DisplayPort is a digital video interface standard promoted by the Video Electronics Standards Association, scheduled for May 2006.The interface is a new digital audio/video interface that is designed to connect a computer to a screen, or a computer to a home theater system, with no certification and no licensing fees.It is intended to replace the older VGA, DVI and FPD-Link(LVDS) video transfer interface technologies.
DisplayPort was the first display interface to rely on the packet-enabled data transfer technology found in Ethernet, USB, and PCI Express.It can be used for both internal and external display connections.Unlike past standards, which required the clock signal to be transmitted in a fixed differential pair at each outlet, the DisplayPort protocol is based on small packets called micropackets that can embed the clock signal in the data stream.The advantage is that with fewer pins, higher resolution can be achieved.The application of packets also allows the use of DisplayPort to be extensible, which means that the physical interface itself can be added with additional functionality without significant changes over time.
DisplayPort can be used to transmit audio and video at the same time, each of which can be transmitted separately without the other.Each color channel in the video signal path can have 6 to 16 bits, and the audio path can have up to 8 channels of 24-bit 192 kHz uncompressed PCM audio, or compressed audio formats that can be encapsulated in the audio stream.A bi-directional, half-duplex secondary channel carries device management and device control data for the main link, such as VESA EDID, MCCS and DPMS standards.In addition, the interface is capable of delivering bidirectional USB signals.
DisplayPort signals are not compatible with DVI or HDMI.However, dual-mode DisplayPorts are designed to transmit single-link DVI or HDMI 1.2/1.4 protocols over this interface, requiring the use of an external passive adapter to select the desired signal and convert the electrical signal from LVDS to TMDS.Dual mode DisplayPorts with passive adapters do not support VGA and dual link DVI.These interfaces require active adapters to convert the desired output protocols and signals.VGA adapters can be powered using the DisplayPort connector, while dual-link DVI adapters may rely on an external power supply (see HDMI, DVI, and VGA compatibility).
The DisplayPort connector can have 1,2, or 4 channel differential data pairs (laneways) on the main link, each laneway can have a raw bit rate of 1.62, 2.7, or 5.4 Gbit/s based on the clock running at 162, 270, or 540MHz.The data is 8B / 10B encoded, that is, every 8 bits of information is encoded in a 10 bit symbol.Thus, the effective data transfer rate per channel after decoding is 1.296, 2.16, 4.32 Gbit/s (or 80% of the total volume).