captcha_split.py

'''
Quick and dirty way to generate separate wav files depending on the loud voice detected in audio captcha challenge.
Lots of room for improvement.

What is Does:

1. Minor noise removal.
2. Detect louder voices in input wav file
3. Depending on the number of loud voice detected it splits the main wav file.

'''

import wave
import sys
import struct
import os
import time
import httplib
from random import randint


ip = wave.open(sys.argv[1], 'r')
info = ip.getparams()
frame_list = []
for i in range(ip.getnframes()):
    sframe = ip.readframes(1)
    amplitude = struct.unpack('<h', sframe)[0]
    frame_list.append(amplitude)
ip.close()
for i in range(0,len(frame_list)):
    if abs(frame_list[i]) < 25:
        frame_list[i] = 0
################################  Find Out most louder portions of the audio file ###########################
thresh = 30
output = []
nonzerotemp = []
length = len(frame_list)
i = 0
while i < length:
    zeros = []
    while i < length and frame_list[i] == 0:
        i += 1
        zeros.append(0)
    if len(zeros) != 0 and len(zeros) < thresh:
        nonzerotemp += zeros
    elif len(zeros) > thresh:
        if len(nonzerotemp) > 0 and i < length:
            output.append(nonzerotemp)
            nonzerotemp = []
    else:
        nonzerotemp.append(frame_list[i])
        i += 1
if len(nonzerotemp) > 0:
    output.append(nonzerotemp)

chunks = []
for j in range(0,len(output)):
    if len(output[j]) > 3000:
        chunks.append(output[j])
#########################################################################################################

for l in chunks:
    for m in range(0,len(l)):
        if l[m] == 0:
             l[m] = randint(-0,+0)

inc_percent = 1 #10 percent

for l in chunks:
    for m in range(0,len(l)):
        if l[m] <= 0:
            # negative value
            l[m] = 0 - abs(l[m]) + abs(l[m])*inc_percent/100
        else:
            #positive vaule
            l[m] =     abs(l[m]) + abs(l[m])*inc_percent/100

########################################################

# Below code generates separate wav files depending on the number of loud voice detected.

NEW_RATE = 1 #Change it to > 1 if any amplification is required

print '[+] Possibly ',len(chunks),'number of loud voice detected...'
for i in range(0, len(chunks)):
    new_frame_rate = info[0]*NEW_RATE
    print '[+] Creating No. ',str(i),'file..'
    split = wave.open('cut_'+str(i)+'.wav', 'w')
    split.setparams((info[0],info[1],info[2],0,info[4],info[5]))
#   split.setparams((info[0],info[1],new_frame_rate,0,info[4],info[5]))

    #Add some silence at start selecting +15 to -15
    for k in range(0,10000):
        single_frame = struct.pack('<h', randint(-25,+25))
        split.writeframes(single_frame)
    # Add the voice for the first time
    for frames in chunks[i]:
        single_frame = struct.pack('<h', frames)
        split.writeframes(single_frame)

    #Add some silence in between two digits
    for k in range(0,10000):
        single_frame = struct.pack('<h', randint(-25,+25))
        split.writeframes(single_frame)

    # Repeat effect :  Add the voice second time
    for frames in chunks[i]:
        single_frame = struct.pack('<h', frames)
        split.writeframes(single_frame)

    #Add silence at end
    for k in range(0,10000):
        single_frame = struct.pack('<h', randint(-25,+25))
        split.writeframes(single_frame)

    split.close()#Close each files