iMovie 4K resolution to Keynote – apparent loss of resolution I exported a 4k resolution video from iMovie on my MacBook Pro. I imported it into Keynote in order to crop it. I noticed that upon exporting from Keynote, the resolution of the video was markedly reduced. 

In Keynote, I had exported the cropped video using File → Export To → Movie. Upon export, the resolution field only gave me 720p, 1080p, and Custom. I clicked on Custom. This gave me three compression types: H.264, Apple ProRes 422, and Apple ProRes 4444. I tried saving the cropped video using each of these three options. However, in each case, the video appeared to be reduced in quality (presumably resolution).

My question is: How can I crop a 4K video in Keynote and export it without reducing quality/resolution?
I had the same problem. I changed the dimensions to 2160×3840 and exported and the quality was excellent. Hope this helps.