Nowadays, in the computer, the VGA analog interface and the DVI digital interface are gradually eliminated, and the high-definition HDMI has become the current mainstream video interface. So what is an HDMI interface? what's it for? What versions are there? How many types are there? What are the pins of the HDMI interface? With many questions, the editor of Dite Electronics will give you a detailed introduction.
The concept of HDMI interface
HDMI is the English abbreviation of (High Definition Multimedia Interface), which means high-definition multimedia interface. It is a digital video/audio interface technology that can transmit video and audio signals at the same time. The maximum data transmission speed is 48Gbps (version 2.1), At present, HDMI high-definition video interface is very common. At present, mainstream graphics cards, motherboards, notebooks, LCD TVs, etc. all have HDMI interfaces, which are unmatched by ordinary VGA display interfaces. Just like broadband telephone lines and optical fibers in broadband, the ability to transmit data is relatively high. big difference.
The role of HDMI interface
HDMI mainly meets the needs of high-definition video above 1080P. For example, the motherboard or graphics card is equipped with an HDMI interface, indicating that the computer equipped with the motherboard or graphics card supports video output above 1080P.
Version of HDMI interface
HDMI 1.0
The earliest HDMI 1.0 version was launched in December 2002. Its biggest feature is the digital interface that integrates audio streams. Compared with the popular DVI interface in PC interfaces at that time, it is more advanced and more convenient. HDMI 1.0 version supports video streams from DVD to Blu-ray format, and has the function of CEC (consumer electronics control), that is, in the application, a common connection can be formed between all connected devices, and the device group has more convenient control.
HDMI 1.1
In May 2004, the HDMI 1.1 version interview. Added support for DVD audio.
HDMI 1.2
HDMI version 1.2 was launched in August 2005, which largely solved the problems of low resolution supported by HDMI 1.1 and poor compatibility with computer equipment. Version 1.2's pixels always run at 165MHz with a data volume of 4.95Gbps, so 1080P can be achieved. It can be said that version 1.2 solves the peer-to-peer problem between TV 1080P and computer.
HDMI 1.3
The HDMI 1.3 update in June 2006 brought the biggest change to increase the single-link bandwidth frequency to 340MHz, which allows these LCD TVs to obtain 10.2Gbps data transmission. The 1.3 version of the line is composed of 4 pairs of transmission channels. One pair of channels is a clock channel, and the other three pairs are TMDS channels (minimized transmission differential signal), and their transmission speed is 3.4GBPS respectively. Then 3 pairs are 3*3.4=10.2GPBS, which can greatly expand the 24-bit color depth supported by HDMI1.1 and 1.2 versions to 30-bit, 36-bit and 48-bit (RGB or YCbCr). HDMI 1.3 supports 1080P; some less demanding 3D also supports (theoretically not supported, some actually can).
HDMI 1.4
HDMI version 1.4 can already support 4K, but limited by the bandwidth of 10.2Gbps, it can only reach a resolution of 3840×2160 and a frame rate of 30FPS.
HDMI 2.0
The bandwidth of HDMI 2.0 is expanded to 18Gbps, supports plug and play and hot swap, supports 3840×2160 resolution and 50FPS, 60FPS frame rate. At the same time, it supports up to 32 channels in audio, and a maximum sampling rate of 1536kHz. HDMI 2.0 does not define new data lines, connectors, and interfaces, so it can maintain perfect backward compatibility with HDMI 1.x, and existing Type 2 data lines can be used directly. HDMI 2.0 will not replace HDMI 1.x, but is based on the enhancement of the latter. Any device that wants to support HDMI 2.0 must first ensure basic support for HDMI 1.x.
HDMI 2.0a
Not much has changed with HDMI 2.0a. Its major update is only one place where it adds support for HDR format transfer, which can greatly improve image quality.
HDMI 2.0b
HDMI2.0b is compatible with all previous versions of HDMI specifications, and is not much different from HDMI2.0a.
HDMI 2.1
HDMI2.1 is also the latest version of HDMI so far, and its improvement is the most significant, from 18Gbps to an astonishing 48Gbps, and only one cable can present 8K/60Hz pictures. At the same time, even the 10K resolution picture, HDMI 2.1 standard can also support.
Types of HDMI Interfaces
There are mainly five types of HDMI interfaces: A, B, C, D, and E.
1. HDMI A
HDMI A is the most widely used HDMI cable. The HDMI A interface has a total of 19 pins with a width of 13.9 mm and a thickness of 4.45 mm. Most audio and video devices used in daily life are equipped with this interface. For example: Blu-ray players, millet boxes, laptops, LCD TVs, projectors, etc.
2. HDMI B
HDMI B is relatively rare in life. It is mainly used in professional occasions. The HDMI B interface uses 29 pins and is 21mm wide. The data transmission capacity of HDMI B is almost twice that of HDMI A, which is equivalent to DVI dual link. Since the operating frequency of most audio and video equipment is below 165MHz, while the operating frequency of HDMI B is above 270MHZ, it often appears in professional application scenarios, such as the resolution of WQXGA 2560×1600.
3. HDMI C
HDMI C is often referred to as Mini HDMI, and it is primarily designed for small devices. HDMI C also uses 19pin, but the width is only 10.42mm and the thickness is 2.4mm. It is mainly used in portable devices, such as digital cameras, portable players and other devices.
4. HDMI D
HDMI D is commonly known as Micro HDMI. HDMI D size is further reduced. It is also 19pin, with a width of only 6.4 mm and a thickness of 2.8 mm, much like a Mini USB interface. Mainly used in small mobile devices. For example: mobile phones, tablets, etc.
5. HDMI E
HDMI E is mainly used for audio and video transmission in car entertainment systems. Due to the instability of the interior environment of the car, HDMI E Type is designed with the characteristics of impact resistance, moisture resistance, high strength, and a large temperature difference tolerance range. In terms of physical structure, the mechanical locking design ensures contact reliability.
Pin Definition of HDMI Interface
Take the HDMI Type A interface as an example to see the pin definitions. As shown in the figure below, HDMI Type A has 19 pins, of which pins 1 to 9 are data signals. Pins 10, 11 and 12 are the clock signals. 13 pins are CEC pins, 14 pins are empty, 15 pins are SCL pins, 16 pins are SDA pins, 17 pins are ground, 18 pins are positive 5V supply, 19 One pin is hot plug detection.
HDMI interface, as a brand-new digital multimedia transmission interface, has undergone more than ten years of development and has gone through the iterations of version 1.0 to version 2.1. It has the characteristics of high transmission bandwidth, strong anti-interference ability, and supports synchronous transmission of audio and video. The above advantages make it inevitable to gradually replace the traditional VGA and DVI interfaces.