Go through files and do something to them. Uses multiprocessing.

batchit.py

import os
import subprocess
from multiprocessing import Pool

def main():
    fileList = []

    for root, dirs, files in os.walk("."):
        for file in files:
            full_file = os.path.abspath("{0}\\{1}".format(root, file))
            if filter_it(filename=full_file):
                fileList.append({'filename':full_file})

    p = Pool(processes=4)
    result = p.map_async(process_it, fileList)
    result.get()
    print "Done"

def filter_it( *args, **kwargs):
    #print kwargs['filename'][-3:]
    if kwargs['filename'][-3:] == "wav":
        return True
    else:
        return False

def process_it( *args, **kwargs):
    print args[0]
    filename = args[0]['filename']
    subprocess.call(["lame", "-h", "-S", filename, filename[:-3] + "mp3"])
    print "Finished with", filename


if __name__ == "__main__":
    main()