HDMI (High-Definition Multimedia Interface) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audio device. HDMI is a digital replacement for analog video standards.
HDMI implements the EIA/CEA-861 standards, which define video formats and waveforms, transport of compressed and uncompressed LPCM audio, auxiliary data, and implementations of the VESA EDID. CEA-861 signals carried by HDMI are electrically compatible with the CEA-861 signals used by the Digital Visual Interface (DVI). No signal conversion is necessary, nor is there a loss of video quality when a DVI-to-HDMI adapter is used. The CEC (Consumer Electronics Control) capability allows HDMI devices to control each other when necessary and allows the user to operate multiple devices with one handheld remote control device.
Several versions of HDMI have been developed and deployed since the initial release of the technology, but all use the same cable and connector. Other than improved audio and video capacity, performance, resolution and color spaces, newer versions have optional advanced features such as 3D, Ethernet data connection, and CEC (Consumer Electronics Control) extensions.
Production of consumer HDMI products started in late 2003. In Europe, either DVI-HDCP or HDMI is included in the HD ready in-store labeling specification for TV sets for HDTV, formulated by EICTA with SES Astra in 2005. HDMI began to appear on consumer HDTVs in 2004 and camcorders and digital still cameras in 2006. As of January 6, 2015 (twelve years after the release of the first HDMI specification), over 4 billion HDMI devices have been sold.
The HDMI founders were Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, RCA, and Toshiba. Digital Content Protection, LLC provides HDCP (which was developed by Intel) for HDMI. HDMI has the support of motion picture producers Fox, Universal, Warner Bros. and Disney, along with system operators DirecTV, EchoStar (Dish Network) and CableLabs.
The HDMI founders began development on HDMI 1.0 on April 16, 2002, with the goal of creating an AV connector that was backward-compatible with DVI. At the time, DVI-HDCP (DVI with HDCP) and DVI-HDTV (DVI-HDCP using the CEA-861-B video standard) were being used on HDTVs. HDMI 1.0 was designed to improve on DVI-HDTV by using a smaller connector and adding audio capability and enhanced Y′CBCR capability and consumer electronics control functions.
The first Authorized Testing Center (ATC), which tests HDMI products, was opened by Silicon Image on June 23, 2003, in California, United States. The first ATC in Japan was opened by Panasonic on May 1, 2004, in Osaka. The first ATC in Europe was opened by Philips on May 25, 2005, in Caen, France. The first ATC in China was opened by Silicon Image on November 21, 2005, in Shenzhen. The first ATC in India was opened by Philips on June 12, 2008, in Bangalore. The HDMI website contains a list of all the ATCs.
According to In-Stat, the number of HDMI devices sold was 5 million in 2004, 17.4 million in 2005, 63 million in 2006, and 143 million in 2007. HDMI has become the de facto standard for HDTVs, and according to In-Stat, around 90% of digital televisions in 2007 included HDMI. In-Stat has estimated that 229 million HDMI devices were sold in 2008. On April 8, 2008 there were over 850 consumer electronics and PC companies that had adopted the HDMI specification (HDMI adopters). On January 7, 2009, HDMI Licensing, LLC announced that HDMI had reached an installed base of over 600 million HDMI devices. In-Stat has estimated that 394 million HDMI devices would sell in 2009 and that all digital televisions by the end of 2009 would have at least one HDMI input.
On January 28, 2008, In-Stat reported that shipments of HDMI were expected to exceed those of DVI in 2008, driven primarily by the consumer electronics market.
In 2008, PC Magazine awarded a Technical Excellence Award in the Home Theater category for an “innovation that has changed the world” to the CEC portion of the HDMI specification. Ten companies were given a Technology and Engineering Emmy Award for their development of HDMI by the National Academy of Television Arts and Sciences on January 7, 2009.
On October 25, 2011, the HDMI Forum was established by the HDMI founders to create an open organization so that interested companies can participate in the development of the HDMI specification. All members of the HDMI Forum have equal voting rights, may participate in the Technical Working Group, and if elected can be on the Board of Directors. There is no limit to the number of companies allowed in the HDMI Forum though companies must pay an annual fee of US$15,000 with an additional annual fee of $5,000 for those companies who serve on the Board of Directors. The Board of Directors is made up of 11 companies who are elected every 2 years by a general vote of HDMI Forum members. All future development of the HDMI specification take place in the HDMI Forum and are built upon the HDMI 1.4b specification. Also on the same day HDMI Licensing, LLC announced that there were over 1,100 HDMI adopters and that over 2 billion HDMI-enabled products had shipped since the launch of the HDMI standard. From October 25, 2011, all development of the HDMI specification became the responsibility of the newly created HDMI Forum.
On January 8, 2013, HDMI Licensing, LLC announced that there were over 1,300 HDMI adopters and that over 3 billion HDMI devices had shipped since the launch of the HDMI standard. The day also marked the 10th anniversary of the release of the first HDMI specification.
