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September 2014
Issue: January 1, 2009

DISPLAYPORT POSITIONED AS NEXT-GEN INTERFACE

By: Roger Quero
The availability of lower cost, high resolution LCD panels is becoming more and more important in delivering enhanced image quality for professionals, enthusiast gamers and casual users alike. As panel resolution and color depth increase, the bandwidth required to drive these panels also increases; hence the need for a new display interface.

DisplayPort is the next generation digital display interface, designed to move the industry forward to new and innovative display capabilities. This new standard could be implemented ubiquitously, providing a universal display interface for internal display connections (for notebooks and all-in-one PCs), and external display connections between a PC and a monitor or projector.

Several companies in the PC industry recognized the need for a more flexible standard that would provide greater bandwidth to support more features and new capabilities. With this bandwidth, a video card with a DisplayPort interface can drive a 30-bit LCD panel to display over one billion colors. Other features of DisplayPort include simpler cabling and connectivity, and compatibility with other display interfaces.

Intended to replace DVI and eventually VGA, DisplayPort was designed to support higher resolutions, color depths and refresh rates. Unlike the DVI standard, DisplayPort is a living specification that is expected to continue to evolve over time. DisplayPort is supported by more than 180 member companies of VESA (the Video Electronics Standards Association) and was created by many of the PC industry's top companies, including AMD, Apple, Dell, HP, Genesis (Now ST Microelectronics), Nvidia and Samsung.

Greater Bandwidth

The DisplayPort link consists of a main link, an Aux channel and a Hot Plug Detect signal line. The audio and video streams are transported over the main link, which can be configured to support 1, 2, or 4 lanes, each with a transfer rate of 1.62 or 2.7 gigabits/sec. This equates to a maximum of 10.8 gigabits/second of bandwidth, which is more than twice the raw bandwidth of a single link DVI interface.  In addition to having superior bandwidth, DisplayPort was designed to allow flexible use of that bandwidth. As a result, monitor manufacturers can choose to offer higher resolutions, faster refresh rates or higher color depths, or any combination of the three.

More Than One Billion Colors

DisplayPort helps to solve a longstanding problem for animation, video and film professionals, who often are forced to choose between color accuracy and the affordability. Most professionals today use 24-bit displays with a range of 16.7 million colors. To obtain more accurate and precise colors, a 30-bit monitor or display is required. A few specialist monitors are available in the market today, such as grayscale displays featuring dual-link DVI that are largely used in the medical industry, and custom displays used by the movie industry. However, DisplayPort provides a simpler and more cost effective way to drive 30-bit displays.

PC and monitor manufacturers are expected to ship 30-bit displays in 2008 and 2009.  A few manufacturers have already started producing high-grade 30-bit panels for digital video pros. Developed in close collaboration with DreamWorks Animation, the HP DreamColor LP2480ZX professional LCD display features DisplayPort 1.1 video input and offers a range of more than one billion colors.

Using a video card that can process and output 10-bit color through DisplayPort and HP's DreamColor display, post pros won't have to worry about loss of color precision and accuracy. For example, digital video or images captured in 10-bit color can be viewed and edited on a 30-bit display, ensuring that the colors professionals see on the screen are consistent with the original content. For post, the HP DreamColor display delivers high precision color at a fraction of the cost of older 30-bit monitors, which could cost as much as $25,000. HP's 30-bit panel delivers true color at a suggested retail price of less than $3,600. 

Connectivity


Using a compact USB-sized connector design, DisplayPort provides seamless connectivity between monitors, projectors, and other display devices to desktop PCs and notebooks. The connector used in DisplayPort cables and sink/source devices provides greater reliability than the traditional connectors of legacy interfaces with fragile pins. In addition, DisplayPort connectors are equipped with an optional latching mechanism, which can prevent unintentional disconnects.

The DisplayPort spec also allows for longer cables than VGA and DVI. Cables can reach 15 meters in length and beyond, making it easy to connect your PC to a monitor or a projector across the room. As the standard evolves, it is expected to allow single cable connectivity between a PC and peripherals such as the display, mouse and keyboard. Additionally, the next-gen DisplayPort is expected to allow multiple displays to be connected to a PC through a single cable.

Backwards compatibility is an important feature of DisplayPort.  DisplayPort multimode source and sink devices can support DVI and HDMI signals. To connect a PC equipped with a DisplayPort multimode video card to an older monitor or an HDTV, users only need to attach a DisplayPort to DVI (or HDMI) adapter. DisplayPort to VGA adapters are also available for older LCD panels and CRT monitors.

Conclusion

Recent advances in the development of DisplayPort source and sink devices suggests that DisplayPort will become a standard feature on many PCs and display devices within one to two years. Moreover, widespread adoption of this technology is expected to push the industry towards even more innovative display capabilities, ultimately affording users a superior and vivid display experience.

Roger Quero is Technical Marketing Manager with Advanced Micro Devices, Inc. (www.amd.com.)