boot.lv 0xDEAD BEEF Konkurss 4

def k4():
    # beginning sequnce of nothing_special.wav: nothing, special, nothing, nothing, ...

    f = open('nothing_special.wav', 'rb')
    data = f.read()[44:]  # skip wav header
    f.close()

    ns_len = data[64:].index(data[:64]) + 64
    n_len = data[ns_len+1:].index(data[:64])+1
    s_len = ns_len-n_len
    nothing = data[:n_len]
    special = data[n_len:ns_len]

    bit = 0
    b = 0
    i = 0
    b_array = bytearray()
    while i < len(data):
        bit += 1
        b <<= 1
        if data[i:i+len(nothing)] == nothing:
            i += len(nothing)
        else:
            i += len(special)
            b += 1
        if bit == 8:
            b_array.append(b)
            b = bit = 0
    f = open('atbilde.bmp', 'wb')
    f.write(b_array)
    f.close()

k4()