wave file fft

npfft.py

#!/usr/bin/python

import wave
import numpy as np
import math

def dofft(filename, wlen = 16, sz = 44100):
    wlen = wlen * sz / 1000
    print 'wlen:', wlen
    wr = wave.open(filename, 'r')
    dfs = []
    nframes = wr.getnframes()
    freq = np.fft.fftfreq(wlen, d=1.0 / sz)
    da = np.fromstring(wr.readframes(nframes), dtype=np.int16)
    for offset in range(0, nframes, wlen):
        nframes -= wlen
        dfrag = da[offset : offset + wlen]
        df = np.abs(np.fft.fft(dfrag))
        dfs.append(abs(freq[np.argmax(df)]))
    return dfs
    
ms = np.power(2, 1./12)
A = 440.0
q = dofft('dnll16.wav', 10, 44100)
print 'length:', len(q)
ds = []
for hz in q:
    if abs(hz) > ms:
        diff = math.log(hz/A, 2.) * 12
        diff = int(round(diff))
        ds.append(diff)
        
dl = -1000
for d in ds:
    if dl != d:
        print d,
        dl = d