DevOps-Bash-tools/mp3_set_track_order.sh

#!/usr/bin/env bash
#  vim:ts=4:sts=4:sw=4:et
#
#  Author: Hari Sekhon
#  Date: 2020-07-21 11:36:49 +0100 (Tue, 21 Jul 2020)
#
#  https://github.com/harisekhon/bash-tools
#
#  License: see accompanying Hari Sekhon LICENSE file
#
#  If you're using my code you're welcome to connect with me on LinkedIn and optionally send me feedback to help steer this or other code I publish
#
#  https://www.linkedin.com/in/harisekhon
#

set -euo pipefail
[ -n "${DEBUG:-}" ] && set -x
srcdir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

# shellcheck disable=SC2034
usage_description="
Adds / Modifies track number metadata across all MP3 files in the given directories to restructure audiobooks to be contiguous for Mac's Books.app

If no directory arguments are given, works on MP3s under \$PWD. Finds MP3 files within 1 level of subdirectories

Shows the list of MP3 files with the proposed track number metadata and prompts for confirmation before proceeding for safety

MP3 filenames should be in lexical order before running this
"

# used by usage() in lib/utils.sh
# shellcheck disable=SC2034
usage_args="[<dir1> <dir2> ...]"

# shellcheck disable=SC1090
. "$srcdir/lib/utils.sh"

help_usage "$@"

check_bin id3v2

# used to pipe file list inline which is more comp sci 101 correct but that could create a race condition on second
# evaluation of file list changing after confirmation prompt, and RAM is cheap, so better to use a static list of files
# stored in ram and operate on that since it'll never be that huge anyway

mp3_files="$(for dir in "${@:-$PWD}"; do find "$dir" -maxdepth 2 -iname '*.mp3' || exit 1; done)"

if is_blank "$mp3_files"; then
    echo "No MP3 files found"
    exit 1
fi

echo "List of MP3 files and their metadata track ordering:"

echo

{
    i=0;
    while read -r mp3; do
        [ -n "$mp3" ] || continue
        ((i+=1))
        printf '%s\t%s\n' "$i" "$mp3"
    done
} <<< "$mp3_files"

echo

read -r -p 'Are you happy with this track metadata ordering? (y/N) ' answer

if [ "$answer" != "y" ]; then
    echo "Aborting..."
    exit 1
fi

echo

{
    i=0;
    while read -r mp3; do
        [ -n "$mp3" ] || continue
        ((i+=1))
        echo "setting track order $i on '$mp3'"
        id3v2 --track "$i" "$mp3"
    done
} <<< "$mp3_files"