ADV7182A jitter

We are doing a proof-of-concept design prior to committing to production.  With parts going EOL, we are re-designing a display unit that is required to accept analog camera inputs along with its other duties.  We lashed an EVAL-ADV7182A board to a Kiel ARM development board that uses the processor we intend to use and also has an LCD. 

We are capturing the digital output from the ADV7182A and placing it into buffers for subsequent rendering.  This is a dual core ARM so one core is dedicated to capturing the video while the other one does the rendering. 

Rendering is slightly slower than capturing since it must transform YCrCb into RGB, handle interlacing and rotate the image 90 degrees. 

All this seems to work.  Here is my issue.

I am getting a one or two line jitter on the screen if the input is NTSC.  If its PAL the jitter doesn’t appear.

I don’t get any jitter if I let the ADV7182A free run with a test pattern.  It only happens with NTSC video on any of the analog inputs using either a camera or a video test generator.

I have played with numerous register settings and I can’t seem to get rid of this jitter.  Is there something inherent in the ADV8172A that makes this happen?