ffmpeg: Making a Picture Slideshow without a Video Editor!

See the finished product: https://youtu.be/qmz3Cxq8n8I

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 ... https://www.youtube.com/watch?v=9U29pLrCfms