it may be that ae is misinterpreting whether the footage is interlaced or progressive. if you know which it is you can see if ae is interpreting it correctly. select the footage in the project window. then choose file>interpret footage>main… check the ‘separate fields’ option to see if it has the correct interpretation (lower, upper or none). if you don’t know the correct interpretation, pick one and see if it makes any difference.
also make sure that the pixel aspect ratio is correct too, that will make a difference when you convert from pal or square pixel to ntsc.
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW