Convert multiple MP4 to MP3

#!/bin/bash

IFS='
'
if  ! [ -d "mp3f" ]
then
   mkdir mp3f
fi
for i in `ls *.MP4`
do
   echo
    base=$(basename "${i}" .mp4)

    mplayer -vc null -vo null -nocorrect-pts -ao pcm:waveheader "${i}"
    RV=$?
    if [[ $RV != 0 ]] ; then
        echo "mplayer completed unsuccessfully -- exiting."
        exit
    fi

    # Convert .wav to .mp3
    lame -h -b 192 audiodump.wav "${base}.mp3" ${VERB}
    RV=$?
    if [[ $RV != 0 ]] ; then
        echo "lame completed unsuccessfully -- exiting."
        exit
    fi
done

IFS=' '

# Cleanup Temporary File
rm audiodump.wav

echo "Conversion complete."