I generally like Compressor but this is weird so I am clearly missing something.
I'm using Compressor 3. I have several QT movies of old VHS tapes (interlacing was removed in FCP) and the frame rate is 29.97. When I play them in the QT Player, they look great. No interlacing, no issues.
What I want to do is just compress them down a little bit (for archival purposes) and keep all settings the same. So I used ProRes Proxy and outputted new clips. The new clips show interlacing like crazy! I didn't change any settings; just kept everything same as source so I'm not sure what happened.
I understand how to deinterlace a clip in Compressor, but what do you do if the original clip is already deinterlaced, but the output adds back the interlacing?
Compressor is likely misinterpreting your source file. When you drop the file into Compressor, check the Inspector and make sure it shows Progressive. Then apply your preset, and make sure in both Video encoder settings and Frame Controls that it all says Progressive, and not Upper Field or Lower Field or Interlaced.