Question

我对python很熟悉，但对numpy很熟悉，所以如果我错了，请原谅我。

我正在尝试读取具有多个频率的.wav文件（由静音分隔）。到目前为止，我已经能够读取值并找到文件中存在声音的各个部分。然后，我试图找到离散余弦变换并从中计算出频率（参考：how to extract frequency associated with fft values in python）

但是，我收到了错误：

索引46392超出轴0的大小为25

这是我的代码：

import wave
import struct
import numpy as np

def isSilence(windowPosition):
    sumVal = sum( [ x*x for x in sound[windowPosition:windowPosition+windowSize+1] ] )
    avg = sumVal/(windowSize)
    if avg <= 0.0001:
        return True
    else:
        return False

#read from wav file
sound_file = wave.open('test.wav', 'r')
file_length = sound_file.getnframes()
data = sound_file.readframes(file_length)
sound_file.close()
#data = struct.unpack("<h", data)
data = struct.unpack('{n}h'.format(n=file_length), data)
sound = np.array(data)
#sound is now a list of values

#detect silence and notes
i=0
windowSize = 2205
windowPosition = 0
listOfLists = []
listOfLists.append([])
maxVal = len(sound) - windowSize
while True:
    if windowPosition >= maxVal:
        break
    if not isSilence(windowPosition):
        while not isSilence(windowPosition):
            listOfLists[i].append(sound[windowPosition:windowPosition+ windowSize+1])
            windowPosition += windowSize
        listOfLists.append([]) #empty list
        i += 1
    windowPosition += windowSize

frequencies = []
#Calculating the frequency of each detected note by using DFT
for signal in listOfLists:
    if not signal:
        break
    w = np.fft.fft(signal)
    freqs = np.fft.fftfreq(len(w))
    l = len(signal)

    #imax = index of first peak in w
    imax = np.argmax(np.abs(w))
    fs = freqs[imax]

    freq = imax*fs/l
    frequencies.append(freq)

print frequencies

编辑：这是追溯：

Traceback (most recent call last):
  File "final.py", line 61, in <module>
    fs = freqs[imax]
IndexError: index 46392 is out of bounds for axis 0 with size 21

Answer 1

问题是我假设listOfLists实际上是一个列表列表，但实际上它是一个列表列表。这一行：

        listOfLists[i].append(sound[windowPosition:windowPosition+ windowSize+1])

每次都附加一个列表，但我认为它是将元素附加到现有列表。

例如，如果listOfLists是：

[ [1,2,3] ]

然后，listOfLists [0] .append（[4,5,6]）将给出：

[ [ [1,2,3],[4,5,6] ] ]

但我在期待：

[ [1,2,3,4,5,6] ]

用下面的代码替换有问题的行对我有用：

for v in sound[windowPosition:windowPosition+windowSize+1]:
            listOfLists[i].append(v)

从wav文件python

1 个答案: