High Definition Multimedia interface (hdmi) is a fully digital video and sound transmission interface that can transmit uncompressed audio and video signals. hdmi can be used for set-top boxes, DVD players, personal computers, televisions, game consoles, integrated amplifiers, digital audio and televisions and other equipment. hdmi can send audio and video signals at the same time. Because the audio and video signals use the same wire, the installation difficulty of the system line is greatly simplified.

hdmi is designed to replace older analog signal video and audio transmission interfaces such as SCART or RCA terminals. It supports various TV and computer video formats, including SDTV, HDTV video images, plus multi-channel digital audio. Both HDMI and UDI without audio transmission function inherit DVI’s core technology “Transmission Minimized Differential Signal” TMDS, which is still an extension of DVI in essence. The video content of DVI, HDMI, and UDI is transmitted in real-time and dedicated line mode, which can ensure that there will be no blockage when the video traffic is large. The amount of data per pixel is 24 bits. The signal timing is very similar to

. The picture is sent line by line, and a specific blank time (similar to an analog scan line) is added after each line and each frame picture is sent, and the data is not “Micro-Packet Architecture”. It will not only update the changed part of the two frames before and after. Each picture will be completely resent when it is updated. When the specification was first formulated, its maximum pixel transfer rate was 165Mpx/sec, which was enough to support 1080p quality at 60 frames per second, or UXGA Resolution (1600×1200); later it was expanded to 340Mpx/sec in the HDMI 1.3 specification to match future possibilities Demand.

At the beginning, DisplayPort was developed for LCD monitors and adopted the “Micro-Packet Architecture” transmission architecture. Video content is transmitted in packets. This is obviously different from DVI, HDMI and other video transmission technologies. In other words, the emergence of HDMI replaces analog signal video, and the emergence of DisplayPort replaces DVI and VGA interfaces.

HDMI also supports uncompressed 8-channel digital audio transmission (sampling rate 192kHz, data length 24bits/sample), and any compressed audio stream such as Dolby Digital or DTS, as well as the 8-channel 1bit DSD signal used by SACD. In the HDMI 1.3 specification, support for ultra-high data volume uncompressed audio streams such as Dolby TrueHD and DTS-HD has been added.

The standard Type A HDMI connector has 19 pins, and another Type B connector that supports higher Resolution is defined, but no manufacturer uses the Type B connector. The Type B connector has 29 pins, allowing it to send an extended video channel to meet future high-quality requirements, such as WQSXGA (3200×2048).

Type A HDMI is backward compatible with the Single-link DVI-D or DVI-I interface used by most displays and graphics cards today (but does not support DVI-A), which means that the signal source using the DVI-D interface can be passed through the conversion cable Drive HDMI Display, but this conversion scheme does not support audio transmission and remote control functions. In addition, if there is no HDCP certified DVI display, you will not be able to watch the video data output from HDMI with HDCP encryption protection (all HDMI displays support HDCP, but most displays with DVI interfaces do not support HDCP), Type B HDMI connector It will also be backward compatible with the Dual-link DVI interface.