如何在 jupyter 笔记本上将音频数据转换为傅立叶？

Question

我想使用 courier 的转换转换 mp3 文件并导出为 spectrogram.Then 我需要另存为包含我的 mp3 所有频率的 PNG 文件。我怎样才能使用 jupyter notebook 做到这一点？

Answer 1

以下大部分来自：http://myinspirationinformation.com/uncategorized/audio-signals-in-python/

mp3 样本来自 BBC 鸟鸣网站。

我运行在 Jupyter notebook 中使用 Python 3.6 运行 Linux Mint.

from IPython.display import Audio, display
import matplotlib.pyplot as plt
from numpy import fft
import numpy as np
import pydub
from scipy.fftpack import fft
from scipy.io import wavfile
import scipy
import urllib


AUDIO_URL='http://downloads.bbc.co.uk/rmhttp/radio4/science/Birdsong-Blackbird.mp3'
temp_folder = '/home/bill/data/tmp/'


urllib.request.urlretrieve(AUDIO_URL, temp_folder+'file.mp3')
#read mp3 file
mp3 = pydub.AudioSegment.from_mp3(temp_folder+"file.mp3")
#convert to wav
mp3.export(temp_folder+"file.wav", format="wav")
#read wav file
freq, audio_data = scipy.io.wavfile.read(temp_folder+"file.wav")
length = audio_data.shape[0]/freq
channels = audio_data.shape[1]
print('freq: {} length: {} channels: {}'.format(freq, length, channels))
#if stereo grab both channels
channel1 = audio_data[:,0] #left
channel2 = audio_data[:,1] #right

#create a time variable in seconds
time = np.arange(0, float(audio_data.shape[0]), 1) / freq

#plot amplitude (or loudness) over time
plt.figure(1)
plt.subplot(211)
plt.plot(time, channel1, linewidth=0.01, alpha=0.7, color='#ff7f00')
plt.xlabel('Time (s)')
plt.ylabel('Amplitude')
plt.subplot(212)
plt.plot(time, channel2, linewidth=0.01, alpha=0.7, color='#ff7f00')
plt.xlabel('Time (s)')
plt.ylabel('Amplitude')
plt.show()

fourier=fft(channel1)

n = len(channel1)
fourier = fourier[0:int(n/2)]

# scale by the number of points so that the magnitude does not depend on the length
fourier = fourier / float(n)

#calculate the frequency at each point in Hz
freq_array = np.arange(0, (n/2), 1.0) * (freq*1.0/n);

plt.plot(freq_array/1000, 10*np.log10(fourier), color='#ff7f00', linewidth=0.02)
plt.xlabel('frequency in kHz')
plt.ylabel('power in dB')
plt.savefig(temp_folder+'spectrogram.png')

如何在 jupyter 笔记本上将音频数据转换为傅立叶？

how to convert audio data to fourier on jupyter notebook?

audio

jupyter-notebook

fft

spectrogram