Tmds Hdmi Signals Assignment

TypeDigital audio/video/data connector
Production history

HDMI Founders (7 companies)[1]

HDMI Forum (83 companies)[2]

  • Allion Labs, Inc.
  • Alphaholdings Inc.
  • Advanced Micro Devices, Inc.
  • Analog Devices, Inc.
  • Analogix Semiconductor
  • ARRIS Group Inc.
  • Astrodesign
  • Bitec
  • Bose Corporation
  • Broadcom Corporation
  • Cadence Design Systems, Inc.
  • Chrontel
  • Corning Inc.
  • Crestron Electronics
  • Diodes Incorporated
  • DisplayLink Corp.
  • Dolby Laboratories, Inc.
  • DTS, Inc.
  • Elka
  • Explore Microelectronics Inc.
  • Extron Electronics
  • Foxconn Technology Group
  • Fraunhofer Society
  • Global Unichip Corp.
  • Google Inc.
  • Granite River Labs Inc.
  • Hardent
  • Himax Technologies, Inc.
  • HiSilicon Co., Ltd.
  • Hitachi, Ltd.
  • Hosiden
  • Intel Corporation
  • Integrated Service Technology Inc.
  • ITE Tech, Inc.
  • Japan Aviation Electronics Industry, Ltd.
  • JCE
  • JVC Kenwood Corp.
  • Korea Electric Terminal Co., Ltd.
  • Keysight Technologies
  • Lattice Semiconductor
  • LG Electronics
  • Marvell Technology Group, Ltd.
  • MediaTek Inc.
  • MegaChips Technology America Corp.
  • Mentor Graphics, Inc.
  • Microsoft Corporation
  • MStar Semiconductor, Inc.
  • Murata Manufacturing Co., Ltd.
  • Netflix
  • Novatek
  • Nvidia Corporation
  • NXP Semiconductors
  • Onkyo Corporation
  • Panasonic Corporation
  • Parade Technologies
  • Philips N.V.
  • Pioneer Corporation
  • Qualcomm, Inc.
  • Realtek Semiconductor Corp.
  • Rohde & Schwarz GmbH & Co. KG
  • Samsung Electronics Co., Ltd.
  • Semtech Corporation
  • Sharp Corporation
  • Sigma Designs
  • Silicon Line
  • Sky plc
  • Sony Corporation
  • Spectra7 Microsystems Inc.
  • STMicroelectronics N.V.
  • Synopsys, Inc.
  • Technicolor SA
  • Tektronix, Inc.
  • Teledyne LeCroy
  • TeVeAe, Inc.
  • Texas Instruments Inc.
  • Toshiba Corporation
  • TP Vision
  • Underwriters Laboratories LLC
  • Valens Semiconductor
  • ViXS Systems Inc.
  • Wilder Technologies, LLC
  • Xilinx, Inc.
DesignedDecember 2002
ManufacturerHDMI Adopters (over 1,700 companies)
SupersededDVI, VGA
General specifications
Width13.9 mm (type A), 10.42 mm (type C), 6.4 mm (type D)
Height4.45 mm (type A), 2.42 mm (type C), 2.8 mm (type D)
Hot pluggableYes
Audio signalLPCM, Dolby Digital, DTS, DVD-Audio, Dolby Digital Plus, Dolby TrueHD, DTS-HD High Resolution Audio, DTS-HD Master Audio, MPCM, DSD, DST, Dolby Atmos, DTS:X
Video signalMaximum resolution limited by available bandwidth
PinsTypes A, C, & D (19), Type B (29)
Data signalYes
BitrateUp to 48 Gbit/s in HDMI 2.1
Pin out
HDMI type A receptacle (female)
Pin 1TMDS Data2+
Pin 2TMDS Data2 Shield
Pin 3TMDS Data2−
Pin 4TMDS Data1+
Pin 5TMDS Data1 Shield
Pin 6TMDS Data1−
Pin 7TMDS Data0+
Pin 8TMDS Data0 Shield
Pin 9TMDS Data0−
Pin 10TMDS Clock+
Pin 11TMDS Clock Shield
Pin 12TMDS Clock−
Pin 13CEC
Pin 14
Pin 15SCL (I²C serial clock for DDC)
Pin 16SDA (I²C serial data for DDC)
Pin 17Ground (for DDC, CEC, ARC, and HEC)
Pin 18+5 V (min. 0.055 A)[3]
Pin 19
  • Hot Plug Detect (all versions)
  • HEAC− (HDMI 1.4+, optional, HDMI Ethernet Channel and Audio Return Channel)

