Scripts/bin/find-convert-move.sh

#!/usr/bin/env bash
set -euo pipefail # bash strict mode
IFS=$'\n\t'


display_help(){
    echo "This script converts audio files of specified extensions to another specified extension and maintains directory structure."
    echo "Usage: ${0##*/} -p <output-path> -i <input-extensions> -o <output-extension> [music-path/s]"
    echo "Example: ${0##*/} -p /mnt/16gb_pendrive -i flac,wav,ogg -o mp3 ~/Music/Bjork\ Discography ~/Music/MikeOldfield Discography ..."
    echo "Options: "
    echo -e "\t -i -- Input extensions to search for (default: ${input_ext})"
    echo -e "\t -o -- Output extension to convert to (default: ${output_ext})"
    echo -e "\t -p -- Path to store converted files (default: ${output_path})"
    echo -e "\t -f -- Force overwrite existing files"
    echo -e "\t -h -- Display this help message"
    exit 2
}
extract_cover(){
    input_file_path="$1"
    output_file_path="$2"
    # ffmpeg -y -i "$1" -an -vcodec copy "${output_file_path}/cover.jpg"
    find "$input_file_path" -type f -iname "cover*" -exec cp {} "${output_file_path}/" \; || \
        ffmpeg -y -i "$1" -an -vcodec copy "${output_file_path}/cover.jpg"

}
cover_present_in(){
    path="$1"
    find "$path" -type f -iregex "\(folder\|cover\)\.\(png\|jpe?g\)"
}
ffmpeg_convert(){
    input_file="$1"
    output_file="$2"
    echo "Starting conversion..."
    ffmpeg "${force:--n}" -i "$input_file" \
           -vsync 2 -threads 4 \
           "$output_file" &>/dev/null

    if [[ $? -eq 0 ]]; then
        echo "Converted ${input_file} --> ${output_file}"
    else
        echo "Non zero exit code? Remove &/dev/null"
    fi

}
wait_on_max_bg_process(){
    if [[ $(pgrep ffmpeg | wc -w) -ge ${max_processes:-20} ]]; then
        wait $!
    fi
}

# default values
output_path="."
input_ext=".flac\|.wav\|.ogg\|.m4a"
output_ext="opus"
max_processes=10

while getopts ':p:i:o:fDh' opt; do
    case "$opt" in
        p)output_path="${OPTARG%*/}" ;; # making sure to not end with /
        i)input_ext="${OPTARG//,/\\|}" ;; # substitute "," to "\|"  for -regex
        o)output_ext="$OPTARG" ;;
        f)force="-y" ;;
        D)delete_source=1 ;;
        h|\?|:|*) display_help ;;
    esac
done
shift $((OPTIND-1)) # next parameters without flags

# check if nessesary variables are correctly specified
[[ ! -d $output_path || $# -lt 1 ]] && display_help


for input_directory in "$@"; do
    [[ ! -d $input_directory ]] && echo "Not a directory: ${input_directory}" && continue
    mapfile -t input_files < <(find "$input_directory" -mount -type f -regex ".*\(${input_ext}\)$")
    for input_file in "${input_files[@]}"; do
        output_file="${output_path}/${input_file%.*}.${output_ext}"
        output_file_path="${output_file%/*}"
        [[ ! -d $output_file_path ]] && mkdir -p "${output_file_path}"

        input_file_path="${input_file%/*}"
        if [[ $output_file_path != "${old_path:-}" && ! $(cover_present_in "$input_file_path") ]]; then
            extract_cover "$input_file" "$output_file_path"
            old_path="$output_file_path"
        fi

        ffmpeg_convert "$input_file" "$output_file" &
        wait_on_max_bg_process

        [[ ${delete_source:-} -eq 1 ]] && rm "$input_file"
    done
done

wait

echo "FINISHED"