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

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