var x = index % columns;
var y = index / columns;for f in *.<ext>; do <bash command>; doneffprobe -v error -show_format -show_streams <STREAM_PATH>ffmpeg -loop 1 -i <IMAGE> -i <AUDIO> -c:v libx264 -tune stillimage -c:a aac -b:a 192k -pix_fmt yuv420p -shortest <DESTINATION>