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.[4] 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, uncompressed, and LPCM audio, auxiliary data, and implementations of the VESA EDID.[5][6](p. III) 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.[6](§C) 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.[6](§6.3)

Several versions of HDMI have been developed and deployed since 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.[7] 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 consumerHDTVs in 2004 and camcorders and digital still cameras in 2006.[8][9] As of January 6, 2015 (twelve years after the release of the first HDMI specification), over 4 billion HDMI devices have been sold.[10]


The HDMI founders were Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, RCA and Toshiba.[1] Digital Content Protection, LLC provides HDCP (which was developed by Intel) for HDMI.[11] HDMI has the support of motion picture producers Fox, Universal, Warner Bros. and Disney, along with system operators DirecTV, EchoStar (Dish Network) and CableLabs.[4]

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.[12][13] 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.[13][14][15] HDMI 1.0 was designed to improve on DVI-HDTV by using a smaller connector and adding audio capability and enhanced YCbCr capability and consumer electronics control functions.[13][14]

The first Authorized Testing Center (ATC), which tests HDMI products, was opened by Silicon Image on June 23, 2003, in California, United States.[16] The first ATC in Japan was opened by Panasonic on May 1, 2004, in Osaka.[17] The first ATC in Europe was opened by Philips on May 25, 2005, in Caen, France.[18] The first ATC in China was opened by Silicon Image on November 21, 2005, in Shenzhen.[19] The first ATC in India was opened by Philips on June 12, 2008, in Bangalore.[20] The HDMI website contains a list of all the ATCs.[21]

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.[22][23][24] HDMI has become the de facto standard for HDTVs, and according to In-Stat, around 90% of digital televisions in 2007 included HDMI.[22][25][26][27][28] In-Stat has estimated that 229 million HDMI devices were sold in 2008.[29] On April 8, 2008 there were over 850 consumer electronics and PC companies that had adopted the HDMI specification (HDMI adopters).[30][31] On January 7, 2009, HDMI Licensing, LLC announced that HDMI had reached an installed base of over 600 million HDMI devices.[31] 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.[31]

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.[22][32]

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.[33] 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.[34]

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.[35][36] 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.[36] 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.[36] The Board of Directors is made up of 11 companies who are elected every 2 years by a general vote of HDMI Forum members.[36] All future development of the HDMI specification take place in the HDMI Forum and are built upon the HDMI 1.4b specification.[36] 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.[1][35] From October 25, 2011, all development of the HDMI specification became the responsibility of the newly created HDMI Forum.[35]

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.[10][37] The day also marked the 10-year anniversary of the release of the first HDMI specification.[10][37]


The HDMI specification defines the protocols, signals, electrical interfaces and mechanical requirements of the standard.[6](p. V) The maximum pixel clock rate for HDMI 1.0 is 165 MHz, which is sufficient to allow 1080p and WUXGA (1920×1200) at 60 Hz. HDMI 1.3 increases that to 340 MHz, which allows for higher resolution (such as WQXGA, 2560×1600) across a single digital link.[38] An HDMI connection can either be single-link (type A/C/D) or dual-link (type B) and can have a video pixel rate of 25 MHz to 340 MHz (for a single-link connection) or 25 MHz to 680 MHz (for a dual-link connection). Video formats with rates below 25 MHz (e.g., 13.5 MHz for 480i/NTSC) are transmitted using a pixel-repetition scheme.[4]


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.[6](p. III) The CEA-861-E document defines "video formats and waveforms; colorimetry and quantization; transport of compressed and uncompressed, as well as Linear Pulse Code Modulation (LPCM), audio; carriage of auxiliary data; and implementations of the Video Electronics Standards Association (VESA) Enhanced Extended Display Identification Data Standard (E-EDID)".[39] 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.[40] CEA-861-F adds the ability to transmit several Ultra HD video formats and additional color spaces.[40]

