Plot Audio dB Level

#!/usr/bin/env python3

# https://stackoverflow.com/questions/13243690/decibel-values-at-specific-points-in-wav-file/13244011#13244011

import scipy.io.wavfile
import numpy as np
import matplotlib.pyplot as plt
import sys, argparse, os, os.path

parser = argparse.ArgumentParser('plot the dB level of a .WAV file')
parser.add_argument('wav_file')
cmdline = parser.parse_args()

samprate, wavdata = scipy.io.wavfile.read(cmdline.wav_file)
numchunks = len(wavdata)/10
chunks = np.array_split(wavdata.astype(np.int64), numchunks)

ref_level = (1 << 15)-1 # 16-bit (signed) PCM
dbs = [20*np.log10( max(np.sqrt(np.mean(chunk**2)),.0001) / ref_level ) for chunk in chunks]

total_time_sec = len(wavdata) / samprate
t = np.linspace(0,total_time_sec,len(wavdata)/10)
plt.plot(t,dbs,'k-')
plt.title(os.path.basename(cmdline.wav_file))
plt.grid(True)
plt.show()