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Forcing ADV7626 CP freerun causes a blip in black-level output

Question asked by JeremyM on Jul 27, 2016
Latest reply on Oct 17, 2016 by JeyasudhaMuthuPerumal


I have a video processing sequence with essentially does the following:

 

1) A video change occurs on the RX side of the ADV7626 - we immediately 'mute' the TX output by setting the black level output (TX Main 0x9e bit4) and set the appropriate VFE input RGB/YUV (TX Main 0x16 bit0)

2) The output is now black as expected - next we put the RX side of the ADV7626 into forced freerun - set CP 0xBF bit0

3) The TX output momentarily shows the freerun color leaked through - it lasts about .5 to 1 seconds then goes back to black; I would have expected the TX output to remain 'muted' with the black-level.

4) Once the new input format is locked we exit forced freerun - again the black-level on the TX side leaks through a blip of freerun color and then goes black again.

5) We finallly 'un-mute' the TX output by clearing the black-level setting.

 

I am trying to understand why the force-freerun seems to override the TX black-level and leak color through momentarily?  Our freerun color is intentionally NOT black - so it is very visible.  I am looking for some guidance as to if this is an invalid series of steps to take, or if I am missing some un-documented connection between the CP freerun generator and the TX black-level generator?

 

thanks,

jeremy

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