Python Scipy FFT wav 文件 [英] Python Scipy FFT wav files

问题描述

我有一些 wav 文件.我想使用 SciPy FFT 来绘制这些 wav 文件的频谱.我该怎么做?

I have a handful of wav files. I'd like to use SciPy FFT to plot the frequency spectrum of these wav files. How would I go about doing this?

推荐答案

Python 提供了几个 api 来相当快地做到这一点.我从 这个链接 下载了羊叫声 wav 文件.您可以将它保存在桌面上，然后在终端内 cd 那里.python 提示中的这些行应该足够了:(省略 >>>>)

Python provides several api to do this fairly quickly. I download the sheep-bleats wav file from this link. You can save it on the desktop and cd there within terminal. These lines in the python prompt should be enough: (omit >>>)

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()

这是输入信号的绘图:

Here is a plot for the input signal:

这是光谱

为了获得正确的输出，您必须将 xlabel 转换为频谱图的频率.

For the correct output, you will have to convert the xlabelto the frequency for the spectrum plot.

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

如果你必须处理一堆文件，你可以把它作为一个函数来实现:将这些行放在 test2.py 中:

If you are have to deal with a bunch of files, you can implement this as a function: put these lines in the 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')

说，我当前工作目录下有test.wav和test2.wav，python提示界面下面的命令就够了:导入测试2地图(test2.f, ['test.wav','test2.wav'])

Say, I have test.wav and test2.wav in the current working dir, the following command in python prompt interface is sufficient: import test2 map(test2.f, ['test.wav','test2.wav'])

假设你有 100 个这样的文件并且你不想单独输入它们的名字，你需要 glob 包:

Assuming you have 100 such files and you do not want to type their names individually, you need the glob package:

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

如果您的 .wav 文件不是同一位，您将需要在 test2.f 中添加 getparams.

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