1. install VLC 3. create a file called convert.sh on your desktop ie. ~/Desktop/convert.sh 4. chmod +x convert.sh 5. make the contents of convert.sh #!/bin/sh vlc="/Applications/VLC.app/Contents/MacOS/VLC" ext="mp3" dst="/Users/[your name]/Desktop/" for a in *$fmt; do $vlc -I dummy -vvv "./$a" --sout "#transcode{acodec=mp3,ab=128,channels=2,samplerate=44100}:std{mux=raw,dst=\"$dst$a.$ext\",access=file}" vlc://quit done 6. open terminal and cd to folder that has your AAC music files ie. ~/Desktop/AAC 7. then type ~/Desktop/convert.sh *.aac 8. sit back and relax as the files are converted Notes http://wiki.videolan.org/How_to_Batch_Encode http://wiki.videolan.org/Documentation:Streaming_HowTo_New#Example_commandline:_Converting_an_audio_file_to_a_MP3_file