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1、视频信号分类及介绍,Color Spaces,RGB-most basic of the color spacesYCbCr-digital representation of the video signaldeveloped as part of ITU-R BT.601Nominal ranges of:Y=16-235Cb,Cr=16-240YPbPr-analog representation of the video signal,RGB to YCbCr-HDTVassumes 8-bit data with a 16235 nominal rangeYPbPr Generati
2、on-HDTVassumes 10-bit DAC with an output range of 01.305V,Video Signals,Composite video:=y+u*sin wsct+v*cos wsctS video:luma=ychroma=u*sin wsct+v*cos wsctComponent video:luma=yPb=1.146*u Pr=0.813*v RGB,Composite Video Standards NTSC,PAL,SECAM,NTSC:Color is quadrature-modulated by subcarrier.Short bu
3、rst of subcarrier at the beginning of each line used as reference for amplitude(saturation)and phase(hue).PAL:Similar to NTSC.Burst phase alternates from line to line.SECAM:Color is frequency modulated.,Composite Video Signal(Example:NTSC),Composite Frequency Spectrum(Example:NTSC),Many formats exis
4、t with different resolutions and frame(refresh)ratesAlways 3 color components:Red,Green,BlueSynchronization is carried via TTL-style dedicated HSYNC,VSYNC signalsHSYNC:1 pulse per lineVSYNC:1 pulse per frame(field),Popular PC Graphics Formats,A total of 18 formats exists,defined by ATSC(Advanced Tel
5、evision Systems Committee),1080I(1080 active lines,interlaced)and 720P(720 lines,progressive)are two of the most popular formats Both result in same same pixel(sampling)clock frequency of 74.25MSPS(calculation below)Based on this an 80MSPS DAC is sufficient for HDTV,Popular Component Video Formats,HDTV,SDTV,RGB Component Video,NOTE:Trilevel sync shown is for HDTV;bilevel(negative sync)for SDTV,YPbPr Component Video(HDTV),NOTE:Trilevel sync shown is for HDTV;bilevel(negative sync)for SDTV,视频信号分类及介绍,
