How to crop a video that ended up slightly larger than planned:
ffmpeg -i b3b-2.mp4 -vf crop=900:596:2:0 -an b3b-2-intermediate.mp4
How to scale up a video to a specific constrainted size (in this case, height)
ffmpeg -i c4d-1.mp4 -vf scale=h=’min(600\, ih*3/2):w=-1′ -an c4d-2.mp4