I'm using ffmpeg 4.4 to make a slideshow video that is lossless from png images like so:
ffmpeg -framerate 30 -i 'image_%05d.png' -c:v libx264 -crf 0 out.mp4
The only thing is that in macOS Finder, preview is not available. Normally the video icon is a frame from the video and you can play it in Finder. The video generated with the command however just shows my default video player icon and you cannot preview. If you open in VLC it plays fine. Adding -pix_fmt yuv420p shows the preview, but this degrades the video quality.