When capturing DV downconverted from the cam there are 2-3 lines along the top that are not captured resulting in a black line. It is easy to preset a crop in track motion to crop these out (even though i would prefer not to lose 2-3 lines of resolution!) and it is fine unless you add any filters such as a blur then the pixels interpolate into the frame causing the top to be significantly darker.

So besides cropping and then unnecessarily rendering the clip, what process might I be able to do to only crop those 2-3 lines and make it so the filters dont "see" them in their calculation?