user/mp3s_to_mkv.sh

   1 #!/bin/bash
   2 # Desc: Converts a directory of mp3s into a single mkv file with chapters
   3 # Usage: mp3s_to_mkv.sh [DIR in] [DIR out] [BITRATE]
   4 # Example: mp3s_to_mkv.sh ./dir_source ./dir_output 48k
   5 # Depends: GNU Coreutils 8.32 (date), ffmpeg, ffprobe
   6 # Ref/Attrib: [1] FFmpeg Formats Documentation https://ffmpeg.org/ffmpeg-formats.html#toc-Metadata-2
   7 # Version: 0.1.0
   8
   9 # plumbing
  10 opus_bitrate="$3"; # e.g. "48k"
  11 script_rundate="$(date +%s)";
  12 dir_tmp="/dev/shm";
  13 dir_in="$(readlink -f "$1")";
  14 dir_out="$(readlink -f "$2")";
  15 file_flist="$dir_tmp"/"$script_rundate"..flist.txt;
  16 file_out_mkv="$dir_out"/output.mkv;
  17 file_albumart="$dir_out"/albumart.png;
  18 file_chapters="$dir_tmp"/"$script_rundate"..chapters.txt;
  19
  20 yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
  21 die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
  22 must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
  23 show_usage() {
  24     # Desc: Display script usage information
  25     # Usage: showUsage
  26     # Version 0.0.2
  27     # Input: none
  28     # Output: stdout
  29     # Depends: GNU-coreutils 8.30 (cat)
  30     cat <<'EOF'
  31     USAGE:
  32         mp3s_to_mkv.sh [DIR in] [DIR out] [BITRATE]
  33
  34     EXAMPLE:
  35       mp3s_to_mkv.sh ./source_dir ./out_dir 48k
  36 EOF
  37 } # Display information on how to use this script.
  38 check_depends() {
  39     if ! command -v ffmpeg; then show_usage; die "FATAL:Missing ffmpeg."; fi;
  40     if ! command -v ffprobe; then show_usage; die "FATAL:Missing ffprobe."; fi;
  41 }; # check dependencies
  42 check_plumbing() {
  43     if [[ $# -ne 3 ]]; then show_usage; die "FATAL:Invalid arg count:$#"; fi;
  44     if [[ ! -d "$dir_in" ]]; then show_usage; die "FATAL:Not a dir:$dir_in"; fi;
  45     if [[ ! -d "$dir_out" ]]; then mkdir -p "$2"; fi;
  46 }; # check arguments
  47 get_media_length() {
  48     # Use ffprobe to get media container length in seconds (float)
  49     # Usage: get_media_length arg1
  50     # Input:  arg1: path to file
  51     # Output: stdout: seconds (float)
  52     # Depends: ffprobe 4.1.8
  53     #          BK-2020-03: die()
  54     local file_in
  55     file_in="$1";
  56     if [[ ! -f $file_in ]]; then
  57         die "ERROR:Not a file:$file_in";
  58     fi;
  59     ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$file_in";
  60 } # Get media container length in seconds via stdout
  61 build_filelist_and_chapters() {
  62     # Depends: var dir_tmp     temporary directory
  63     #          var dir_in      input dir
  64     #          var file_flist  path file list
  65     # Output: file: $file_flist     list of mp3 files for ffmpeg
  66     #         file: $file_chapters  chapters file for ffmpeg
  67
  68     # Change directory to input dir
  69     pushd "$dir_in" || die "FATAL:Directory error:$(pwd)";
  70
  71     local chapter_start=0;
  72     local chapter_end;
  73     local duration;
  74
  75
  76     # Initialize chapter ffmetadata file. See [1].
  77     {
  78         echo ";FFMETADATA1";
  79     } >> "$file_chapters";
  80
  81
  82     find "$dir_in" -type f -iname "*.mp3" | sort | while read -r line; do
  83         local filename="${line#./}";
  84         yell "$(printf "file '%s'\n" "$filename")";
  85         printf "file '%s'\n" "$filename" >> "$file_flist";
  86
  87         # Get duration of the current file
  88         duration=$(get_media_length "$filename");
  89         chapter_end=$(echo "$chapter_start + $duration" | bc -l);
  90
  91         # Write chapter info
  92         {
  93             echo "[CHAPTER]";
  94             echo "TIMEBASE=1/1000";
  95             echo "START=$(echo "scale=0; $chapter_start * 1000" | bc -l)";
  96             echo "END=$(echo "scale=0; $chapter_end * 1000" | bc -l)";
  97             echo "title=$(basename "$filename" .mp3)";
  98         } >> "$file_chapters";
  99
 100         chapter_start=$chapter_end
 101     done
 102
 103     # Return to original dir
 104     popd || die "FATAL:Directory error:$(pwd)";
 105 }; # build file list and chapters for ffmpeg
 106 ffmpeg_convert() {
 107     # Depends: var dir_tmp
 108     #              dir_in
 109     #              dir_out
 110     # Input: file $file_flist     list of mp3 files for ffmpeg
 111     #        file $file_chapters  chapters file for ffmpeg
 112
 113     # Change directory to input dir
 114     pushd "$dir_in" || die "FATAL:Directory error:$(pwd)";
 115
 116     # Concatenate mp3 files into a single WAV file
 117     # Convert WAV to 48 kbps opus mkv file
 118     ffmpeg -nostdin -f concat -safe 0 -i "$file_flist" -c:a pcm_s24le -rf64 auto -f wav - | \
 119         ffmpeg -i - -i "$file_chapters" \
 120                -map_metadata 1 -map_chapters 1 \
 121                -map 0 -c:a libopus -b:a "$opus_bitrate" \
 122                "$file_out_mkv";
 123
 124     # Return to original dir
 125     popd || die "FATAL:Directory error:$(pwd)";
 126 }; # convert mp3s to opus mkv via ffmpeg
 127 save_albumart() {
 128     local file
 129     file="$(find "$dir_in" -type f -iname "*.mp3" | sort | head -n1)";
 130     file="$(readlink -f "$file")";
 131     ffmpeg -nostdin -i "$file" -an -vcodec copy "$file_albumart";
 132 }; # save album art from an mp3 to output dir
 133 main() {
 134     check_depends && yell "DEBUG:check_depends OK";
 135     check_plumbing "$@" && yell "DEBUG:check_plumbing OK";
 136     build_filelist_and_chapters "$@" && yell "DEBUG:build_filelist_and_chapters OK";
 137     ffmpeg_convert "$@" && yell "DEBUG:ffmpeg_convert OK";
 138     save_albumart "$@" && yell "DEBUG:save_albumart OK";
 139 }; # main program
 140
 141 main "$@";