24400 628 800 u00d7 600 105660 hz 20677 806 1024 u00d7 768 134460 hz 15631 1066 1280 u00d7 1024 1696______________________________________ thus for exemplary values of 31778 50mhz clocks in twenty lines and 525 lines per frame the look up table determines a resolution of 640 u00d7 480 with a number n of pixel clocks per line of 800 the expected width in pixels of the active video region 11 see fig1 d is initially set at the horizontal component of the resolution e g 640 it is to be understood that such number n is an initial guess and that a range of initial n values will work due to the iterative corrective nature of the present invention accordingly n may be determined in other ways such as by multiplying the horizontal resolution by a constant slightly larger than 1 0 it is also to be understood that the preferred look up table will cover modes from 640 u00d7 480 to 1600 u00d7 1200 resolution and from 60 hz to 100 hz frame refresh rates moreover other ways of determining the resolution are possible such as by using the number of lines per frame to determine the vertical and horizontal resolution digitization of the analog video data signals occurs based on the n pixel clocks per line referring to the pll 20 the vco 50 generates the pixel clock signal and the microcontroller 16 sets the counter 22 to generate a feedback pulse i e line advance signal once.