The full English name of HDMI is "High? Definition Multimedia", which means high definition multimedia interface in Chinese. HDMI interface can provide data transmission bandwidth up to 5 Gbps, and can transmit uncompressed audio signal and high resolution video signal. At the same time, there is no need for digital/analog or analog/digital conversion before signal transmission, which can ensure the highest quality of audio and video signal transmission.The advantage of using HDMI is that only one HDMI line can transmit audio and video signals at the same time, unlike the need for multiple wires to connect at present; at the same time, due to the wireless digital/analog or analog/digital conversion, higher audio and video transmission quality can be achieved. For consumers, HDMI technology can not only provide clear picture quality, but also greatly simplify the installation of home cinema system because of the same audio/video cable.

　　In April 2002, seven companies, Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson and Toshiba, established HDMI organizations and began to develop new standards for digital video/audio transmission. At the end of 2002, the HDMI 1.0 standard of High-definition Digital Multimedia Interface was promulgated. By the end of 2006, version 1.3 has been issued. The main change is to further increase the bandwidth in order to transmit higher resolution and color depth.HDMI is compatible with DVI on pins, but uses different packages. Compared with DVI, HDMI can transmit digital audio signals, increase support for HDCP, and provide better DDC optional functions. HDMI supports 5 Gbps data transmission rate, up to 15 meters, enough to handle a 1080p video and an 8-channel audio signal. Because a 1080p video and an 8-channel audio signal require less than 4 GB/s, HDMI still has a lot of room.HD allows it to connect DVD players, receivers and PRRs with a single cable. In addition, HDMI supports EDID and DDC2B, so HDMI devices have the characteristics of plug-and-play. There will be automatic "negotiation" between signal sources and display devices to automatically select the most appropriate video/audio format.The HDMI interface supports the HDCP protocol and lays the foundation for watching copyrighted HD movies and TV. However, in order to make graphics cards with HDMI interface, besides the need for dedicated chips, graphics cards manufacturers also have to pay a high fee for HDMI authentication, so there are not many graphics cards with HDMI interface at present. But HDCP is a foregone conclusion, so there will be more graphics cards supporting HDCP protocol in the future.