Thread: Displayport

Approved in May 2006, Displayport was designed by the Video Electronics Standards Association (Vesa) as a future-proof multimedia interface. It has solid support from AMD/ATI, Nvidia and Dell, among others, and is due in AMD motherboards this year.

Like HDMI, Displayport supports both video and audio in high definition. Displayport has some advantages over HDMI. It can run at its full bandwidth - up to 2,560xl,600 at 60Hz with 30-bit colour - using cables up to 3m in length. It can also transmit at resolutions of up to 1080p over cables stretching up to 15m from the source. And it can support up to eight channels of audio, and synchronise between video and audio to within Ims accuracy.



Displayport can be used for both external and internal connections, giving compatibility between components and devices and simplifying manufacturing processes. It will be possible to build TFT monitors using panels that use Displayport natively, avoiding the need for complex circuitry in the monitor. The external connector is designed to be compact, allowing up to four connections on a single full-height PCI bracket.

Unlike other proposed standards, Displayport offers no easy interoperability with HDMI or DVI, and uses entirely different signalling methods. While such a lack of compatibility may be a disadvantage, Displayport's Micro-Packet architecture allows great flexibility. You can transmit picture-in¬picture streams over a single cable, and displays can be daisy-chained from a single connector. Up to six 1080i or three 1080p streams can be connected in this way. Displayport also has advanced two-way communication capabilities, including bi-directional audio for applications such as VoIP and audio chat. There's also a low-bandwidth video back-channel that's ideal for webcam use.

Displayport supports optional content protection, but as standard it uses its own Displayport Content Protection (DPCP) scheme, rather than the well¬established HDCP, though version 1.1 of Displayport adds the option for HDCP. Both of these content¬protection schemes require separate licence fees, potentially increasing the end-user price of Displayport -enabled equipment, especially if they're both implemented.

Although the Displayport spec doesn't include backward-compatibility with HDMI or DVI sources, it's possible to use both of these standards via the physical Displayport connector. Not all Displayport¬compatible devices will be able to do this and those that can will sport 'multimode' logos.

In the early days of Displayport, Vesa expects the PC market to drive demand for the interface, while consumer electronics products stick to HDMI. However, given the increasing number of HDMI¬enabled PC graphics cards and motherboards, it remains to be seen whether PC users can be shifted so soon onto yet another interface.