album-to-video

#!/bin/bash
set -euo pipefail #bash strict mode #mostly this is to preserve vidlist for later inspection if we fail. remember to delete vidlist again yourself!
[ "$#" -lt 3 ] && echo USAGE: "$0 output_file cover_image_file audio_files..." && echo && echo "IMPLEMENTATION:" && cat "$0" && echo && exit 22 #usage message for invalid number of arguments

outfile="$1"
cover="$2"
shift 2
seconds=0
echo >vidlist.txt
echo >vidlist.timestamps.txt

for f in "$@"; do #TODO: may need a `for f in "$a"` loop directly within this to glob correctly?
  if [ -f "$f" ] #the -f (file) check in there is because if the glob is empty it will just return itself as a literal string. You could turn that behavior off using shopt -s nullglob, but this is more posix-y.
  then
    echo "file ${f@Q}" >>vidlist.txt #${f@Q} is an esoteric thing that does escaped substitution. it's like a quoted substitituion. we need in in case the file name has a (single) quote character in it. man, the whole sh model of variables is bad. im past caring. i just accept it now.
    #that's taken care of. Now, for bookkeeping:
    filename=$(basename "$f")
    echo $(date -ud "@$seconds" +%T) ${filename%\.*} >>vidlist.timestamps.txt;
    duration=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$f")
    duration_seconds=${duration%\.*}
    seconds=$((seconds + duration_seconds))
  fi
done

#TODO: Doesn't work with most versions of ffmpeg anymore??
ffmpeg -loop 1 -framerate .2 -i "$cover" -f concat -safe 0 -i vidlist.txt -c copy -shortest "$outfile"
rm vidlist.txt