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.[6](§6.2.3) Ability to use the YCbCr 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), YCbCr 4:4:4 chroma subsampling (8–16 bits per component), or YCbCr 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.[6](§§6.5,6.7.2)

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.[6](§7) 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.[6](§7) With version 1.3, HDMI allows lossless compressed audio streams Dolby TrueHD and DTS-HD Master Audio.[6](§7) As with the YCbCr video, audio capability is optional. Audio return channel (ARC) is a feature introduced in the HDMI 1.4 standard.[41] "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.[41] 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.[41]

The HDMI standard was not designed to pass closed caption data (for example, subtitles) to the television for decoding.[42] 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.

Communication channels[edit]

HDMI has three physically separate communication channels, which are the DDC, TMDS and the optional CEC.[6](§8.1) HDMI 1.4 added ARC and HEC.[41][43]

Display Data Channel (DDC)[edit]

Main article: Display Data Channel

The Display Data Channel (DDC) is a communication channel based on the I²C bus specification. HDMI specifically requires the device implement the Enhanced Display Data Channel (E-DDC), which is used by the HDMI source device to read the E-EDID data from the HDMI sink device to learn what audio/video formats it can take.[6](§§8.1,CEC-1.2–CEC-1.3) HDMI requires that the E-DDC implement I²C standard mode speed (100 kbit/s) and allows it to optionally implement fast mode speed (400 kbit/s).[6](§4.2.8)

The DDC channel is actively used for High-bandwidth Digital Content Protection (HDCP).

Transition-Minimized Differential Signaling (TMDS)[edit]

Transition-minimized differential signaling (TMDS) on HDMI interleaves video, audio and auxiliary data using three different packet types, called the Video Data Period, the Data Island Period and the Control Period. During the Video Data Period, the pixels of an active video line are transmitted. During the Data Island period (which occurs during the horizontal and vertical blanking intervals), audio and auxiliary data are transmitted within a series of packets. The Control Period occurs between Video and Data Island periods.[6](§5.1.2)

Both HDMI and DVI use TMDS to send 10-bit characters that are encoded using 8b/10b encoding that differs from the original IBM form for the Video Data Period and 2b/10b encoding for the Control Period. HDMI adds the ability to send audio and auxiliary data using 4b/10b encoding for the Data Island Period. Each Data Island Period is 32 pixels in size and contains a 32-bit Packet Header, which includes 8 bits of BCH ECC parity data for error correction and describes the contents of the packet. Each packet contains four subpackets, and each subpacket is 64 bits in size, including 8 bits of BCH ECC parity data, allowing for each packet to carry up to 224 bits of audio data. Each Data Island Period can contain up to 18 packets. Seven of the 15 packet types described in the HDMI 1.3a specifications deal with audio data, while the other 8 types deal with auxiliary data. Among these are the General Control Packet and the Gamut Metadata Packet. The General Control Packet carries information on AVMUTE (which mutes the audio during changes that may cause audio noise) and Color Depth (which sends the bit depth of the current video stream and is required for deep color). The Gamut Metadata Packet carries information on the color space being used for the current video stream and is required for xvYCC.[6](§§5.2–5.3,6.5.3,6.7.2,6.7.3)

Consumer Electronics Control (CEC)[edit]

Main article: Consumer Electronics Control

Consumer Electronics Control (CEC) is an HDMI feature designed to allow the user to command and control up to 15 CEC-enabled devices, that are connected through HDMI,[44][45] by using only one of their remote controls (for example by controlling a television set, set-top box, and DVD player using only the remote control of the TV). CEC also allows for individual CEC-enabled devices to command and control each other without user intervention.[6](§CEC-3.1)

It is a one-wire bidirectional serial bus that is based on the CENELEC standard protocol to perform remote control functions.[46] CEC wiring is mandatory, although implementation of CEC in a product is optional.[6](§8.1) It was defined in HDMI Specification 1.0 and updated in HDMI 1.2, HDMI 1.2a and HDMI 1.3a (which added timer and audio commands to the bus).[6](§§CEC-1.2,CEC-1.3,CEC-3.1,CEC-5) USB to CEC adapters exist that allow a computer to control CEC-enabled devices.[47][48][49][50]

