED Display, and offers both video and audio support, reducing the number of cables associated with incorporating an external display and speakers.

Unlike Mini-DVI and Micro-DVI predecessors, the Mini DisplayPort is capable of displaying the high resolutions commonly associated with 30 inch and larger displays. Large displays are becoming more common. Integrators Dell and Apple recently released 30 inch product offerings. Laptops with a Mini can connect a computer to an external display or projector with a VGA or DVI interface by using an adapter. While the mini and regular DisplayPort signals are identical, their connectors are different.

In early 2009, VESA announced that it would include Mini DisplayPort in the DisplayPort 1.2 specification. The 1.2 specification is anticipated to be finalized by VESA by the end of this year. The specification offers features including:

--- 2X the speed of the 1.1a specification
--- Multiple stream support over one connector
--- Optional higher speed auxiliary channel which enables bi-directional bulk data transfer over one cable
--- Additional support for the Mini-connector
--- Backward compatibility with version 1.1a

DISPLAYPORT TESTING
Working with an independent test lab accredited by VESA to perform DisplayPort testing helps ensure that Display Port products will function properly, which is especially essential with consumer video applications. The compliance and logo program testing guarantees that products will comply with developed standard guidelines.

DisplayPort test categories include:

--- Physical Layer Test
--- Link Layer Test
--- Electrical Test
--- HDCP Test

While VESA does not require certification of DisplayPort products, it is highly encouraged. Once a manufacturer's device is certified, the manufacturer obtains the right to use the logo. The DisplayPort Certified Logo reassures end users that certified products will interoperate properly and provide a quality digital display experience.

RELATED TESTS
Tests related to the DisplayPort test include:

--- HDMI Compliance Test: The HDMI compliance test ensures High Definition Multimedia Interface (HDMI) products will function properly.
--- Consumer Electronics Control Test (CEC test): CEC is one of the functions defined within the HDMI specification 1.2a. This test verifies that the CEC function of a product will perform correctly.
--- HDCP Compliance Test for HDMI or DisplayPort products: This test determines whether or not HDCP implementation meets certain specific requirement.
--- sRGB Compliance Program: Products that pass all sRGB tests will be granted use of the sRGB logo. This logo shows end users that the display has been tested by an independent third-party test lab.