m4a2mp3

#!/bin/sh

log()
{
    echo "$(basename $0): $1"
}

IFS='
'

for file in $@; do
    echo "$file"
    if ! expr "$file" : '.*\.m4a' >/dev/null; then
        log "skipping non-m4a file $file"
        continue
    fi

    ffmpeg -i "$file" -ab 256k "${file%m4a}mp3"
    if [ $? -ne 0 ]; then
        log "failed to convert $file"
    fi
done