convert m4a to mp3

gistfile1.sh

author=""
title=""
album=""
output="mp3"

for i in `find . -maxdepth 1 -type d 2>/dev/null` 
do
    if [ "$i" = "." ]; then    
        continue
    fi
  album=${i/.\//}
  echo $album
  for filename in $album/*.m4a ; 
  do  
    # echo $filename
    if [ -f "$filename" ] ; then
      if [ ! -d "$output/$album" ] ; then
        mkdir "$output/$album" 
      fi
      basename=`basename "$filename"`
      title=`echo ${basename%.*}`
      file="${title}.mp3"  
      outputfile="$output/$album/$file"
      # echo $outputfile 
      # echo $filename 
      ffmpeg   -y -i "$filename"  -metadata title="$title" -metadata artist="$author" -metadata album="$album" -codec:a libmp3lame  -ab 64k  "${outputfile// /_}"; 
    fi 
  done 
done