[Paul Russell]

If the source was originated as progressive at 29.97 then you will end up with a repeated field within each interlaced frame, except that one field will be odd, one even, the picture content shall be the same essentially, you cannot alter the timebase of the capture as it were, just of the display pattern. In essence 29.97p footage will not have the smoothness of 59.94i, even if the re-encoded material is technically complient for interlaced timebase.

Think of it this way, if you had telecined film, the source film is only ever going to have the motion of 24p. Thats why film still looks different from video, even with a 59.94i telecine.

If your source footage was 59.94p (rare) then your conversion process would essentially chuck the even or odd lines away for the appropriate field and each of your two fields would have captured a slightly different moment, and so you would have the smoothness of motion expected from broadcast video, as well as the now correct scan pattern, but the key is in the source material. You cannot put in what wasn’t captured.

Another handy tool for these kind of jobs is the free app JEC-deinterlacer, which is often more transparent in use than compressor etc. I’m not keen on the qt or adobe routes as they sometime try to enforce things like gamma correction or certain colour profiles, they can sork well but you really need to be up early and on the ball.