Overview of HDMI Interfaces and Its Advantages.
Overview of HDMI Interfaces and Its Advantages. - Table of contents:
HDMI interface, or High Definition Multimedia Interface, is a type of digital interface that is often compared to an advanced form of the standard A/V cable. It allows for the transmission of audio and video signals in digital format without any need for D/A or A/D conversion before transmission can occur. This makes HDMI one of the best ways to stream data between digital devices.
To put it simply, the HDMI interface is an interface used to transmit video and audio signals. Content production equipment can transmit video and audio to viewing equipment with high efficiency through HDMI. This type of interface is more common in devices such as smart TVs, set-top boxes, and projectors, and its interface is in an inverted trapezoidal shape, which is relatively flat.
1. The evolution history of HDMI:
In fact, the technology that first appeared in the field of transmission was DVI instead of HDMI. The appearance of the DVI interface was also widely used in the field of output at that time. However, with the development of digital high-definition audio-visual technology, the DVI interface has gradually exposed various problems. Even to a certain extent, it has become the bottleneck of the progress of digital imaging technology.
Therefore, whether it is IT manufacturers, flat-panel TV manufacturers, or many Hollywood publishers, there is an urgent need for a better interface technology that can meet the future development of the high-definition video industry. It is for these reasons that the HDMI standard birth.
The earliest version of HDMI 1.0 was launched in December 2002. Its biggest feature is the digital interface that integrates audio streams. Compared with the popular DVI interface in the PC interface at that time, it is more advanced and more convenient. HDMI1.0 version supports video streams from DVD to Blu-ray format, and has CEC (consumer electronics control) function, that is, in the application, a common connection can be formed between all connected devices, and the device group has more convenient control.
In May 2004, HDMI 1.1 version interview. Added support for DVD-Audio.
The HDMI1.2 version was launched in August 2005, which largely solved the problems of low resolution supported by HDMI1.1 and poor compatibility with computer equipment. Version 1.2 has a pixel clock operating frequency of 165MHz and a data volume of 4.95Gbps, so 1080P can be achieved. It can be considered that version 1.2 solves the point-to-point problem of 1080P TV and computer.
In June 2006, HDMI1.3 was updated, and the biggest change was to increase the single-link bandwidth frequency to 340MHz, which also allowed these LCD TVs to obtain 10.2Gbps data transmission capacity. The 1.3 version of the line is composed of 4 pairs of transmission channels, where one pair of channels is a clock channel, and the other three pairs are TMDS channels (minimize transmission of differential signals), and their transmission speeds are 3.4GBPS respectively. Then 3 pairs are 3*3.4=10.2GPBS, and it 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). HDMI1.3 supports 1080P; some less demanding 3D also supports (theoretically not supported, but actually some can).
HDMI version 1.4 can already support 4K, but limited by the bandwidth of 10.2Gbps, it can only reach a maximum resolution of 3840×2160 and a frame rate of 30FPS.
The bandwidth of HDMI2.0 has been expanded to 18Gbps, supports plug and play and hot plug, and supports 3840×2160 resolution and 50FPS, 60FPS frame rate. At the same time, it supports up to 32 audio channels and a maximum sampling rate of 1536kHz. HDMI 2.0 does not define new data cables, connectors, and interfaces, so it can maintain perfect backward compatibility with HDMI 1.x, and existing Type 2 data cables can be used directly. HDMI 2.0 will not replace HDMI1.x but is based on the enhancement of the latter. If any device wants to support HDMI 2.0, it must first ensure the basic support for HDMI 1.x.
HDMI 2.0a has not changed much. Its main update is only one place, which is to add support for HDR format transmission, which can significantly enhance image quality.
HDMI2.0b is compatible with all previous versions of HDMI and is not much different from HDMI2.0a. HDMI2.0b is also the latest version of HDMI so far.
2. HDMI interface type
HDMI interface is divided into A, B, C, and D 4 types.
- Among them, type A (Type A) is the most common. Generally, flat-screen TVs or video equipment provide interfaces of this size. Type A has 19 pins, a width of 13.9 mm, and a thickness of 4.45 mm. The devices that can be seen now are 99 % HDMI ports of this size.
- Type B (Type B) is very rare. It has 29 pins and a width of 21 mm. The transmission bandwidth is almost double that of Type A. It is a completely too “tough” in-home application, and now it is only used on some professional occasions.
- Type C (Type 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 its application range is very small.
- Type D (Type D) is the latest interface type, the size is further reduced, it adopts a double-row pin design, the size is similar to the mini USB interface, and it is more suitable for portable and vehicle-mounted devices.
Although the HDMI interfaces are different, their functions are the same. Generally, a qualified HDMI interface has a plugging life of no less than 5,000 times. It can be used for 10 years after plugging and unplugging every day.
It should be said to be very durable. It is also worth mentioning that HDMI can be backward compatible with a DVI interface. Some older DVI devices can be connected through commercially available HDMI-DVI adapters because DVI also uses TMDS. After the device is connected, it will find that the DVI device There is no CEC (consumer electronics control) function, and it cannot accept audio signals, but it basically does not affect the transmission of video signals (may require grayscale adjustment), so some kiosk lcd monitor with only DVI interfaces can also be connected to HDMI devices.
3. Corresponding function of HDMI interface
1. HDCP 2.2, this technology can protect high-value digital movies, TV programs, and audio content from illegal theft and copying.
2. HDMI-ARC (Audio Return Channel, sound return) function, used for the output of TV digital audio, can be connected to the power amplifier that also supports the ARC function, and the sound of the TV can be transmitted to the power amplifier.
3. Bit refers to the color depth. The general notebook screen is 6bit, the high-end 8bit, and the special professional 10bit, which can be understood as the color depth of 2 to the 10th power, and 10bit specifically refers to a video coding technology that can provide very high Excellent video quality, can show extraordinary delicacy in color gradation and change, but the configuration requirements for playing 10bit are still very high.
4. MHL technology uses only five cables to transmit up to 4K ultra-high definition uncompressed video with eight-channel digital audio, while also charging mobile devices.
4. The advantages of HDMI summary
1. Quality: HDMI is a digital interface because all analog connections (such as component video or S-video) require no loss when converting from analog to digital, so it can provide 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. Small, high-contrast details such as text bring out the difference to the extreme.
2. Ease of use: HDMI integrates video and multi-channel audio in a single cable, thereby eliminating the cost, complexity, and confusion of multiple cables used in current A/V systems. This is especially useful when upgrading or adding equipment.
3. High Intelligence: HDMI supports two-way communication between video sources (such as DVD players) and DTV, and realizes new functions, such as automatic configuration and one-key playback. By using HDMI, the device automatically transmits the most efficient format for the connected display (e.g. 480p vs 720p, 16:9 vs 4:3) eliminating the need for consumers to scroll through all the format options to guess the best viewing format.