It's because of the color profile used by avfoundation, quicktime requires a specific profile. You should be able to open the file with mpv/mplayerX or VLC. If

It's because of the color profile used by avfoundation, quicktime requires a specific profile. You should be able to open the file with mpv/mplayerX or VLC. If you want to open it with quicktime or imovie, you need to reencode the file with a specific color space, more info on the ffmpeg wiki[0] (Using -pix_fmt yuv420p should be sufficient). Sadly, you cannot record directly in yuv420p with avfoundation. [0] https://trac.ffmpeg.org/wiki/Encode/H.264#AppleQuicktime https://trac.ffmpeg.org/wiki/Encode/H.264#AppleQuicktime