FFMPEG with Brew (dependencies)
#Install FFMpeg with Brew#
brew install ffmpeg --with-fdk-aac --with-sdl2 --with-freetype --with-libass --with-libquvi --with-libvorbis --with-libvpx --with-opus --with-x265 --enable-libtheora --enable-libvorbis
brew install ffmpeg2theora
#Extract images from video file#
-t is the start time (can be expressed as 00:00:00, or whole numbers representing seconds)
-ss is how long to extract (can be expressed as 00:00:00, or whole numbers representing seconds)
-r is step sequence, -r 1 is equal to "for every one second" (can be expressed as 00:00:00, or whole numbers representing seconds)
ffmpeg -t 00:00:05 -ss 1 -i videofile.mov -r 1 extracted_image-%03d.png
https://superuser.com/questions/1357459/add-poster-frame-artwork-to-mp4
ffmpeg -i video.mp4 -i image.png -map 1 -map 0 -c copy -disposition:0 attached_pic out.mp4