Convert a folder of aax audiobooks into m4b files

aax_convert.sh

#!/bin/bash
trap 'exit 130' INT

# Fill in default activation bytes value to save using the argument every time
# Reference: https://audible-tools.github.io/

ACTIVATION_BYTES="" 

usage() {
  echo "Usage: $(basename "$0") [-a activation_bytes]"
  echo ""
  echo "Converts all .aax files in the current directory to .m4b,"
  echo "and saves them in a subfolder called ./conv."
  echo "Output files are renamed and organised in subfolders: /artist/album/artist-title.m4b"
  echo ""
  echo "Options:"
  echo "  -a  Audible activation bytes (default: $ACTIVATION_BYTES)"
  echo "  -h  Show this help message"
}

for arg in "$@"; do [[ "$arg" == "--help" ]] && usage && exit 0; done
while getopts "a:h" opt; do
  case $opt in
    a) ACTIVATION_BYTES="$OPTARG" ;;
    h) usage; exit 0 ;;
  esac
done

mkdir -p conv
for i in *.aax; do
  author=$(ffprobe -activation_bytes "$ACTIVATION_BYTES" -v quiet -show_entries format_tags=artist \
    -of default=noprint_wrappers=1:nokey=1 "$i" \
    | tr -d '/:*?"<>|\\' | sed 's/  */ /g;s/^ //;s/ $//')
  album=$(ffprobe -activation_bytes "$ACTIVATION_BYTES" -v quiet -show_entries format_tags=album \
    -of default=noprint_wrappers=1:nokey=1 "$i" \
    | tr -d '/:*?"<>|\\' | sed 's/  */ /g;s/^ //;s/ $//')
  title=$(ffprobe -activation_bytes "$ACTIVATION_BYTES" -v quiet -show_entries format_tags=title \
    -of default=noprint_wrappers=1:nokey=1 "$i" \
    | tr -d '/:*?"<>|\\' | sed 's/  */ /g;s/^ //;s/ $//')

  outdir="conv/${author}/${album}"
  mkdir -p "$outdir"

  echo "${author} - ${title}"
  ffmpeg -activation_bytes "$ACTIVATION_BYTES" -i "$i" \
    -map 0:a -map 0:v -codec copy -disposition:v attached_pic \
    "${outdir}/${author}-${title}.m4b"
done