Even if it is not a video audiophile, many people can't get rid of the influence of the HDMI cable. The new flat-panel TV at home is likely to have been 4K resolution, because the price of 4K TV has been falling all the time, and the distance from 2K high-definition TV is getting more and more. Small, consumers will of course choose new technology products. If you can buy a set-top box for Internet TV, or a high-definition playback box that can play downloaded programs, or even a portable high-quality MP4 player, you will be indispensable. HDMI cable connection. From the computer street one hundred yuan, to the audio store one million yuan, what is the difference between these HDMI lines?
Evolution of image transmission interface
The earliest analog video terminal is called Composite Video, and the yellow RCA connector represents the image. This is the oldest input and output interface except for RF. Later, S-Video (color and brightness separation) and Component (components of color difference) were developed. , the brightness, chroma, sync pulse in the image is decomposed to each other), D-Terminal, VGA, DVI and other interfaces. In any case, these terminals are separate from the image and sound.
In the 1970s, a 21-pin SCART interface was born in Europe. The image and sound were all integrated. The image and left and right channels were Bi-directional duplex, and also contained RGB and S-Video signals. Widescreen, a pioneer in the automation of home consumer electronics. SCART has been able to support high-definition video and audio signals so far, and its functions are fully realized on satellite receivers. European-standard DVB satellite receivers must be localized. Using the SCART connector, in order to cope with Pay TV pay TV programs, SCART's data convergence eliminates the connection of the pay-TV decoder, and also controls the position of the dish antenna, which can operate the polarity of the collector. Receiving programs from different satellites. SCART's control technology development experience has created the technical concept of control channels. Later, the design of IEEE 1394 and HDMI CEC control channels was inspired.
The yellow RCA connector is a common Composite Video terminal; the black is the S-Video terminal that can separate the chroma and brightness; the red, blue and green are the Component component.
IEEE 1394 is called FireWire by Apple. Since Sony did not use FireWire as a brand before Apple registered it as a trademark, Sony's DV originally used this interface, so it is also called DV terminal.
The transmission efficiency of IEEE 1394 is quite excellent, and the command of the control channel is also very complete. As long as it is a player of Japanese high-definition satellite, it must be familiar with the control method of i.Link. In the use of computer network, IEEE 1394 also has a function. Called IP over IEEE 1394, this interconnection configuration, even without a Hub, can form a regional network for external network connection through the IEEE 1394 bus. However, in 2007 Microsoft announced that IEEE 1394 The IP network on the bus no longer provides support for all updated versions of Windows, which means that IEEE 1394 faces the fate of the last generation.
At the same time, the Blu-ray machine is attacking the city, and the speed of i.Link no longer meets the precise and high-speed work efficiency. Therefore, Japanese digital broadcasting gradually gives up this interface. On the computer side, IEEE 1394 must be paid for authorization, and now it is also equipped with USB with high-speed technology. 3.0 replaced. In 2005, Matsushita of Japan launched the amazing VIERA Link technology, learning the SCART single-wire data bus to transmit AV.Link signals, using a single remote control to operate the surrounding machines, and promoting the HDMI 1.2a revision. The CEC function was announced, and Panasonic later changed to HDMI as the technology for system linkage control.
The SCART connector introduced in Europe in the 1970s can support high-resolution audio and video signals. The development of its control technology has inspired the design of IEEE 1394 and HDMI.
In 1999, the DVI terminal was launched based on the patented technology of Silicon Image of the United States. At that time, it was designed to unify the digital display interface standard of the new era.
Apple is called IEEE 1394, and SONY calls it i.LINK, and it has gradually faded out of the market.
The birth of HDMI
In April 2002, seven companies including Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, and Toshiba jointly established the HDMI high-definition multimedia interface organization, and began to develop a new digital video that meets the standards of the high-definition era. Audio interface technology, officially released the HDMI 1.0 standard on December 9 of the same year, officially kicked off HDMI (High-Definition Multimedia Interface).
In fact, as early as 1999, in order to meet the requirements of high-quality graphics in the digital age, the DDWG data display working group based on the patented technology of Silicon Image of the United States, launched a interface called DVI, designed to unify the digital display of the new era. Interface standard. This technology has been supported by IT companies Intel, DELL, HP, IBM and other large enterprises. But with the development of digital HD video, DVI interface has gradually exposed various problems, and even become a bottleneck of progress. DVI interface exists The main problem is:
The DVI interface considers the object of PC, which is generally compatible with flat-panel TVs.
The DVI interface lacks support for image copyright protection.
The DVI interface only supports 8-bit RGB signal transmission, which does not allow the wide color gamut display terminal to perform optimally.
For compatibility reasons, the DVI interface has reserved a lot of pins to support analog devices, resulting in a larger interface size.
The DVI interface can only transmit image signals, and does not consider support for digital audio signals.
The HDMI interface was officially released in December 2002.
Due to the above defects, the DVI interface has not been able to better meet the development needs of the entire industry. Therefore, whether it is IT manufacturers, flat-panel TV manufacturers, or many publishers in Hollywood, there is an urgent need for a better future. The interface technology of the development of image quality video industry, HDMI standard was born in 焉. Because HDMI can transmit image and audio signals at the same time, it greatly reduces the number of cables and facilitates the practical construction of home theater and consumer electronics products. With decades of development and evolution, the HDMI interface has been widely used in many fields such as flat-panel TVs, digital cameras/cameras, high-definition multimedia players, projectors, PCs, mobile phones, tablets, and automotive electronics. , become an indispensable audio and video interface in consumer electronics.
