#!/usr/bin/env python

import wave, sys

if (len(sys.argv) != 3):
    print sys.argv[0], "<archivo.wav> <salida.wav>"
    exit(1)

wi = wave.open(sys.argv[1], "rb")

if (wi.getnchannels() != 2): # Si no es stereo
    print "El script solo funciona con sonido Stereo"
    exit(2)

wo = wave.open(sys.argv[2], "wb")
wo.setnchannels(2)
wo.setsampwidth(wi.getsampwidth())
wo.setframerate(wi.getframerate())

l = len(wi.readframes(1))
hl = l / 2
wi.rewind()

while True:
    c = wi.readframes(1)
    if (len(c) < 1):
        break
    s = c[ hl : ] + c[ : hl]
    wo.writeframes(s)

wi.close()
wo.close()