I’ll have to try this! I was under the impression that it was lossy in Quicktime X. I’ve been going back to Quicktime 7 for this option (which has apparantly finally stopped working in Catalina, but the Apple downloadable version originally released for Snow Leopard works fine under Mojave still!). I’ve been using Quicktime 7 Pro to do all kinds of things FFMPEG can do, not only cropping losslessly but also removing, extracting and changing the soundstream. It’s simpler for me than having to remember the commands :)