Source:- Google.com.pk
HDMI (High-Definition Multimedia Interface) is a proprietary audio/video interface for transferring uncompressed videodata 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.[1] 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.[2][3] 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.[4] 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 remote control handset.[5]
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.[6] 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 HDTV camcorders and digital still cameras in 2006.[7][8] As of January 8, 2013 (ten years after the release of the first HDMI specification), over 3 billion HDMI devices have been sold.[9][10][11]The HDMI founders are Hitachi, Matsushita Electric Industrial (Panasonic/National/Quasar), Philips, Silicon Image, Sony,Thomson, RCA and Toshiba.[12] Digital Content Protection, LLC provides HDCP (which was developed by Intel) for HDMI.[13]HDMI has the support of motion picture producers Fox, Universal, Warner Bros. and Disney, along with system operatorsDirecTV, EchoStar (Dish Network) and CableLabs.[1]
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.[14][15] 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.[15][16][17] 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.[15][16]
The first Authorized Testing Center (ATC), which tests HDMI products, was opened by Silicon Image on June 23, 2003, in California, United States.[18] The first ATC in Japan was opened by Panasonic on May 1, 2004, in Osaka.[19] The first ATC in Europe was opened by Philips on May 25, 2005, in Caen, France.[20] The first ATC in China was opened by Silicon Image on November 21, 2005, in Shenzhen.[21] The first ATC in India was opened by Philips on June 12, 2008, in Bangalore.[22] The HDMI website contains a list of all the ATCs.[23]
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.[24][25][26] HDMI has become the de facto standard for HDTVs, and according to In-Stat, around 90% of digital televisions in 2007 included HDMI.[24][27][28][29][30] In-Stat has estimated that 229 million HDMI devices were sold in 2008.[31] On April 8, 2008 there were over 850 consumer electronics and PC companies that had adopted the HDMI specification (HDMI Adopters).[32][33] On January 7, 2009, HDMI Licensing, LLC announced that HDMI had reached an installed base of over 600 million HDMI devices.[33] In-Stat has estimated that 394 million HDMI devices will sell in 2009 and that all digital televisions by the end of 2009 would have at least one HDMI input.[33]
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.[24][34]
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.[35] Ten companies were given a Technology and Engineering Emmy Award for their development of HDMI by the National Academy of Television Arts and Scienceson January 7, 2009.[36]
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.[37][38] 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.[38] There is no limit to the number of companies allowed in the HDMI Forum though companies must pay an annual fee of $15,000 with an additional annual fee of $5,000 for those companies who serve on the Board of Directors.[38] The Board of Directors will be made up of 11 companies who are elected every 2 years by a general vote of HDMI Forum members.[38] All future development of the HDMI specification will take place in the HDMI Forum and will be built upon the HDMI 1.4b specification.[38] 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.[12][37] From October 25, 2011, all development of the HDMI specification became the responsibility of the newly created HDMI Forum.[37]
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.[9][10][11] The day also marked the 10-year anniversary of the release of the first HDMI specification.[9][10][11]
§Specifications[edit]
See also: HDMI 1.3a Specifications
The HDMI specification defines the protocols, signals, electrical interfaces and mechanical requirements of the standard.[39] The maximum pixel clock rate for HDMI 1.0 was 165 MHz, which was sufficient to allow 1080p and WUXGA (1920×1200) at 60 Hz. HDMI 1.3 increased that to 340 MHz, which allows for higher resolution (such as WQXGA, 2560×1600) across a single digital link.[40] 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.[1]
§Audio/video[edit]
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.[2] 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)".[41] On July 15, 2013, the CEA announced the publication of CEA-861-F which is a standard that can be used by interfaces such as DVI, HDMI, and LVDS.[42] CEA-861-F adds the ability to transmit several Ultra HD video formats and additional color spaces.[42]
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.[43] 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).[44][45] The color spaces that can be used by HDMI are ITU-R BT.601, ITU-R BT.709-5 and IEC 61966-2-4.[44]
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.[16][46]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.[46] With version 1.3, HDMI allows lossless compressed audio streams Dolby TrueHD and DTS-HD Master Audio.[46] As with the YCbCr video, audio capability is optional. Audio return channel (ARC) is a feature introduced in the HDMI 1.4 standard.[47] "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.[47] 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.[47]
The HDMI standard was not designed to pass closed caption data (for example, subtitles) to the television for decoding.[48] 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 be viewed 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.
