How can I determine the refresh rate of input video in HDMI-GR mode of ADV7441A?

Document created by Patrick.Aherne on Jan 4, 2011
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By manipulating the read back parameters Block Length (BL) and Line count Field (LCF) information provided by STDI we can work out the vertical refresh rate as follows:


(Block Length x XTAL Period)/8 = T line of video


T line of video x LCF = T frame of video. 


(1 / T frame of video) = Refresh rate.


E.g for 720p60 BL readback ~ 5082. LCF ~ 750. XTAL Period = 1/28.63636MHz = 34.9ns


=> Tline of video = (5082 x 34.9ns) / 8 = 22.22us. 


T frame of video = 22.22us x 750 = 16.667ms


=> Refresh Rate = 60Hz