Photo and video

Image viewers

• FlowVision - Image viewer and organizer for macOS
• qView - Minimalist image viewer

Image editing

• Affinity Studio - Free all design and photo editing tools
• Pixelmator Pro - Image editing made easy
• Procreate - The most powerful and intuitive digital illustration app

Video players

• IINA - The modern video player for macOS
• Elmedia Player - Video player for Mac

Video editing

• Davinci Resolve - Free video editor for Windows/macOS
• LumaFusion - Professional Editing Reimagined for Mobile
• Final Cut Pro - best for mac
• iMovie - free video editor for mac

Screen recorders

• Kap - An open-source screen recorder built with web technology.
• Screen Studio - Beautiful Screen Recordings in Minutes

FFmpeg for iMovie / Apple-friendly export

You need to include the argument -pix_fmt yuv420p to generate H.264 content for Apple software/devices, and a bunch of other decoders that don’t handle yuv444p.

ffmpeg -i input.avi -pix_fmt yuv420p output.mp4

Apple added ProRes support sometime in late 2014 since iMovie 10 you can use follow code:

ffmpeg -i input.avi -c:v prores -c:a pcm_s16le output.mov

Formats compatible with macOS Catalina:

Video formats:

• Apple Animation Codec
• Apple Intermediate Codec
• Apple ProRes
• AVCHD (including AVCCAM, AVCHD Lite, and NXCAM)
• DV (including DVCAM, DVCPRO, and DVCPRO50)
• H.264
• HDV
• HEVC
• iFrame
• Motion JPEG (OpenDML only)
• MPEG-4 SP
• Photo JPEG
• XAVC-S

Container formats: 3GP, AVI, M4V, MOV (QuickTime) and MP4 Audio formats: AAC, AIFF, BWF, CAF, MP3, MP4, RF64 and WAV

More information about incompatible media in iMovie for macOS