§Uncompressed video[edit]
Main article: Uncompressed video
The HDMI specification specifies several modes of uncompressed digital video. Although often HD video capable cameras include an HDMI interface for playback or even live preview, the image processor and the video processor of cameras usable for uncompressed video must be able to deliver the full image resolution at the specified frame rate inrealtime without any missing frames causing judder. Therefore usable uncompressed video out of HDMI is often called "Clean HDMI".
§Communication channel protocols[edit]
HDMI has three physically separate communication channels, which are the DDC, TMDS and the optional CEC.[49] HDMI 1.4 added ARC and HEC.[50][51]
§DDC[edit]
Main article: Display Data Channel
The Display Data Channel (DDC) is a communication channel based on the I²C bus specification.[52][53] 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.[49][52][53] 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).[54]
The DDC channel is actively used for High-bandwidth Digital Content Protection.
§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.[55] During the Video Data Period, the pixels of an active video line are transmitted.[55] 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.[55] The Control Period occurs between Video and Data Island periods.[55]
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.[55] 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.[56] 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.[57] Each Data Island Period can contain up to 18 Packets.[58] 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.[56] 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).[59][60] The Gamut Metadata Packet carries information on the color space being used for the current video stream and is required for xvYCC.[44][61][62]
§CEC[edit]
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,[63][64] 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).[65] CEC also allows for individual CEC-enabled devices to command and control each other without user intervention.[65]
It is a one-wire bidirectional serial bus that is based on the CENELEC standard AV.link protocol to perform remote control functions.[66] CEC wiring is mandatory, although implementation of CEC in a product is optional.[49] 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).[65][67][68][69][70] USB to CEC adapters exist that allow a computer to control CEC-enabled devices.[71][72][73][74]
Trade names for CEC are Anynet+ (Samsung), Aquos Link (Sharp), BRAVIA Link and BRAVIA Sync (Sony), HDMI-CEC (Hitachi), E-link (AOC), Kuro Link (Pioneer), INlink (Insignia), CE-Link and Regza Link (Toshiba), RIHD (Remote Interactive over HDMI) (Onkyo), RuncoLink (Runco International), SimpLink (LG), T-Link (ITT), HDAVI Control, EZ-Sync, VIERA Link (Panasonic), EasyLink (Philips), and NetCommand for HDMI (Mitsubishi).[75][76][77][78][79]
The following is a list of the most commonly used HDMI-CEC commands:
One Touch Play allows devices to switch the TV to use it as the active source when playback starts
System Standby enables users to switch multiple devices to standby mode with the press of one button
Preset Transfer transfers the tuner channel setup to another TV set
One Touch Record allows users to record whatever is currently being shown on the HDTV screen on a selected recording device
Timer Programming allows users to use the electronic program guides (EPGs) that are built into many HDTVs and set-top-boxes to program the timer in recording devices like PVRs and DVRs
System Information checks all components for bus addresses and configuration
Deck Control allows a component to interrogate and control the operation (play, pause, rewind etc.), of a playback component (Blu-ray or HD DVD player or a Camcorder, etc.)
Tuner Control allows a component to control the tuner of another component
OSD Display uses the OSD of the TV set to display text
Device Menu Control allows a component to control the menu system of another component by passing through the user interface (UI) commands
Routing Control controls the switching of signal sources
Remote Control Pass Through allows remote control commands to be passed through to other devices within the system
Device OSD Name Transfer transfers the preferred device names to the TV set
System Audio Control allows the volume of an AV receiver, integrated amplifier or preamplifier to be controlled using any remote control from a suitably equipped device(s) in the system
§ARC[edit]
HDMI 1.4 introduces a feature called ARC (Audio Return Channel) among other features.[50][51][80] Like HEC, the ARC feature, this feature use two pins from the connector: a previously unused pin and the hot plug detect pin.[80][81]
ARC is an audio link meant to replace other cables between the TV and the A/V receiver or speaker system.[50] This direction is used when the TV is the one that generates or receives the video stream instead of the other equipment.[50] 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.[50] Without ARC, the audio output from the TV needs to be routed by another cable, typically TOS-Link or coax, into the speaker system.
