The full name of HDMI is "High Definition Multimedia", namely: high-definition multimedia interface.

HDMI is pin-compatible with DVI, but in a different package. Compared to DVI. HDMI can transmit digital audio signals and adds support for HDCP while providing better DDC options. HDMI can transmit up to 15 meters, enough to handle a 1080p video and an 8-channel audio signal. HDM1 supports EDID and DDC2B. Therefore, HDMI devices have the function of “plug and play”. The “negotiation” is automatically performed between the signal source and the display device, and the most suitable video multiplier format is automatically selected. A pair of clock differentials, three pairs of data transmission differential.

The HDMI interface is divided into A, B, C, and D types. Type A is the most common type. Generally, flat panel TV or video equipment provides interfaces of this size. Type A has 19 pins, width is 13.9 mm, thickness is 4.45 mm, and devices can be seen now. 99% are HDMI interfaces of this size.

Type B is very rare, with 29 stitches and a width of 21 mm. The transmission bandwidth is almost double that of Class A. It is completely "strong" in home applications and is now only used in some professional situations.

Class C is born for small devices, and its size is 10.42 × 2.4 mm, which is nearly 1/3 smaller than Type A, and the application range is small.

Type D is the latest interface type, and its size is further reduced. It adopts a double-row pin design and is similar in size to the miniUSB interface, making it suitable for portable and in-vehicle devices.

HDMI interface is different, but the function is the same, usually the quality of the HDMI interface, plug and play life will not be less than 5000 times, can be used for 10 years per day, it should be said that it is very durable. It is also worth mentioning that HDMI can be backward compatible with DVI interface. It can be connected to some older DVI devices through the commercially available HDMI-DVI adapter. Because DVI also uses TMDS mode, DVI devices will be found after the device is connected. Without CEC (consumer electronics control) function, it can not accept audio signals, but it does not affect the transmission of video signals (it may need to be adjusted with grayscale), so some monitors with DVI only can also be connected to HDMI devices.

In addition to the different types, the HDMI interface also corresponds to different functions.

The first: HDCP 2.2, this technology protects high-value digital movies, TV shows and audio content from illegal theft and copying.

The second one: HDMI-ARC (Audio Return Channel) function, used for the output of TV digital audio, can be connected to the power amplifier that also supports ARC function, and the sound of the TV is transmitted to the power amplifier.

The third one: bit refers to the color depth, the general notebook screen is 6bit, the high-end 8bit, the special professional 10bit, can be understood as the color depth of 2 to the 10th power, and 10bit specifically refers to a video encoding technology, can provide Very high video quality, able to show extraordinary detail in the gradual change and change of color, but the configuration requirements for playing 10bit is still very high.

No. 4: MHL technology delivers up to 4K Ultra HD uncompressed video with eight channels of digital audio using only five cables while charging mobile devices.

HDMI supports EDID and DDC2B, so devices with HDMI have “plug and play” features, and “negotiation” is automatically performed between the signal source and the display device to automatically select the most appropriate video/audio format. HDMI mainly meets the needs of HDP above 1080P. For example, the motherboard or graphics card is equipped with HDMI interface. It means that the computer equipped with the motherboard or graphics card supports 1080P video output. We can connect the monitor with 1080P resolution or LCD TV to the computer and play 1080P full HD. video.

Compared with DVI, the HDMI interface is smaller, and the HDMI/DVI cable length is no more than 8 meters. As long as one HDMI cable can replace up to 13 analog transmission lines, it can effectively solve the problem of messy connection behind the home entertainment system.

Advantages of HDMI over existing analog video interfaces such as composite, S-Video, and component video:

1. Quality: HDMI is a digital interface. Since all analog connections (such as component video or S-video) require no loss when converting from analog to digital, it provides the best video quality. This difference is especially noticeable at higher resolutions, such as 1080p. Digital video will be sharper than component video, eliminating the softness and smearing found in component video. Tiny, high-contrast details such as text take this difference to the limit.

2, ease of use: HDMI integrates video and multi-channel audio in a single cable, eliminating the cost, complexity and confusion of the multiple cables used in current A/V systems. This is especially useful when upgrading or adding devices.

3, high intelligence: HDMI supports two-way communication between video sources (such as DVD players) and DTV, enabling new features, such as automatic configuration and one-click playback. By using HDMI, the device automatically transmits the most efficient format for connected displays (eg 480pvs720p, 16:9vs4:3), eliminating the need for consumers to scroll through all formatting options to guess the best viewing format.

4, high-definition content ready: HDCP-enabled HDMI devices can access advanced high-definition content, giving us some comfort. HD-DVD and Blu-ray have delayed launch image rejection tags (also known as content protection tags) for today's high-definition movies to help minimize potential problems due to conversions, but are expected to launch this tag within a few years. This means that future high-definition movies will not be able to play in high definition through unprotected interfaces such as analog components.

HDMI can be used in set-top boxes, DVD players, personal computers, video games, integrated amplifiers, digital audio and televisions. HDMI can transmit audio and video signals simultaneously.