проверьте это:
https://github.com/Ciantic/songdetails
Пример использования:
>>> import songdetails
>>> song = songdetails.scan("data/song.mp3")
>>> print song.duration
0:03:12
Сохранение изменений:
>>> import songdetails
>>> song = songdetails.scan("data/commit.mp3")
>>> song.artist = "Great artist"
>>> song.save()