See the finished product: • Video
Make a picture slideshow with a single terminal command. The command below will take all .jpg pics in a directory and cycle through them one every four seconds (that is, framerate of 0.25):
cat *.jpg | ffmpeg -framerate 0.25 -f image2pipe -i - output.mkv
Or, add a music track as well:
cat *.jpg | ffmpeg -framerate 0.25 -f image2pipe -i SONG.mp3 -acodec copy -output.mkv