如何从 WAV 文件中提取频率 - python答案

【问题标题】：How can i extract the frequency from WAV file - python如何从 WAV 文件中提取频率 - python
【发布时间】：2020-07-08 16:51:18
【问题描述】：

我正在创建 WAV 文件并编写特定音符频率的列表，该列表由静音音符分开，其持续时间为 44100 sample_rate，例如 440 Hz、静音、351 Hz、静音等。现在我想从 WAV 文件中读取并获取确切的频率列表。我怎样才能做到这一点？谢谢！

这是我对 WAV 代码的注释：

# !/usr/bin/python
# based on : www.daniweb.com/code/snippet263775.html
import math
import wave
import struct
import txtToNote

# Audio will contain a long list of samples (i.e. floating point numbers describing the
# waveform).  If you were working with a very long sound you'd want to stream this to
# disk instead of buffering it all in memory list this.  But most sounds will fit in
# memory.
import wavToNote

audio = []
sample_rate = 44100.0


def append_silence(duration_milliseconds=500):
    """
    Adding silence is easy - we add zeros to the end of our array
    """
    num_samples = duration_milliseconds * (sample_rate / 1000.0)

    for x in range(int(num_samples)):
        audio.append(0.0)

    return


def append_sinewave(freq=440.0, duration_milliseconds=1000, volume=1.0):
    """
    The sine wave generated here is the standard beep.  If you want something
    more aggressive you could try a square or saw tooth waveform.   Though there
    are some rather complicated issues with making high quality square and
    sawtooth waves... which we won't address here :)
    """

    global audio  # using global variables isn't cool.

    num_samples = duration_milliseconds * (sample_rate / 1000.0)

    print("audio:")
    for x in range(int(num_samples)):
        audio.append(volume * math.sin(2 * math.pi * freq * (x / sample_rate)))

    return


def revers_audio():
    print("hi")




def save_wav(file_name):
    # Open up a wav file
    wav_file = wave.open(file_name, "w")

    # wav params
    nchannels = 1

    sampwidth = 2

    # 44100 is the industry standard sample rate - CD quality.  If you need to
    # save on file size you can adjust it downwards. The stanard for low quality
    # is 8000 or 8kHz.
    nframes = len(audio)
    comptype = "NONE"
    compname = "not compressed"
    wav_file.setparams((nchannels, sampwidth, sample_rate, nframes, comptype, compname))

    # WAV files here are using short, 16 bit, signed integers for the
    # sample size.  So we multiply the floating point data we have by 32767, the
    # maximum value for a short integer.  NOTE: It is theortically possible to
    # use the floating point -1.0 to 1.0 data directly in a WAV file but not
    # obvious how to do that using the wave module in python.
    for sample in audio:
        wav_file.writeframes(struct.pack('h', int(sample * 32767.0)))

    wav_file.close()

    return

# txt_to_note is my function that return frequency (float) for each latter in the string
# (the letters are note chords!)
# for simplicity ['a' = 220, 'b' = 467, 'c' = 351, 'd' = 367]
for i in txtToNote.txt_to_note("abcda"):
    append_sinewave(freq=i)
    append_silence()

save_wav("output.wav")

if __name__ == '__main__':
    pass

【问题讨论】：

标签： python wav frequency

【解决方案1】：

您将从文件中读取信号，根据所需的时间分辨率将其窗口化为适当长的块，对每个块运行 FFT 以获取频率数据并找到峰值。

您可以在 Scipy 库中找到窗口化和 FFT。

【讨论】：