python `wave`: AttributeError: 'NoneType' object has no attribute 'write' in Python

Question

I'm having a trouble running the following code:

import numpy as np
import wave
import struct

amplitude = 30000
frequency = 100
duration = 3
fs = 44100
num_samples = duration * fs

num_channels = 1
sampwidth = 2
num_frames = num_samples
comptype = "NONE"
compname = "not compressed"

t = np.linspace(0, duration, num_samples, endpoint = False)
x = amplitude * np.cos(2*np.pi * frequency * t )

wav_file = wave.open("One_Life.wav",'w')
wav_file.setparams((num_channels, sampwidth,fs,num_frames,comptype,compname))
for s in x:
  wav_file.writeframes(struct.pack('h',int(s)))

  wav_file.close()

The error I'm getting is as follow:

AttributeError: 'NoneType' object has no attribute 'write'

I'm unable to figure this one out, can you please help me?

Guy · Accepted Answer · 2020-01-01 11:20:13Z

2

Move wav_file.close() out of the loop

for s in x:
    wav_file.writeframes(struct.pack('h',int(s)))

wav_file.close()

writeframes() has _file.write internally, but you are closing the file, setting it to None. From wave.py

def writeframes(self, data):
    self.writeframesraw(data)
    #...

def writeframesraw(self, data):
    #...
    self._file.write(data)
    #...

def close(self):
    self._file = None
    #...

answered Jan 1, 2020 at 11:20

Guy

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6 Comments

Sheng Over a year ago

what do you mean ?

Guy Over a year ago

@Sheng What are you referring to?

Guy Over a year ago

@Sheng This is the source code, I added the relevant code to the question to show the process. You are using writeframes() which call writeframesraw() which use the variable self._file. When you call close() self._file is set to None.

Sheng Over a year ago

So I need to find wave.py?

Guy Over a year ago

@Sheng No, all you need to do is move wav_file.close() outside the loop. See the first code block in my answer.

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