The English full name of HDMI is "High Definition Multimedia Interface", and Chinese means high definition multimedia interface. The HDMI interface can provide data transmission bandwidth up to 5Gbps, which can transmit uncompressed digital audio signals and high-resolution video signals.

 

    Because there is no need to perform digital-to-analog or analog-to-digital conversion before signal transmission, the highest quality video and audio signal transmission can be guaranteed. The advantage of using HDMI is that only one HDMI cable is needed to transmit audio and video signals. For consumers, HDMI technology not only provides clear picture quality, but also uses the same cable for audio / video, which greatly simplifies the home theater system installation.

 

 

 

    In April 2002, seven companies including Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, Toshiba, etc. established the HDMI organization and began to develop a new standard for digital video / audio transmission. At the end of the year, the High-definition Digital Multimedia Interface (HDMI 1.0) standard was promulgated.

 

 

 

    HDMI is compatible with DVI (Digital Visual Interface) on the pins, but it uses different packages, which can be regarded as the enhancement and extension of DVI. Both are compatible. Compared with DVI, HDMI can transmit digital audio signals and adds support for HDCP (High-bandwith digital content protection). HDMI supports a data transmission rate of 5Gbps, and can transmit up to 15 meters, which is sufficient for a 1080p video and an 8-channel audio signal. And a 1080p video and an 8-channel audio signal require less than 4GB / s, so HDMI has a lot of margin.

 

    In addition, HDMI supports EDID (Extended Display Identification Data), DDC (Data Display Channel, for reading EDID), so HDMI devices have the characteristics of "plug and play", the signal source and The display devices will automatically “negotiate” to automatically select the most suitable video / audio format.

 

    The HDMI organization also announced a high-resolution multimedia interface-HDMI version 1.2-better compatible with PC systems. This revision adds several very important improvements to facilitate PC connection and transmission of digital audio streams (SACD, etc.). This digital audio and video interface has maintained its advanced nature, which is obviously a response to VESA's launch of the Display port interface. So far, more than 250 manufacturers and 470 different types of products have adopted the HDMI interface.

 

    The DVD Copy Control Association (CCA) stipulates that all DVD players that play CSS-protected content and have image quality higher than 480p / 576p must have HDMI-HDCP or DVI-HDCP output terminals. The US FCC (Federal Communications Commission) also requires that all "digital cable-ready" TVs sold after July 1, 2005 must have HDMI-HDCP or DVI-HDCP input terminals.

 

    In addition, CableLabs also stipulates in its OpenCable plan that all high-definition digital TV boxes (HD-STBs) must have HDMI-HDCP or DVI-HDCP output terminals. EICTA, which represents the European information and communication technology and consumer electronics industry, also announced in January 2005 that any display device with “HD Ready” must receive high-resolution content transmission through the HDMI or DVI digital interface, and its HDMI Or the DVI input terminal must support HDCP.

 

    All these regulations have further strengthened HDMI's position in the market. HDMI has become the de facto interface standard for digital TVs and consumer electronics.

 

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