HDMI Ethernet and Audio Return Channel[edit]

Introduced in HDMI 1.4, HDMI Ethernet and Audio Return Channel (HEAC) adds a high-speed bidirectional data communication link (HEC) and the ability to send audio data upstream to the source device (ARC). HEAC utilizes two lines from the connector: the previously unused Reserved pin (called HEAC+) and the Hot Plug Detect pin (called HEAC−).[51](§HEAC-2.1) If only ARC transmission is required, a single mode signal using the HEAC+ line can be used, otherwise, HEC is transmitted as a differential signal over the pair of lines, and ARC as a common mode component of the pair.[51](§HEAC-2.2)

Audio Return Channel (ARC)

ARC is an audio link meant to replace other cables between the TV and the A/V receiver or speaker system.[41] This direction is used when the TV is the one that generates or receives the video stream instead of the other equipment.[41] A typical case is the running of an app on a smart TV such as Netflix, but reproduction of audio is handled by the other equipment.[41] Without ARC, the audio output from the TV must be routed by another cable, typically TOS-Link or coax, into the speaker system.[41][52]

HDMI Ethernet Channel (HEC)

HDMI Ethernet Channel technology consolidates video, audio, and data streams into a single HDMI cable, and the HEC feature enables IP-based applications over HDMI and provides a bidirectional Ethernet communication at 100 Mbit/s.[43] The physical layer of the Ethernet implementation uses a hybrid to simultaneously send and receive attenuated 100BASE-TX type signals through a single twisted pair.[52][not in citation given][53][not in citation given]

Compatibility with DVI[edit]

HDMI is backward compatible with single-link Digital Visual Interface digital video (DVI-D or DVI-I, but not DVI-A). No signal conversion is required when an adapter or asymmetric cable is used, so there is no loss of video quality.[6](appx. C)

From a user's perspective, an HDMI display can be driven by a single-link DVI-D source, since HDMI and DVI-D define an overlapping minimum set of allowed resolutions and framebuffer formats to ensure a basic level of interoperability. In the reverse case, a DVI-D monitor has the same level of basic interoperability unless content protection with High-bandwidth Digital Content Protection (HDCP) interferes—or the HDMI color encoding is in component color space YCbCr instead of [RGB], which is not possible in DVI. An HDMI source, such as a Blu-ray player, may require an HDCP-compliant display, and refuse to output HDCP-protected content to a non-compliant display.[54] A further complication is that there is a small amount of display equipment, such as some high-end home theater projectors, designed with HDMI inputs but not HDCP-compliant.

Any DVI-to-HDMI adapter can function as an HDMI-to-DVI adapter (and vice versa).[citation needed] Typically, the only limitation is the gender of the adapter's connectors and the gender of the cables and sockets it is used with.

Features specific to HDMI, such as remote-control and audio transport, are not available in devices that use legacy DVI-D signalling. However, many devices output HDMI over a DVI connector (e.g., ATI 3000-series and NVIDIA GTX 200-series video cards),[6](appx. C)[55] and some multimedia displays may accept HDMI (including audio) over a DVI input. Exact capabilities beyond basic compatibility vary. Adapters are generally bi-directional.

Content protection (HDCP)[edit]

Main article: High-bandwidth Digital Content Protection

High-bandwidth Digital Content Protection (HDCP) is a newer form of digital rights management. Intel created the original technology to make sure that digital content followed the guidelines set by the Digital Content Protection group.

HDMI can use HDCP to encrypt the signal if required by the source device. CSS, CPRM and AACS require the use of HDCP on HDMI when playing back encrypted DVD Video, DVD Audio, HD DVD and Blu-ray Disc. The HDCP Repeater bit controls the authentication and switching/distribution of an HDMI signal. According to HDCP Specification 1.2 (beginning with HDMI CTS 1.3a), any system that implements HDCP must do so in a fully compliant manner. HDCP testing that was previously only a requirement for optional tests such as the "Simplay HD" testing program is now part of the requirements for HDMI compliance.[6](§9.2)[56][57] HDCP accommodates up to 127 connected devices with up to 7 levels, using a combination of sources, sinks and repeaters.[58] A simple example of this is several HDMI devices connected to an HDMI AV receiver that is connected to an HDMI display.[58]

Devices called HDCP strippers can remove the HDCP information from the video signal so the video can play on non-HDCP-compliant displays,[59] though a fair use and non-disclosure form must usually be signed with a registering agency before use.


