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ADV7842 HDMI Incorrect Video Measurment

Question asked by MatthewDSE on Dec 17, 2013
Latest reply on Dec 18, 2013 by GuenterL

Hello,

 

We are using the ADV7842 as a front end digital video decoder.  For determining the input HDMI resolution I have been reading the line width (hdmi registers 0x7 and 0x8) and field height (hdmi registers 0x9 and 0xA).  However, for some resolutions the values are incorrect. Can anyone help explain why these registers are not giving the correct results?

 

Here are some  resolutions I have tested and the values read from the line width and line height registers.  Notice the line with and line height are correct for the SVGA and XGA resolutions but incorrect for the others.

 

Resolution               line width, line height

800x600 60hz          800, 600

1024x768 60hz        1024, 768

1152,864  60hz        1280, 960

1280x768 60hz        1280, 960

1280x1024 60hz       1680, 1050

 

Sincerely,
Matthew

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