High Definition Multimedia Interface (HDMI) is a fully digital video and sound sending interface that can send uncompressed audio and video signals. HDMI can be used in 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. Since audio and video signals use the same wire, it greatly simplifies the installation of system lines.
HDMI is designed to replace older analog signal audio and video sending interfaces such as SCART or RCA terminals. It supports various TV and computer video formats, including SDTV and HDTV video images, plus multi-channel digital audio. Both HDMI and UDI without the audio transmission function inherit DVI's core technology "Transmission Minimized Differential Signal" TMDS, which is still essentially an extension of DVI. DVI, HDMI, and UDI video content are all transmitted in real-time and through dedicated lines, which ensures that no congestion will occur when video traffic is large. The amount of data per pixel is 24 bits. The timing of the signal is very similar to VGA. The picture is sent line by line, and a specific blank time is added after each line and frame of the picture is sent (similar to an analog scan line), and the data is not "Micro-Packet Architecture" transformation, it will not update only the changed parts of the two frames before and after. Each frame will be completely resent during this update. 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 (1600x1200); it was later expanded to 340Mpx/sec in the HDMI 1.3 specification to match future possibilities. needs.
DisplayPort was initially developed for LCD displays, using the "Micro-Packet Architecture" transmission architecture. Video content is transmitted in packets, which is significantly different from video transmission technologies such as DVI and HDMI. In other words, the emergence of HDMI replaced analog signal video, while the emergence of DisplayPort replaced DVI and VGA interfaces.
HDMI also supports uncompressed 8-channel digital audio transmission (sampling rate 192kHz, data length 24bits/sample), as well as any compressed audio stream such as Dolby Digital or DTS, and also supports 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 a Type B connector that supports higher resolutions has been defined, but no manufacturer has yet used the Type B connector. The Type B connector has 29 pins, allowing it to send extended video channels to meet future high-quality requirements, such as WQSXGA (3200x2048).
Type A HDMI is backward compatible with the Single-link DVI-D or DVI-I interface used by most monitors and graphics cards today (but does not support DVI-A). This means that signal sources using the DVI-D interface can be used through the conversion cable Drives HDMI display, but this conversion solution does not support audio transmission and remote control functions. In addition, DVI displays without HDCP certification will not be able to watch 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 Dual-link DVI interface.