There are five HDMI connector types. Type A/B are defined in the HDMI 1.0 specification, type C is defined in the HDMI 1.3 specification, and type D/E are defined in the HDMI 1.4 specification.

Type A
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.[6](§ There are 19 pins, with bandwidth to carry all SDTV, EDTV, HDTV, UHD, and 4K modes.[6](§6.3) It is electrically compatible with single-link DVI-D.[6](§4.1.3)
Type B
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 (3,840×2,400). It is electrically compatible with dual-link DVI-D, but has not yet been used in any products.[60] 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.[51](§§4.1.3,
Type C
This Mini connector is smaller than the type A plug, measuring 10.42 mm × 2.42 mm but has the same 19-pin configuration.[6](§§, It is intended for portable devices.[4][6](§4.1.1)[61] 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.[6](§ The type C Mini connector can be connected to a type A connector using a type A-to-type C cable.[6](§4.1.1)[61]
Type D
This Micro connector shrinks the connector size to something resembling a micro-USB connector,[61][62][63] measuring only 5.83 mm × 2.20 mm[6](fig. 4–9) 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.[64]
Type E
The Automotive Connection System[65] 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.[66]

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.[67]


An HDMI cable is composed of four shielded twisted pairs, with impedance of the order of 100 Ω (±15%), plus seven separate conductors. HDMI cables with Ethernet differ in that three of the separate conductors instead form an additional shielded twisted pair (with the CEC/DDC ground as a shield).[51](§HEAC-2.9)

Although no maximum length for an HDMI cable is specified, signal attenuation (dependent on the cable's construction quality and conducting materials) limits usable lengths in practice[68] and certification is difficult to achieve for lengths beyond 13 m.[70] HDMI 1.3 defines two cable categories: Category 1-certified cables, which have been tested at 74.5 MHz (which would include resolutions such as 720p60 and 1080i60), and Category 2-certified cables, which have been tested at 340 MHz (which would include resolutions such as 1080p60 and 4K30).[6](§4.2.6)[62][71] Category 1 HDMI cables are marketed as "Standard" and Category 2 HDMI cables as "High Speed".[4] This labeling guideline for HDMI cables went into effect on October 17, 2008.[72][73] Category 1 and 2 cables can either meet the required parameter specifications for interpair skew, far-end crosstalk, attenuation and differential impedance, or they can meet the required nonequalized/equalized eye diagram requirements.[6](§4.2.6) A cable of about 5 meters (16 feet) can be manufactured to Category 1 specifications easily and inexpensively by using 28 AWG (0.081 mm²) conductors.[68] With better quality construction and materials, including 24 AWG (0.205 mm²) conductors, an HDMI cable can reach lengths of up to 15 meters (49 feet).[68] Many HDMI cables under 5 meters of length that were made before the HDMI 1.3 specification can work as Category 2 cables, but only Category 2-tested cables are guaranteed to work for Category 2 purposes.[74]

As of the HDMI 1.4 specification, the following cable types are defined for HDMI in general:[75][76]

  • Standard HDMI Cable – up to 1080i and 720p
  • Standard HDMI Cable with Ethernet
  • Standard Automotive HDMI Cable
  • High Speed HDMI Cable – 1080p, 4K 30 Hz, 3D and deep color
  • High Speed HDMI Cable with Ethernet

A new certification program was introduced in October 2015 to certify that cables work at the 18 Gbit/s maximum bandwidth of the HDMI 2.0 specification.[77] In addition to expanding the set of cable testing requirements, the certification program introduces an EMI test to ensure cables minimize interference with wireless signals. These cables are marked with an anti-counterfeiting authentication label and are defined as:[78]

  • Premium High Speed HDMI Cable
  • Premium High Speed HDMI Cable with Ethernet

In conjunction with the HDMI 2.1 specification, a third category of cable was announced on January 4, 2017, called "48G".[79] Also known as Category 3 HDMI or "Ultra High Speed" HDMI, the cable is designed to support the 48 Gbit/s bandwidth of HDMI 2.1, supporting 4K, 5K, 8K and 10K at 120 Hz.[80] The cable is backwards compatible with the earlier HDMI devices, using existing HDMI type A, C and D connectors, and includes HDMI Ethernet.

