FLAC-to-MP3 Mass Converter

flac2mp3

#! /bin/bash
#
# flac2mp3 — Convert FLAC files to MP3.
#
# Author: Micah Elliott <mde MicahElliott com>
# Date:   Feb 2008 (not sure if any util has obviated this)
#
# Many people store their music collections in FLAC format these days
# since it’s nice to have lossless compressed copies, and disks are
# cheap.  But people also need to convert their FLAC collections into
# MP3 whenever they load music onto their MP3 players (for
# FLAC-unequipped players or any time you want to maximize your
# space).  So this tool is needed for generation of (typically)
# temporary MP3 files.
#
# I wanted to use soundconverter to perform conversion operations, but
# it is lacking the abililty to retain the tag information.
#
# Ideas from thread
# (http://www.linuxtutorialblog.com/post/solution-converting-flac-to-mp3)
# and soundconverter (http://soundconverter.berlios.de/)
#
# Features to consider:
#   * Detection of already-existing output files
#   * Resume from interrupted conversion
#   * Envar to locate the mp3 storage area
#   * Maintain dir structure of source
#   * Creation of a link-farm
#   * Timing of each file conversion
#   * Spinner/percentage indicator
#   * Speed up the conversion process
#   * Multiple output formats (mp3 or ogg)
#   * Some sort of interactive selection facility
#
# Options:
#   -w overWrite  (default to skip existing .mp3)
#   -o Outdir
#   -b Base-depth[=0]


usage() {
    echo "ERROR: $1" 1>&2
    echo
    exit 1
}

msg() {
    test -n "$quiet" ||
        echo "$1"
}

prog=$(basename $0)
version="0.1"
usagetxt="\
usage: $prog [OPTS] DIR …
   or: $prog [OPTS] FILE …

Convert FLAC files to MP3.

  -o DIR    Output DIR to hold MP3s
  -w        overWrite any pre-existing files
  -b        Base depth
  -q        try to be Quiet
  -h        print this Help message
  -v        print Version

Report bugs to <mde@micahelliott.com>"

# Parse optional behavior
outdir="./mp3"
overwrite=
while getopts ":hwo:b:qv" opt; do
    case $opt in
        w ) overwrite=1;;
        o ) outdir="$OPTARG" ;;
        b ) basedepth=1 ;;
        q ) quiet=1 ;;
        h ) echo "$usagetxt"; exit 0; ;;
        v ) echo "$version"; exit 0; ;;
        \? ) usage "Illegal option — $OPTARG";;
    esac
done
shift $(($OPTIND - 1))

test ! -d $outdir && {
    mkdir -p $outdir ||
        usage "Cannot create output dir $output."
}

requirements="flac metaflac id3v2 lame"
for r in $requirements ; do
    which $r &>/dev/null ||
        usage "This script requires: $requirements"
done

# Modify the lame options to your preference
lameopts=" --vbr-new -B 256 "

infiles="" indirs=""
for a in $@ ; do
    test -f $a && infiles="$infiles $a"
    test -d $a && indirs="$indirs $a"
done
test -n "$infiles" -a -n "$indirs" &&
    usage "Can’t specify dirs AND files."

test -n "$indirs" &&
    flacfiles="$(find -L $indirs -type f -name '*.flac')" ||
    flacfiles="$infiles"

test -z "$flacfiles" &&
    usage "Did not find any .flac files."

tomp3() {
    unset ARTIST ALBUM TITLE COMMENT GENRE DATE TRACKNUMBER

    # Use metaflac to extract tags, then use sed to add double-quoting
    # to field values to make them usable as bash vars.
    eval $(metaflac --export-tags-to=- "$flacfile" | sed 's/=\(.*\)/="\1"/')

    msg "Converting to MP3 format: $flacfile"
    flac --silent -c -d "$flacfile" | lame --quiet $lameopts - $outdir/"$mp3file"

    id3v2 \
        -a "$ARTIST" \
        -A "$ALBUM" \
        -t "$TITLE" \
        -c "$COMMENT" \
        -g "$GENRE" \
        -y "$DATE" \
        -T "$TRACKNUMBER" \
        "$outdir/$mp3file"
}

for flacfile in $flacfiles ; do
    # Convert the filename suffix.
    mp3file=$(basename "${flacfile%.flac}.mp3")
    if [ ! -f "$outdir/$mp3file" ] ; then
        tomp3 "$flacfile"
    elif [ -z "$overwrite" ]; then
        tomp3 "$flacfile"
    else
        echo  "Skipping already existing $mp3file" ||
        tomp3 "$flacfile"
    fi
done