Convert mp3

Convert m4a to mp3

$ sudo apt-get install ffmpeg
$ vi m4a-mp3.sh

#!/bin/sh

for m4a in *.m4a; do
    mp3=`echo "$m4a" | sed -e 's/m4a$/mp3/'`
    if [ ! -e "$mp3" ]; then
        ffmpeg -i "$m4a" -acodec libmp3lame -ab 256k "$mp3"
        test -s "$mp3" && rm "$m4a"
    fi
done

$ chmod +x m4a-mp3.sh
$ ./m4a-mp3.sh

Convert flac to mp3

$ sudo apt-get install ffmpeg
$ vi flac-mp3.sh

#!/bin/bash

for a in ./*.flac; do
  ffmpeg -i "$a" -qscale:a 0 "${a[@]/%flac/mp3}"
done
 
$ chmod +x flac-mp3.sh
$ ./flac-mp3.sh 

Convert legacy ID3 tags 

$ sudo apt-get install python-mutagen
$ mid3iconv -e cp1251 ~/mp3/*