  • Ultra High Speed HDMI Cable (48G Cable) – 4K, 5K, 8K and 10K at 120 Hz


An HDMI extender is a single device (or pair of devices) powered with an external power source or with the 5V DC from the HDMI source.[81][82][83] Long cables can cause instability of HDCP and blinking on the screen, due to the weakened DDC signal that HDCP requires. HDCP DDC signals must be multiplexed with TMDS video signals to comply with HDCP requirements for HDMI extenders based on a single Category 5/Category 6 cable.[84][85] Several companies offer amplifiers, equalizers and repeaters that can string several standard HDMI cables together. Active HDMI cables use electronics within the cable to boost the signal and allow for HDMI cables of up to 30 meters (98 feet);[81] those based on HDBaseT can extend to 100 meters; HDMI extenders that are based on dual Category 5/Category 6 cable can extend HDMI to 250 meters (820 feet); while HDMI extenders based on optical fiber can extend HDMI to 300 meters (980 feet).[82][83]


HDMI manufacturers pay an annual fee of US$10,000 plus a royalty rate of $0.15 per unit, reduced to $0.05 if the HDMI logo is used, and further reduced to $0.04 if HDCP is also implemented.[86] An alternative fee for HDMI manufacturers making fewer than 10,000 units per year is an annual fee of $5,000 with a royalty rate of $1 per unit.[86] The royalty only applies to final products and does not apply to products that are included in, or with, a licensed HDMI product that is already subject to the royalty.[86] For example, an HDMI cable sold directly to consumers is paid for by the cable manufacturer; however, if the cable manufacturer sells the HDMI cable to a HDTV manufacturer (who then includes the cable with an HDTV subject to the royalty) then the HDTV manufacturer pays only the royalty on the HDTV.[86]


HDMI devices are manufactured to adhere to various versions of the specification, in which each version is given a number or letter, such as 1.0, 1.2, or 1.4b.[6](p. III) Each subsequent version of the specification uses the same kind of cable but increases the bandwidth or capabilities of what can be transmitted over the cable.[6](p. III) A product listed as having an HDMI version does not necessarily mean that it has all features in that version,[87] since some HDMI features are optional, such as deep color and xvYCC (which is branded by Sony as "x.v.Color").[88][89] Note that since the release of HDMI 1.4, the HDMI Licensing LLC group (which oversees the HDMI standard) has banned the use of version numbers to identify cables.[90] Non-cable HDMI products, starting on January 1, 2012, may no longer reference the HDMI number, and must state which features of the HDMI specification the product implements.[91]

Version 1.0[edit]

HDMI 1.0 was released on December 9, 2002 and is a single-cable digital audio/video connector interface. The link architecture is based on DVI, using exactly the same video transmission format but sending audio and other auxiliary data during the blanking intervals of the video stream. HDMI 1.0 allows a maximum TMDS clock of 165 MHz (4.95 Gbit/s bandwidth per link), the same as DVI. It defines two connectors called Type A and Type B, with pinouts based on the Single-Link DVI-D and Dual-Link DVI-D connectors respectively, though the Type B connector was never used in any commercial products. HDMI 1.0 uses 8b/10b encoding for video transmission, giving it 3.96 Gbit/s of video bandwidth (1920 × 1080 or 1920 × 1200 at 60 Hz) and 8 channel LPCM/192 kHz/24-bit audio. HDMI 1.0 requires support for RGB video, with optional support for YCBCR 4:4:4 and 4:2:2 (mandatory if the device has support for YCBCR on other interfaces). Color depth of 10 bpc (30 bit/px) or 12 bpc (36 bit/px) is allowed when using 4:2:2 subsamling, but only 8 bpc (24 bit/px) color depth is permitted when using RGB or YCBCR 4:4:4. Only the Rec. 601 and Rec. 709 color spaces are supported. HDMI 1.0 allows only specific pre-defined video formats, including all the formats defined in EIA/CEA-861-B and some additional formats listed in the HDMI Specification itself. All HDMI sources/sinks must also be capable of sending/receiving native Single-Link DVI video and be fully compliant with the DVI Specification.[92]

Version 1.1[edit]

HDMI 1.1 was released on May 20, 2004 and added support for DVD-Audio.

