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ADV7842 Input to Output mapping options

Question asked by ohmslaw on Mar 23, 2011
Latest reply on Mar 23, 2011 by ohmslaw



I am designing the ADV7842 into a device that must accept the following video formats.


Composite NTSC

PC Graphics SVGA (800x600)

HDMI, also from Laptop output (800x600)


I am having a little bit of trouble figuring out what inputs can map to the variety of output formats available. A lot of this is due to my lack of experience working with video, but also the documentation doesn’t seem to spell it out anywhere.


The ADV7842 output will feed into an FPGA that would preferably like to see YCbCr 4:2:2, but obviously there is some configurability available. It would be desirable if all three inputs could share the same output format. I will try to ask a few questions that can be answered directly.


1.) Is the ADV7842 able to take PC Graphics or HDMI inputs and map to the “8-bit ITU656 Mode 0”output? (I guess no as there is no interlacing or frame buffer shown anywhere in the block diagrams.)


2.) Can both the VGA or HDMI inputs be mapped to the “16-bit SDR 4:2:2 Mode 0” output?


3a.) Can the Composite NTSC input also be mapped to the “16-bit SDR 4:2:2 Mode 0” output?


3b.) If so, is the ‘interlace to progressive scan conversion’ required to do so?


4.) Is there any reason to prefer the 24-bit 4:4:4 output modes to the 4:2:2 output modes as far as the configuration of the ADV7842 is concerned?


Thanks so much for any insight you can provide!