import os
import re
a=re.compile('"[^"]+\.mp3"')
for root, dirs, files in os.walk(".",True):
    for name in files:
        if 'txt' == name.split(".")[-1]:
            f=open(os.path.join(root,name),'r')
            for m in a.findall(f.read()):
                print m

[不是原创。能力有限,有不完美的地方请指正,谢谢。]