Version 1.2[edit]

HDMI 1.2 was released on August 8, 2005 and added the option of One Bit Audio, used on Super Audio CDs, at up to 8 channels. To make HDMI more suitable for use on PC devices, version 1.2 also removed the requirement that only explicitly supported formats be used. It added the ability for manufacturers to create vendor-specific formats, allowing any arbitrary resolution and refresh rate rather than being limited to a pre-defined list of supported formats. In addition, it added explicit support for several new formats including 720p at 100 and 120 Hz and relaxed the pixel format support requirements so that sources with only native RGB output (PC sources) would not be required to support YCBCR output.[93](§6.2.3)

HDMI 1.2a was released on December 14, 2005 and fully specifies Consumer Electronic Control (CEC) features, command sets and CEC compliance tests.[93]

Version 1.3[edit]

HDMI 1.3 was released on June 22, 2006, and increased the maximum TMDS clock to 340 MHz (10.2 Gbit/s).[6][38][94] Like previous versions, it uses 8b/10b encoding, giving it a maximum video bandwidth of 8.16 Gbit/s (1920 × 1080 at 120 Hz or 2560 × 1440 at 60 Hz). It added support for 10 bpc, 12 bpc, and 16 bpc color depth (30, 36, and 48 bit/px), called deep color. It also added support for the xvYCC color space, in addition to the Rec. 601 and Rec. 709 color spaces supported by previous versions, and added the ability to carry metadata defining color gamut boundaries. It also optionally allows output of Dolby TrueHD and DTS-HD Master Audio streams for external decoding by AV receivers.[95] It incorporates automatic audio syncing (audio video sync) capability.[38] It defined cable Categories 1 and 2, with Category 1 cable being tested up to 74.25 MHz and Category 2 being tested up to 340 MHz.[6](§4.2.6) It also added the new type C Mini connector for portable devices.[6](§4.1.1)[96]

HDMI 1.3a was released on November 10, 2006, and had Cable and Sink modifications for type C, source termination recommendations, and removed undershoot and maximum rise/fall time limits. It also changed CEC capacitance limits, and CEC commands for timer control were brought back in an altered form, with audio control commands added. It also added the optional ability to stream SACD in its bitstream DST format rather than uncompressed raw DSD.[6]

Version 1.4[edit]

An adapter with HDMI (male) and DVI (female) connectors
An adapter with DVI and HDMI (female) connectors
Connector types for HDMI.
HDMI connector plugs (male): Type D (Micro), Type C (Mini), and Type A.
HDMI type A receptacle (female) connector

HDMI Connectors

HDMI (High-Definition Multimedia Interface) is a multi-pin connector for digital video and audio devices. It replaces the analog SCART connector.

HDMI is not format-dependant and can work with all common digital formats.

HDMI 1.3 can transmit uncompressed video at 340Mpixels/second and 8-channel uncompressed digital audio at 192kHz sample rate with 24 bits/sample.

The standard HDMI connector is defined as "Type A" and contains 19 pins (shown in the diagram below). The "Type B" HDMI connector is not yet in production — it is reserved for future higher-resolution devices.

Type A HDMI Connector

Pin Signal Assignment  Pin Signal Assignment
1 TMDS Data2+ 2 TMDS Data2 Shield
3 TMDS Data2– 4 TMDS Data1+
5 TMDS Data1 Shield 6 TMDS Data1–
7 TMDS Data0+ 8 TMDS Data0 Shield
9 TMDS Data0– 10 TMDS Clock+
11 TMDS Clock Shield 12 TMDS Clock–
13 CEC 14 Reserved (N.C. on device)
15 SCL 16 SDA
17 DDC/CEC Ground 18 +5 V Power
19 Hot Plug Detect 


HDMI was developed Hitachi, Matsushita (Panasonic), Philips, Silicon Image, Sony and Toshiba. It was officially released in 2002.

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