How to define DVI in the video card

DVI's English full name is Digital Visual Interface, Chinese called "Digital Video Interface". is a kind of video interface standard, the goal of the design is to strengthen the picture quality of personal computer monitor through digital transmission. Currently widely used in LCD, digital projector and other display equipment. This standard is made up of a forum that shows several leading vendors in the industry: "Digital display Working Group" (Digital display Working group,ddwg). The DVI interface can transmit uncompressed digital video data to the display device. This specification is partially compatible with the HDMI standard.

The DVI interface protocol allows the pixel's brightness and color signals to be transmitted in binary form to the display device from the source of the signal (such as the video card). When the display device is driven by its native resolution, only the numerical data of each pixel from the DVI is read and applied to the correct position. The pixel data transmitted by analogy is affected by adjacency pixel data, electromagnetic noise and other analog distortions, in which each pixel in the output register corresponds directly to each pixel of the display. Make the picture quality has the basic safeguard.

DVI Interface Technology

The DVI interface is based on the Panallink interface technology of silicon Image company, and the Electronic Protocol of TMDS (Transition minimized differential signaling, minimized transmission difference signal) as the basic electrical connection. TMDS is a differential signaling mechanism that encodes pixel data and transmits it through a serial connection. The digital signal generated by the video card is encoded by the transmitter in accordance with the TMDS protocol and sent to the receiver via the TMDS channel, which is decoded to the digital display device.

A DVI display system consists of a transmitter and a receiver. The transmitter is the source of the signal, can be built inside the graphics chip, can also be in the form of additional chips in the graphics card PCB, and the receiver is a monitor on the circuit, it can accept digital signals, decoding and transmission to the digital display circuit, through both, the video card issued by the signal to become the image on the monitor.

DVI Interface Classification

The DVI connector also contains the foot bits of the traditional analog signal (VGA), in addition to the digital signal foot position specified in the DVI standard, designed to maintain the versatility of the DVI so that different forms of the screen can share the same connection line. The DVI connectors are divided into three types as the implementation function is different:

Dvi-d (d= Digital, only transmit digital signals): is a digital signal interface, can only go to the Dvi-d interface signal, the interface is only 3 rows 8 columns A total of 24 pins, of which the upper right corner of a pin is empty. Incompatible analog signal.

Dvi-a (a= Analog, only transmits analog signals): Analog signal interface, can only go to the DVI-A or VGA interface signal.

Dvi-i (I = A+d = integrated, teleport digit and analog signal): Contains Dvi-a and dvi-d two interfaces, which are clearly differentiated in pin definitions and can be compatible with both analog and digital signals. Compatible analog signal does not mean that analog signal interface D-sub interface can be connected to the Dvi-i interface, but must be through a conversion connector to use, the general use of this interface card will have the relevant conversion connectors.

When the dvi-i to the VGA, is played the role of Dvi-a, when Dvi-i dvi-d, only played the role of Dvi-d. In addition, the joint that is actually making the second set of DVI paths is sometimes called DVI-DL (dual link).

Some newer types of DVD players, televisions (including HDTV) and projectors use so-called "DVI/HDCP" connectors, which are identical in shape to DVI, but the data transmitted by the HDCP protocol is encrypted to prevent unauthorized copying. Today, a computer with a DVI interface card can often use the aforementioned display device as a large screen, but because most of the graphics cards produced before 2007 do not support HDCP, they may be limited by the copyright protection technology and can not play at the highest resolution of HDCP protected video content.

In addition, Dvi-d's analogy feet are deliberately designed to be shorter than the dvi-i, in order to prevent the user from mistakenly inserting the dvi-i into Dvi-d's mother seat.

The advantages of the DVI interface

Fast: DVI transmits digital signals, digital image information without any conversion, will be directly transferred to the display device, thus reducing the number → simulation → digital cumbersome conversion process, greatly saving time, so it faster, effectively eliminate the drag shadow phenomenon, and the use of DVI for data transmission, The signal does not decay, the color is more pure, more lifelike.

Clear screen: DVI interface does not need to do these transformations, to avoid the loss of signal, so that the sharpness of the image and the details of the expression have been greatly improved.

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supports the HDCP protocol: The DVI interface supports the HDCP protocol, laying the groundwork for future high-definition video viewing with copyright.