Digital Visual Interface

Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a display controller to a display device, such as a computer monitor. It was developed with the intention of creating an industry standard for the transfer of digital video content.

The interface is designed to transmit uncompressed digital video and can be configured to support multiple modes such as DVI-D (digital only), DVI-A (analog only), or DVI-I (digital and analog). Featuring support for analog connections, the DVI specification is compatible with the VGA interface. This compatibility, along with other advantages, led to its widespread acceptance over competing digital display standards Plug and Display (P&D) and Digital Flat Panel (DFP). Although DVI is predominantly associated with computers, it is sometimes used in other consumer electronics such as television sets, video game consoles and DVD players.

Technical overview

DVI's digital video transmission format is based on PanelLink, a serial format developed by Silicon Image that utilizes a high-speed serial link called transition minimized differential signaling (TMDS). Like modern analog VGA connectors, the DVI connector includes pins for the display data channel (DDC). A newer version of DDC called DDC2 allows the graphics adapter to read the monitor's extended display identification data (EDID). If a display supports both analog and digital signals in one DVI-I input, each input method can host a distinct EDID. Since the DDC can only support one EDID, there can be a problem if both the digital and analog inputs in the DVI-I port detect activity. It is up to the display to choose which EDID to send.

When a source and display are connected, the source first queries the display's capabilities by reading the monitor EDID block over an I²C link. The EDID block contains the display's identification, color characteristics (such as gamma level), and table of supported video modes. The table can designate a preferred mode or native resolution. Each mode is a set of CRT timing values that define the duration and frequency of the horizontal/vertical sync, the positioning of the active display area, the horizontal resolution, vertical resolution, and refresh rate.