High-definition multimedia interface (HDMI) system architecture is defined to consist of Sources and Sinks. A given device may have one or more high-definition multimedia interface HDMI inputs and one or more HDMI high-definition multimedia interface outputs. Each High-definition multimedia interface HDMI input on these devices shall follow all of the rules for an High-definition multimedia interface HDMI Sink and each HDMI High-definition multimedia interface output shall follow all of the rules for an HDMI High-definition multimedia interface Source.
As shown in "HDMI Block Diagram" Figure, the HDMI - high-definition multimedia interface - cable and connectors carry four differential pairs that make up the TMDS data and clock channels. These channels are used to carry video, audio and auxiliary data. In addition, HDMI high-definition multimedia interface carries a VESA DDC channel. The DDC is used for configuration and status exchange between a single Source and a single Sink. The optional CEC protocol provides high-level control functions between all of the various audiovisual products in a user’s environment.
Audio, video and auxiliary data is transmitted across the three TMDS data channels. A TMDS clock, typically running at the video pixel rate, is transmitted on the TMDS clock channel and is used by the receiver as a frequency reference for data recovery on the three TMDS data channels. At the source, TMDS encoding converts the 8 bits per TMDS data channel into the 10 bit DC-balanced, transition minimized sequence which is then transmitted serially across the pair at a rate of 10 bits per TMDS clock period.
Video data can have a pixel size of 24, 30, 36 or 48 bits. Video at the default 24-bit color depth is carried at a TMDS clock rate equal to the pixel clock rate. Higher color depths are carried using a correspondingly higher TMDS clock rate. Video formats with TMDS rates below 25MHz (e.g. 13.5MHz for 480i/NTSC) can be transmitted using a pixel-repetition scheme. The video pixels can be encoded in either RGB, YCBCR 4:4:4 or YCBCR 4:2:2 formats.
In order to transmit audio and auxiliary data across the TMDS channels, HDMI - high definition multimedia interface - uses a packet structure. In order to attain the higher reliability required of audio and control data, this data is protected with a BCH error correction code and is encoded using a special error reduction coding to produce the 10-bit word that is transmitted.
Basic audio functionality consists of a single IEC 60958 L-PCM audio stream at sample rates of 32kHz, 44.1kHz or 48kHz. This can accommodate any normal stereo stream. Optionally, HDMI - high definition multimedia interface - can carry such audio at sample rates up to 192KHz and with 3 to 8 audio channels. HDMI - high definition multimedia interface - can also carry an IEC 61937 compressed (e.g. surround-sound) audio stream at bit rates up to 24.576Mbps. HDMI - high definition multimedia interface - can also carry from 2 to 8 channels of One Bit Audio and a compressed form of One Bit Audio called DST.
The DDC is used by the Source to read the Sink’s Enhanced Extended Display Identification Data (E-EDID) in order to discover the Sink’s configuration and/or capabilities.
As shown in "HDMI Block Diagram" Figure, the HDMI - high-definition multimedia interface - cable and connectors carry four differential pairs that make up the TMDS data and clock channels. These channels are used to carry video, audio and auxiliary data. In addition, HDMI high-definition multimedia interface carries a VESA DDC channel. The DDC is used for configuration and status exchange between a single Source and a single Sink. The optional CEC protocol provides high-level control functions between all of the various audiovisual products in a user’s environment.
Audio, video and auxiliary data is transmitted across the three TMDS data channels. A TMDS clock, typically running at the video pixel rate, is transmitted on the TMDS clock channel and is used by the receiver as a frequency reference for data recovery on the three TMDS data channels. At the source, TMDS encoding converts the 8 bits per TMDS data channel into the 10 bit DC-balanced, transition minimized sequence which is then transmitted serially across the pair at a rate of 10 bits per TMDS clock period.
Video data can have a pixel size of 24, 30, 36 or 48 bits. Video at the default 24-bit color depth is carried at a TMDS clock rate equal to the pixel clock rate. Higher color depths are carried using a correspondingly higher TMDS clock rate. Video formats with TMDS rates below 25MHz (e.g. 13.5MHz for 480i/NTSC) can be transmitted using a pixel-repetition scheme. The video pixels can be encoded in either RGB, YCBCR 4:4:4 or YCBCR 4:2:2 formats.
In order to transmit audio and auxiliary data across the TMDS channels, HDMI - high definition multimedia interface - uses a packet structure. In order to attain the higher reliability required of audio and control data, this data is protected with a BCH error correction code and is encoded using a special error reduction coding to produce the 10-bit word that is transmitted.
Basic audio functionality consists of a single IEC 60958 L-PCM audio stream at sample rates of 32kHz, 44.1kHz or 48kHz. This can accommodate any normal stereo stream. Optionally, HDMI - high definition multimedia interface - can carry such audio at sample rates up to 192KHz and with 3 to 8 audio channels. HDMI - high definition multimedia interface - can also carry an IEC 61937 compressed (e.g. surround-sound) audio stream at bit rates up to 24.576Mbps. HDMI - high definition multimedia interface - can also carry from 2 to 8 channels of One Bit Audio and a compressed form of One Bit Audio called DST.
The DDC is used by the Source to read the Sink’s Enhanced Extended Display Identification Data (E-EDID) in order to discover the Sink’s configuration and/or capabilities.
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