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DM8167 Video Output

Roger Leopold
Prodigy 50 points

A little confused on the video output format.  We have implemented a design that connects Vout[0] to an AD9889B HDMI Transmitter.  We want to run at 720p60.  We have VOUT[0]_G_Y_YC[9:2] from the DM8167 connected to the Y[7:0] input of the AD9889B.  We have VOUT[0]_B_CB_C[9:2] connected to the Cb/Cr[7:0] input of the AD9889B.  The AD9889B is configured for "YCbCr 422 Format, 16 bits with Embedded Syncs".  Is this a valid output format from the DM8167?  We do not have the code up and running yet to test this but I want to be ahead of the curve.

It seems like the "more correct" or better quality video would be to run these devices in 20-bit mode but it also seems like the interenal DM8167 processing is only done on 16-bits - is this correct?  Would the video be better quality if we ran the output of the DM8167 at 20-bits verses 16-bits?  Or are these extra 4 bits "created"?  The AD9889B can be configured to run in 20-bit mode as well.

Thank you.

  • 0
    TI__Mastermind 43875 points

    Yes, this is a valid connection.

    Even though the frame buffers are limited to 8 bit per color channel all the processing in the video output paths are one to higher resolution so if you are scaling, blending, doing de-interlacing or noise reduction, or using the color space converters etc... then you will potentially see a slight improvement in quality.

    You will see more of an improvement in video quality by using 24 bit 444 mode if you are not using the other VOut[0] signals for other purposes. Depending on the ADI capabilities this may require using discrete syncs.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Prodigy 50 points

    Great.  We'll verify once we get things up and running.  Thank you for your help.