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AR# 55221

LogiCORE IP AXI Video Direct Memory Access - Low frame rate/choppy video


I have set up the AXI VDMA as a simple triple frame buffer, but I am seeing what appears to be very low frame rate video on the screen.

This can also be described as 'choppy' video.

What is causing this? How do I fix it?


This issue can be caused by improper Genlock setup. Genlock should be set up as follows for a typical frame buffer:

Hardware Settings

  • S2MM side should be the genlock master
  • MM2S side should be the genlock slave
  • Include Internal Genlock should be enabled

Software (Register) Settings

    • GenlockEn bit should be set to 1
    • GenlockSrc bit should be set to 1*

Note: There is a known issue in the driver (driver versions 4.01.a and 4.02.a) where it does not set the MM2S GenlockSrc bit properly.

You must use direct register writes to access this bit. See (Xilinx Answer 53331) for more information.

Also, be sure to set up the frame sync sources properly.

See (Xilinx Answer 53281) for more information on setting up frame synchronization.

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AR# 55221
Date Created 03/28/2013
Last Updated 02/03/2016
Status Active
Type General Article
  • Video DMA
  • AXI Video Direct Memory Access
  • AXI Video DMA
  • AXI Video DMA