python - numpy 数组的谱质心

Question

我有一个 .wav 文件(在本例中称为“piano2.wav”)。

我想在Python中找到光谱质心。

使用这里另一篇文章中的代码我有这个功能:

import numpy as np
from scipy.io.wavfile import read

def spectral_centroid(x, samplerate=44100):
    magnitudes = np.abs(np.fft.rfft(x))
    length = len(x)
    freqs = np.abs(np.fft.fftfreq(length, 1.0/samplerate)[:length//2+1])
    return np.sum(magnitudes*freqs) / np.sum(magnitudes) 

我使用 scipy.io.wavfile.read 将 wav 文件读取到 numpy 数组中，然后尝试将其输入到上面的函数中

a=read("piano2.wav")
print("Spectral centroid is " + spectral_centroid(a[1]))

这是我收到的错误

  File "test.py", line 20, in <module>
    print("Spectral centroid is " + spectral_centroid(a[1]))
  File "test.py", line 8, in spectral_centroid
    return np.sum(magnitudes*freqs) / np.sum(magnitudes) 
ValueError: operands could not be broadcast together with shapes (302712,2) (151357,)

Answer 1

您正在尝试将不同形状的数组(幅度和频率)相乘:

a = np.arange(10)
b = np.arange(5)
print(a*b)

ValueError: operands could not be broadcast together with shapes (10,) (5,)

这可能有帮助:

def spectral_centroid(x, samplerate=44100):
    magnitudes = np.abs(np.fft.rfft(x))
    length = len(x)
    freqs = np.abs(np.fft.fftfreq(length, 1.0/samplerate)[:length//2+1])
    magnitudes = magnitudes[:length//2+1]
    return np.sum(magnitudes*freqs) / np.sum(magnitudes)