http://tuxtweaks.com/2008/08/how-to-resample-mp3-audio-files-on-linux-using-lame/

cptag.sh

#!/bin/bash
#
#cptag - A script to resample mp3 files with LAME and
#        copy id3v2 tags from the old file to the new one.
#
#####################

# Read id3 tags and write to file
mid3v2 -l "$1" > tag2.txt

# Resample music file

lame -V5 --vbr-new --resample 44.1 "$1" "resample/$1"

# Set value of variable 'title'
if
   grep TIT2= tag2.txt > /dev/null  #Test if title tag exists
then
   title=`grep TIT2= tag2.txt | sed "s:TIT2=::"`
   echo $title
else
   echo "Title tag does not exist."
fi

# Set value of variable 'album'
if
   grep TALB= tag2.txt > /dev/null  #Test if album tag exists
then
   album=`grep TALB= tag2.txt | sed "s:TALB=::"`
   echo $album
else
   echo "Album tag does not exist."
fi

# Set value of variable 'artist'
if
   grep TPE1= tag2.txt > /dev/null  #Test if artist tag exists
then
   artist=`grep TPE1= tag2.txt | sed "s:TPE1=::"`
   echo $artist
else
   echo "Artist tag does not exist."
fi

# Set value of variable 'track'
if
   grep TRCK= tag2.txt > /dev/null  # Test if track tag exists
then
   track=`grep TRCK= tag2.txt | sed "s:TRCK=::"`
   echo $track
else
   echo "Track tag does not exist."
fi

# Set value of variable 'genre'
if
   grep TCON= tag2.txt > /dev/null  # Test if genre tag exists
then
   genre=`grep TCON= tag2.txt | sed "s:TCON=::"`
   echo $genre
else
   echo "Genre tag does not exist."
fi

# Write tags to file
mid3v2 -t "$title" -A "$album" -a "$artist" -T "$track" -g "$genre" "resample/$1"

exit

mp3shrink.sh

#!/bin/bash
#
#mp3shrink - A script to resample all mp3 files in a
# directory.  This script calls the cptag script which
# must also be in the user's path. cptag depends upon
# lame and mid3v2 (mid3v2 can be found in the
# python-mutagen package).
#
# It is suggested that both the mp3shink and cptag
# scripts be placed in the user's private bin (~/bin).
######################################################

# List mp3's in current directory.
ls *.mp3 > mp3_list
ls *.MP3 >> mp3_list

# Parse the mp3_list and replace spaces with escaped spaces.
sed -i 's: :\\ :g' mp3_list

# Check if resample directory exists and create it if it doesn't.
if
   test -e ./resample
then
   echo "resample directory/file already exists - delete it? (Y/n)"
   read reply
   if
     [ "$reply" != "n" ]
   then
     rm -r resample
     mkdir resample
   else
     exit
   fi
else
   mkdir resample
fi

# Resample each mp3 and write tags using the cptag script
cat mp3_list |while read song
do
   echo "$song"
   cptag "$song"
done

#clean up
if
   test -e mp3_list
then
   rm mp3_list
fi
if
   test -e tag2.txt
then
   rm tag2.txt
fi
exit