User:Gufengsheng

�Digital interface defined around DVI 1.0 that transmits video and audio on the same physical channel. 􀂋Interface defined for use in the consumer market space. 􀁺Requires separate licensing from that of DDWG’s DVI. 􀁺Allows DVI/HDMI products to be sold in consumer products 􀂋Supports the use of HDCP copy protection. 􀂋Utilizes VESA’s Display Data Channel to read E-EDID from a display. 􀂋Defines a different connector from that used on DVI. 􀂋Supports optional CEC (Consumer Electronics Control), which allows high level control of all A/V products in a user environment. DVI 1.0: The Physical Interface 􀂋Digital Visual Interface (DVI) was developed by a group called the Digital Display Working Group or DDWG for the PC market. 􀂋The interface is a high speed digital serial interface based on Transition Minimized Differential Signaling or TMDS. 􀁺Source synchronous architecture. Uses a separate channel to transmit the clock. 􀁺Used to provide variable data rates to handle the various VESA supported display resolutions. 􀂋A complete connection from the source to the sink devices uses three data channels (RGB/YCbCr) and a clock. HDMI = DVI + Audio 􀂋Using the DVI physical link to transmit video/graphics 􀂋Audio is added as a logical layer to the DVI phy. 􀁺Digital audio processed into packets of data 􀁺These packets are scheduled for transmission during existing horizontal and vertical blanking times within a frame. 􀂋In addition, HDMI implements a packet called an infoFrame. 􀁺InfoFramesare structures defined in the EIA-861B specification 􀁺EIA-861B is spec for DTV and uncompressed high speed digital interfaces. What is HDMI Data? 􀂋There are three categories of data that is transmitted via an HDMI link. 􀁺Video Data –Video pixel data (8b data encoded to 10b), and Guard Bands (fixed 10b pattern) 􀁺Data Island –Packet data, which can be either audio samples or Infoframes(TERC4 encoded, 4b encoded to 10b) as well as its own Guard Band (fixed 10b pattern). 􀁺Control –Control period coding, in which we find HSYNC, VSYNC (2b to 10b encoding) and a Preamble (used to determine whether subsequent data is video or data island) Transmission of Video/Graphics 􀂋HDMI transmits 24bit pixel data via three separate channels. 􀂋Pixel rates supported are 25MHz to 165MHz. 􀁺This is exactly the same as single link DVI 1.0 􀂋Also supports video rates below 25MHz e.g. 13.5MHz for 480i NTSC signals. 􀁺Achieves this through a “pixel-repetition”scheme. 􀂋Can handle pixel data in RGB, YCbCr(4-4-4), YCbCr(4-2-2) formats. 􀁺In all cases 24 bits of data per pixel clock are transmitted. Transmission of Audio 􀂋Basic Audio is provided via an IEC60958 audio stream at 33kHz, 44.1kHz, or 48kHz. 􀁺Accommodates any normal stereo audio stream. 􀂋Optionally this stream can be sent as a single channel at 192kHz. 􀂋Can support IEC61937 compressed formats as found in surround-sound, Dolby Digital, etc. at rates up to 192kHz. Infoframes and HDMI 􀂋EIA/CEA-861B specifies a special packet called an infoframe 􀂋HDMI sources and sinks are expected to use two basic infoframes. 􀁺AVI (Auxiliary Video Information) Infoframe 􀂋Communicates Colorimetry, Picture aspect ratio, Pixel-Repetition factor, RGB or YCbCrindicator, and others specified within 861B standard. 􀁺Audio Infoframe 􀂋Communicates, Channel count, Coding Type, Sample size, Sample frequency, Channel allocation and other audio specific information. 􀂋There are other types of infoframes that are supported by the 861B standard, but are optional with respect to HDMI specification.