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.[2][3] 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.[4] 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 remote control handset.[5]
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.[6] 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 HDTV camcorders and digital still cameras in 2006.[7][8] As of January 8, 2013 (ten years after the release of the first HDMI specification), over 3 billion HDMI devices have been sold.[9][10][11]The HDMI founders are Hitachi, Matsushita Electric Industrial (Panasonic/National/Quasar), Philips, Silicon Image, Sony,Thomson, RCA and Toshiba.[12] Digital Content Protection, LLC provides HDCP (which was developed by Intel) for HDMI.[13]HDMI has the support of motion picture producers Fox, Universal, Warner Bros. and Disney, along with system operatorsDirecTV, EchoStar (Dish Network) and CableLabs.[1]
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.[14][15] 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.[15][16][17] 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.[15][16]
The first Authorized Testing Center (ATC), which tests HDMI products, was opened by Silicon Image on June 23, 2003, in California, United States.[18] The first ATC in Japan was opened by Panasonic on May 1, 2004, in Osaka.[19] The first ATC in Europe was opened by Philips on May 25, 2005, in Caen, France.[20] The first ATC in China was opened by Silicon Image on November 21, 2005, in Shenzhen.[21] The first ATC in India was opened by Philips on June 12, 2008, in Bangalore.[22] The HDMI website contains a list of all the ATCs.[23]
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.[24][25][26] HDMI has become the de facto standard for HDTVs, and according to In-Stat, around 90% of digital televisions in 2007 included HDMI.[24][27][28][29][30] In-Stat has estimated that 229 million HDMI devices were sold in 2008.[31] On April 8, 2008 there were over 850 consumer electronics and PC companies that had adopted the HDMI specification (HDMI Adopters).[32][33] On January 7, 2009, HDMI Licensing, LLC announced that HDMI had reached an installed base of over 600 million HDMI devices.[33] In-Stat has estimated that 394 million HDMI devices will sell in 2009 and that all digital televisions by the end of 2009 would have at least one HDMI input.[33]
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.[24][34]
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.[35] Ten companies were given a Technology and Engineering Emmy Award for their development of HDMI by the National Academy of Television Arts and Scienceson January 7, 2009.[36]
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.[37][38] 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.[38] There is no limit to the number of companies allowed in the HDMI Forum though companies must pay an annual fee of $15,000 with an additional annual fee of $5,000 for those companies who serve on the Board of Directors.[38] The Board of Directors will be made up of 11 companies who are elected every 2 years by a general vote of HDMI Forum members.[38] All future development of the HDMI specification will take place in the HDMI Forum and will be built upon the HDMI 1.4b specification.[38] 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.[12][37] From October 25, 2011, all development of the HDMI specification became the responsibility of the newly created HDMI Forum.[37]
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.[9][10][11] The day also marked the 10-year anniversary of the release of the first HDMI specification.[9][10][11]
§Specifications[edit]
See also: HDMI 1.3a Specifications
The HDMI specification defines the protocols, signals, electrical interfaces and mechanical requirements of the standard.[39] The maximum pixel clock rate for HDMI 1.0 was 165 MHz, which was sufficient to allow 1080p and WUXGA (1920×1200) at 60 Hz. HDMI 1.3 increased that to 340 MHz, which allows for higher resolution (such as WQXGA, 2560×1600) across a single digital link.[40] 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.[1]
§Audio/video[edit]
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.[2] 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)".[41] On July 15, 2013, the CEA announced the publication of CEA-861-F which is a standard that can be used by interfaces such as DVI, HDMI, and LVDS.[42] CEA-861-F adds the ability to transmit several Ultra HD video formats and additional color spaces.[42]
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.[43] 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).[44][45] The color spaces that can be used by HDMI are ITU-R BT.601, ITU-R BT.709-5 and IEC 61966-2-4.[44]
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.[16][46]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.[46] With version 1.3, HDMI allows lossless compressed audio streams Dolby TrueHD and DTS-HD Master Audio.[46] As with the YCbCr video, audio capability is optional. Audio return channel (ARC) is a feature introduced in the HDMI 1.4 standard.[47] "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.[47] 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.[47]
The HDMI standard was not designed to pass closed caption data (for example, subtitles) to the television for decoding.[48] 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 be viewed 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.