Type of HDMI interface
There are five interfaces for HDMI, and only four of them are actually used, namely:
HDMI A Type
There are a total of 19 pins, which is the most common HDMI connector specification for audio-visual equipment. It is equivalent to DVI Single-Link transmission. The internal pins of the A type are arranged in a ring shape, and the error of the standard size is controlled within a relatively small range ( 0.05mm) to ensure good contact.
HDMI B Type
A total of 29 pins, can transfer A type twice the amount of TMDS data, equivalent to DVI Dual-Link transmission, used to transmit high-resolution graphics (WQXGA 2560 × 1600 or more). But because the transmission frequency must be increased to 270 when transmitting TMDS Above MHz, most devices can only work stably below 165 MHz before the HDMI 1.3 IC, so this interface is not used in any product.
HDMI C Type
Called Mini HDMI, a total of 19 pins, can be said to be a reduced version of the HDMI A type, but the definition of the foot has changed, mainly used in portable devices, such as DV, digital cameras, portable multimedia players.
HDMI D Type
Also known as Micro HDMI, a total of 19 pins, the pin definition has changed, the interface is about 50% smaller than the Mini HDMI, which can provide up to 1080p resolution and up to 5GB transmission speed for portable devices such as cameras and mobile phones. .
HDMI E Type
A total of 19 pins, mostly used in the automotive industry, the first version of the 1.4 version appeared in the market. E-type joint design is particularly strict environmental requirements, when the joints are connected to each other, attention should be paid to earthquake resistance, moisture, temperature difference, noise interference, etc., because of the environment on the car It is not as stable as home, so this is the only structure with interlocking interlock in HDMI type connectors.
HDMI version
HDMI's earliest interface specification HDMI 1.0 was released in December 2002, version 1.1 was released in 2004, version 1.2 was released in 2005, version 1.3 was released in 2006, version 1.4 was released in 2009, and the latest version 2.0 was released in 2013. Every version update is to expand the scope of application, increase functionality, and increase the speed of implementation.
Version 1.0 → R&D, trial phase
Version 1.1 → Image only (1080p)
1.2 → Image (1080p) + Stereo
1.3 → Image (1080p) + Support for 7.1 channels
1.4 → Basically the same as version 1.3, add Ethernet channel, audio return channel, 3D over HDMI, support 4K resolution, expand support for color gradation, and Micro HDMI connector
The sponsors of the HDMI standards, when promoting the HDMI standard, are not based on the principle of salvation, simply promoting a leading technology, there is a deeper commercial reason behind it. This is from the HDMI chip. The main supplier, Silicon Image, said that the HDMI standard was jointly developed by seven companies including Hitachi, Panasonic, Philips, Silicon Image, SONY, Thomson and Toshiba, and the seven companies have mastered the core technology of the HDMI standard. It is Silicon Image of the United States. It not only masters the HDMI core's TMDS (transition minimized differential signaling) technology, but also is the world's largest supplier of HDMI master chips. Therefore, the popularity of the HDMI standard is There is a direct interest relationship between Silicon Image.
Different sizes of HDMI connectors are available for different devices.
HDMI is for a fee!
In order to better promote the HDMI standard, and led by Silicon Image, a special wholly-owned subsidiary HDMI Licensing, LLC. has been established. This company is responsible for the update of the HDMI standard, the promotion to equipment vendors, and the HDMI for various devices. Product certification and testing work. The other six companies that originally developed the HDMI standard became the founders of HDMI Licensing, but the share was relatively small.
There is no free lunch in the world, HDMI Licensing company pays the corresponding fee. The cost is also composed more, mainly the following kinds of charges.
1. Each device using HDMI is required to pay an annual premium of 10,000 US dollars. If you want to join HDCP (High-bandwidth Digital Content Protection) function, you need to pay an additional 10,000 US dollars. For HDCP function, Few manufacturers will choose to give up, otherwise their products will lack basic competitiveness.
Second, in order to ensure the compatibility between devices equipped with HDMI interface, manufacturers also need to participate in the HDMI ATC compatibility test conducted by Authorized Testing Center, including imaging equipment, receivers, forwarding devices, wires, etc. Charge separately.
Third, each piece of equipment used for commercialization, you also need to pay 15 cents of royalties and 4 cents of HDCP royalties. If you use the HDMI logo, you need to pay another 5 cents for each piece of equipment.
The above three charges are only part of the revenue of HDMI Licensing, and the other part of the revenue comes from the sale of HDMI master chips. At present, manufacturers of HDMI master chips in the world, in addition to Silicon Image, and Agilent and other manufacturers. Digital display In technology, there are currently three mainstream technologies in the world, TMDS is developed by Silicon Image, LVDS is patented by National Semiconductor, and GVIF technology developed by Sony of Japan has its own strengths. It is puzzling that Sony has good technology. Why is it possible to jointly promote the HDMI TMDS technology with Silicon Image? The strategy of commercial competition is ingenious.
Introduction
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