How to normalize the loudness of an entire music library?

Question

I have a ~15 GB music collection comprised of MP3, FLAC and M4A files.
Is there a program that could run through an entire directory tree and normalize the loudness of all the audio files it finds to the same level?
ReplayGain is perfect for this, as I understand it, but I'm still not sure how to go about accomplishing this task. :newbie:
Thanks!

Answer 1

mp3gain sucks majorly... use this script instead of calling mp3gain directly:
it makes sure that replaygain is PROPERLY added into the id3v2 field instead of a) modifying the actual audio data or b) using the crappy apev2 tags.
Script needs eyed3 from aur.
#!/bin/sh
LC_NUMERIC=POSIX; export LC_NUMERIC
MP3GAIN=`which mp3gain`
if [[ $? != 0 ]]; then
echo "mp3gain executable not found." >&2
exit 1
fi
EYED3=`which eyeD3`
if [[ $? != 0 ]]; then
echo "eyeD3 executable not found." >&2
exit 1
fi
if [[ $# > 1 || $# == 1 && $1 != "-f" ]] ; then
echo "Usage: `basename $0` [-f]" >&2
echo " for ReplayGain'ing all mp3 file into current directory" >&2
echo " -f -- force re-ReplayGain'ing for already ReplayGain'ed files" >&2
exit 2
fi
if [[ $# == 0 ]]; then
$EYED3 --no-color *.mp3 \
| egrep -i '^UserTextFrame: \[Description: replaygain_album_gain\]$' >/dev/null 2>&1
if [[ $? == 0 ]]; then
echo "Files already ReplayGain'ed." >&2
exit 1
fi
fi
$MP3GAIN *.mp3
TMPFILE=`mktemp`
for n in *.mp3; do
$MP3GAIN -s c "$n" > $TMPFILE
$MP3GAIN -s d "$n"
TRACK_GAIN=`awk '/^Recommended "Track" dB / { printf("%+.2f dB", $5) }' $TMPFILE`
ALBUM_GAIN=`awk '/^Recommended "Album" dB / { printf("%+.2f dB", $5) }' $TMPFILE`
TRACK_PEAK=`awk '/^Max PCM / { printf("%.6f", $7/32768) }' $TMPFILE`
ALBUM_PEAK=`awk '/^Max Album PCM / { printf("%.6f", $8/32768) }' $TMPFILE`
$EYED3 \
--set-user-text-frame="replaygain_track_gain:$TRACK_GAIN" \
--set-user-text-frame="replaygain_track_peak:$TRACK_PEAK" \
--set-user-text-frame="replaygain_album_gain:$ALBUM_GAIN" \
--set-user-text-frame="replaygain_album_peak:$ALBUM_PEAK" \
"$n"
done
rm -f $TMPFILE
using this method the actual audio file is NOT changed at all, you can safely use this method on your original files. all this does is creating a few tags.
for ogg you can use vorbisgain and for flac use metaflac.
The easiest way to do it would be wine+foobar2000 -> load all your files in a huge playlist -> rightclick -> replaygain -> album gain by tag.
Last edited by Rasi (2011-09-02 15:14:17)