#!/bin/bash
for line in *WMA
do
  M4A=`echo ${line%%.*}.m4a | sed -e 'y/\
ABCDEFGHIJKLMNOPQRSTUVWXYZ\
abcdefghijklmnopqrstuvwxyz\
0123456789()− /\
ABCDEFGHIJKLMNOPQRSTUVWXYZ\
abcdefghijklmnopqrstuvwxyz\
0123456789()__/'`
  ffmpeg -y -i "${line}" -threads 8 "${M4A}"
  mv "${line}" bkup
done