HDMI uses the Consumer Electronics Association/Electronic Industries Alliance 861 standards. HDMI 1.0 to HDMI 1.2a uses the EIA/CEA-861-B video standard, HDMI 1.3 uses the CEA-861-D video standard, and HDMI 1.4 uses the CEA-861-E video standard. The CEA-861-E document defines “video formats and waveforms; colorimetry and quantization; transport of compressed and uncompressed LPCM audio; carriage of auxiliary data; and implementations of the Video Electronics Standards Association (VESA) Enhanced Extended Display Identification Data Standard (E-EDID)”. On July 15, 2013, the CEA announced the publication of CEA-861-F, a standard that can be used by interfaces such as DVI, HDMI, and LVDS. CEA-861-F adds the ability to transmit several Ultra HD video formats and additional color spaces.
To ensure baseline compatibility between different HDMI sources and displays (as well as backward compatibility with the electrically compatible DVI standard) all HDMI devices must implement the sRGB color space at 8 bits per component. Ability to use the Y′CBCR color space and higher color depths (“deep color”) is optional. HDMI permits sRGB 4:4:4 chroma subsampling (8–16 bits per component), xvYCC 4:4:4 chroma subsampling (8–16 bits per component), Y′CBCR 4:4:4 chroma subsampling (8–16 bits per component), or Y′CBCR 4:2:2 chroma subsampling (8–12 bits per component). The color spaces that can be used by HDMI are ITU-R BT.601, ITU-R BT.709-5 and IEC 61966-2-4.
For digital audio, if an HDMI device has audio, it is required to implement the baseline format: stereo (uncompressed) PCM. Other formats are optional, with HDMI allowing up to 8 channels of uncompressed audio at sample sizes of 16-bit, 20-bit and 24-bit, with sample rates of 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz and 192 kHz. HDMI also carries any IEC 61937-compliant compressed audio stream, such as Dolby Digital and DTS, and up to 8 channels of one-bit DSD audio (used on Super Audio CDs) at rates up to four times that of Super Audio CD. With version 1.3, HDMI allows lossless compressed audio streams Dolby TrueHD and DTS-HD Master Audio. As with the Y′CBCR video, audio capability is optional. Audio return channel (ARC) is a feature introduced in the HDMI 1.4 standard. “Return” refers to the case where the audio comes from the TV and can be sent “upstream” to the AV receiver using the HDMI cable connected to the AV receiver. An example given on the HDMI website is that a TV that directly receives a terrestrial/satellite broadcast, or has a video source built in, sends the audio “upstream” to the AV receiver.
The HDMI standard was not designed to pass closed caption data (for example, subtitles) to the television for decoding. As such, any closed caption stream must be decoded and included as an image in the video stream(s) prior to transmission over an HDMI cable to appear on the DTV. This limits the caption style (even for digital captions) to only that decoded at the source prior to HDMI transmission. This also prevents closed captions when transmission over HDMI is required for upconversion. For example, a DVD player that sends an upscaled 720p/1080i format via HDMI to an HDTV has no way to pass Closed Captioning data so that the HDTV can decode it, as there is no line 21 VBI in that format.
The plug (male) connector outside dimensions are 13.9 mm × 4.45 mm, and the receptacle (female) connector inside dimensions are 14 mm × 4.55 mm. There are 19 pins, with bandwidth to carry all SDTV, EDTV, HDTV, UHD, and 4K modes. It is electrically compatible with single-link DVI-D.
This connector is 21.2 mm × 4.45 mm and has 29 pins, carrying six differential pairs instead of three, for use with very high-resolution displays such as WQUXGA (3840×2400). It is electrically compatible with dual-link DVI-D, but has not yet been used in any products. With the introduction of HDMI 1.3, the maximum bandwidth of single-link HDMI exceeded that of dual-link DVI-D. As of HDMI 1.4, the pixel clock rate crossover frequency from single to dual-link has not been defined.
This Mini connector is smaller than the type A plug, measuring 10.42 mm × 2.42 mm but has the same 19-pin configuration. It is intended for portable devices. The differences are that all positive signals of the differential pairs are swapped with their corresponding shield, the DDC/CEC Ground is assigned to pin 13 instead of pin 17, the CEC is assigned to pin 14 instead of pin 13, and the reserved pin is 17 instead of pin 14. The type C Mini connector can be connected to a type A connector using a type A-to-type C cable.
This Micro connector shrinks the connector size to something resembling a micro-USB connector, measuring only 5.83 mm × 2.20 mm. For comparison, a micro-USB connector is 6.85 mm × 1.8 mm and a USB Type-A connector is 11.5 mm × 4.5 mm. It keeps the standard 19 pins of types A and C, but the pin assignment is different from both.
The Automotive Connection System has a locking tab to keep the cable from vibrating loose and a shell to help prevent moisture and dirt from interfering with the signals. A relay connector is available for connecting standard consumer cables to the automotive type.
The HDMI alternate mode lets a user connect the reversible USB-C connector with the HDMI source devices (mobile, tablet, laptop). This cable connects to video display/sink devices using any of the native HDMI connectors. This is an HDMI cable, in this case a USB-C to HDMI cable.
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