Python Scipy FFT WAV文件

Question

我有一些WAV文件。我想用SciPy FFT來繪製這些wav文件的頻譜。我會如何去做這件事？

Answer 1

Python提供了幾個API來做到這一點很快。我從this link下載羊咩咩wav文件。您可以將其保存在桌面上，並在終端內保存在cd。在python提示這些線應該足夠：（省略>>>）

import matplotlib.pyplot as plt 
from scipy.fftpack import fft 
from scipy.io import wavfile # get the api 
fs, data = wavfile.read('test.wav') # load the data 
a = data.T[0] # this is a two channel soundtrack, I get the first track 
b=[(ele/2**8.)*2-1 for ele in a] # this is 8-bit track, b is now normalized on [-1,1) 
c = fft(b) # calculate fourier transform (complex numbers list) 
d = len(c)/2 # you only need half of the fft list (real signal symmetry) 
plt.plot(abs(c[:(d-1)]),'r') 
plt.show() 

下面是輸入信號的曲線圖：

這裏是光譜

對於正確輸出，您必須將xlabel轉換爲頻譜圖的頻率。

k = arange(len(data)) 
T = len(data)/fs # where fs is the sampling frequency 
frqLabel = k/T 

如果你要處理一堆文件，就可以實現這個作爲一個功能： 把這些線路中的test2.py：

import matplotlib.pyplot as plt 
from scipy.io import wavfile # get the api 
from scipy.fftpack import fft 
from pylab import * 

def f(filename): 
    fs, data = wavfile.read(filename) # load the data 
    a = data.T[0] # this is a two channel soundtrack, I get the first track 
    b=[(ele/2**8.)*2-1 for ele in a] # this is 8-bit track, b is now normalized on [-1,1) 
    c = fft(b) # create a list of complex number 
    d = len(c)/2 # you only need half of the fft list 
    plt.plot(abs(c[:(d-1)]),'r') 
    savefig(filename+'.png',bbox_inches='tight') 

說，我test.wav和test2.wav在當前工作目錄，在python提示界面下面的命令就足夠了： import test2 map（test2.f，['test.wav'，'test2.wav']）

假設你有100個這樣的文件，你不想單獨輸入他們的名字，你需要glob包：

import glob 
import test2 
files = glob.glob('./*.wav') 
for ele in files: 
    f(ele) 
quit() 

您將需要添加getparams在test2.f如果你的.wav文件不一樣的。