§Uncompressed video[edit]
Main article: Uncompressed video
The HDMI specification specifies several modes of uncompressed digital video. Although often HD video capable cameras include an HDMI interface for playback or even live preview, the image processor and the video processor of cameras usable for uncompressed video must be able to deliver the full image resolution at the specified frame rate inrealtime without any missing frames causing judder. Therefore usable uncompressed video out of HDMI is often called "Clean HDMI".
§Communication channel protocols[edit]
HDMI has three physically separate communication channels, which are the DDC, TMDS and the optional CEC.[49] HDMI 1.4 added ARC and HEC.[50][51]
§DDC[edit]
Main article: Display Data Channel
The Display Data Channel (DDC) is a communication channel based on the I²C bus specification.[52][53] 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.[49][52][53] 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).[54]
The DDC channel is actively used for High-bandwidth Digital Content Protection.
§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.[55] During the Video Data Period, the pixels of an active video line are transmitted.[55] 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.[55] The Control Period occurs between Video and Data Island periods.[55]
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.[55] 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.[56] 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.[57] Each Data Island Period can contain up to 18 Packets.[58] 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.[56] 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).[59][60] The Gamut Metadata Packet carries information on the color space being used for the current video stream and is required for xvYCC.[44][61][62]
§CEC[edit]
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,[63][64] 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).[65] CEC also allows for individual CEC-enabled devices to command and control each other without user intervention.[65]
It is a one-wire bidirectional serial bus that is based on the CENELEC standard AV.link protocol to perform remote control functions.[66] CEC wiring is mandatory, although implementation of CEC in a product is optional.[49] 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).[65][67][68][69][70] USB to CEC adapters exist that allow a computer to control CEC-enabled devices.[71][72][73][74]
Trade names for CEC are Anynet+ (Samsung), Aquos Link (Sharp), BRAVIA Link and BRAVIA Sync (Sony), HDMI-CEC (Hitachi), E-link (AOC), Kuro Link (Pioneer), INlink (Insignia), CE-Link and Regza Link (Toshiba), RIHD (Remote Interactive over HDMI) (Onkyo), RuncoLink (Runco International), SimpLink (LG), T-Link (ITT), HDAVI Control, EZ-Sync, VIERA Link (Panasonic), EasyLink (Philips), and NetCommand for HDMI (Mitsubishi).[75][76][77][78][79]
The following is a list of the most commonly used HDMI-CEC commands:
One Touch Play allows devices to switch the TV to use it as the active source when playback starts
System Standby enables users to switch multiple devices to standby mode with the press of one button
Preset Transfer transfers the tuner channel setup to another TV set
One Touch Record allows users to record whatever is currently being shown on the HDTV screen on a selected recording device
Timer Programming allows users to use the electronic program guides (EPGs) that are built into many HDTVs and set-top-boxes to program the timer in recording devices like PVRs and DVRs
System Information checks all components for bus addresses and configuration
Deck Control allows a component to interrogate and control the operation (play, pause, rewind etc.), of a playback component (Blu-ray or HD DVD player or a Camcorder, etc.)
Tuner Control allows a component to control the tuner of another component
OSD Display uses the OSD of the TV set to display text
Device Menu Control allows a component to control the menu system of another component by passing through the user interface (UI) commands
Routing Control controls the switching of signal sources
Remote Control Pass Through allows remote control commands to be passed through to other devices within the system
Device OSD Name Transfer transfers the preferred device names to the TV set
System Audio Control allows the volume of an AV receiver, integrated amplifier or preamplifier to be controlled using any remote control from a suitably equipped device(s) in the system
§ARC[edit]
HDMI 1.4 introduces a feature called ARC (Audio Return Channel) among other features.[50][51][80] Like HEC, the ARC feature, this feature use two pins from the connector: a previously unused pin and the hot plug detect pin.[80][81]
ARC is an audio link meant to replace other cables between the TV and the A/V receiver or speaker system.[50] This direction is used when the TV is the one that generates or receives the video stream instead of the other equipment.[50] 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.[50] Without ARC, the audio output from the TV needs to be routed by another cable, typically TOS-Link or coax, into the speaker system.
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