Autotuner application using GNU Radio

autotune.py

#Test using wav file
import sys
from scipy import *
from pylab import *
from scipy.io import wavfile
import numpy as np


samp_rate, inputa = wavfile.read("test.wav");
size = 2**16;
# size = len(inputa)
outputa =[]
def frequency(sub_array):
	# sub_array = sound_array
	hanning_window = np.hanning(len(sub_array))
	fft = np.fft.fft(hanning_window*sub_array)
	abs_fft = np.abs(fft)
	m = max(abs_fft)
	# print [k for k,j in enumerate(abs_fft) if j==m]
	index = [k for k,j in enumerate(abs_fft) if j==m][0]
	if(index>size/2):index = size-index

	return index*samp_rate/size 

def speedx(sound_array, factor):
    indices = np.round( np.arange(0, len(sound_array), factor) )
    indices = indices[indices < len(sound_array)].astype(int)
    return sound_array[ indices.astype(int) ]

def stretch(sound_array, f, window_size, h):
    phase  = np.zeros(window_size)
    hanning_window = np.hanning(window_size)
    result = np.zeros( len(sound_array) /f)

    for i in np.arange(0, len(sound_array)-(window_size+h), h*f):
        a1 = sound_array[i: i + window_size]
        a2 = sound_array[i + h: i + window_size + h]
        s1 =  np.fft.fft(hanning_window * a1)
        s2 =  np.fft.fft(hanning_window * a2)
        phase = (phase + np.angle(s2/s1)) % 2*np.pi
        a2_rephased = np.fft.ifft(np.abs(s2)*np.exp(1j*phase))
        i2 = int(i/f)
        result[i2 : i2 + window_size] += hanning_window*a2_rephased
    result = ((2**(14)) * result/result.max()) # normalize (16bit)

    return result.astype('int16')

for i in xrange(0, len(inputa),size):
	sub_array = inputa[i:i+size]
	f = frequency(sub_array)
	print f
	n_pitch =12*np.log2(f/440.0)
	n_pitch = np.rint(n_pitch)
	near_frequency = 440.0*np.exp2(n_pitch/12) 
	factor = near_frequency/f
	print near_frequency
	stretched = stretch(inputa[i:i+size], factor, 2**12, 2**10)
	# outputa[i*size:(i+1)*size] = speedx(stretched[2**12:],1/factor)
	nfout = speedx(stretched,1/factor)
	print frequency(nfout),"\n"
	outputa = np.concatenate([outputa,nfout]).astype(int16)

wavfile.write("zest.wav",samp_rate,outputa)