#!/usr/bin/env python

# overwrites the samplerate in a WAV file with a new value

import sys
from struct import *


def replace_samplerate(fname, samprate):
    n = open(fname, 'r+')
    head = n.read(44)

    e = unpack('<22shiihh8s', head)
    f = []
    f.extend(e)
    
    f[2] = samprate
    # ByteRate = SampleRate * NumChannels * BitsPerSample/8

    f[3] = f[2] * f[1] * f[5]/8
    head2 = pack('<22shiihh8s', f[0],f[1],f[2],f[3],f[4],f[5],f[6])

    n.seek(0)
    n.write(head2)
    n.close()


if len(sys.argv) > 1:
    # first arg is new samplerate
    newrate = int(sys.argv[1])

    # remaining args are filenames
    for fname in sys.argv[2:]:
        try:
            replace_samplerate(fname, newrate)
            print 'converted %s to %d' % (fname, newrate)
        except Exception,ex:
            print "Error converting %s: %s" % (fname, str(ex))