dmastropole

# Extract the first second of audio
import essentia
import essentia.standard

loader = essentia.standard.MonoLoader(filename='example.wav', sampleRate=44100)
audio = loader()
sec_audio = audio[0:44100]

dmastropole

# Plot the first second of audio
import matplotlib
import matplotlib.pyplot as plt
import seaborn as sns

plt.plot(sec_audio)
plt.title('Sound Wave')
plt.xlabel('Samples')
plt.ylabel('Amplitude')

dmastropole

import numpy as np

window = np.hanning(25)
plt.plot(window)
plt.title('Hanning Window')
plt.xlabel('Time (ms)')

dmastropole

# Define function for computing mels
def mel_formula(f):
    return 2595 * np.log(1 + f/700)
    
# Frequency range
f_low = 40
f_high = 44100 / 2  # Nyquist frequency
f = np.linspace(f_low, f_high)

# Plot relationship between frequency and mels

dmastropole

def inverse_mel_formula(m):
    return 700 * (np.power(10, m/2595) - 1)

# Convert back to frequency
f = inverse_mel_formula(m)
print(f)

dmastropole

for n in range(n_bands):
    plt.plot(f[n:n+3], [0, 1, 0])  # Does the "+ 2" make sense now?

plt.title('Mel Filterbanks')
plt.xlabel('Frequency (Hz)')

dmastropole

from essentia.standard import MFCC, FrameGenerator

mfcc = MFCC(highFrequencyBound=f_high,
            lowFrequencyBound=f_low,
            inputSize=1024,
            numberBands=n_bands,
            numberCoefficients=13,
            type='magnitude',
            sampleRate=44100)

dmastropole

from essentia.standard import UnaryOperator

# Convert to decibels
log10 = UnaryOperator(type='log10')
log_mels = log10(mels)

# Plot the mel band powers
plt.bar(np.arange(len(log_mels)), log_mels, align='center')
plt.title('Log of the Mel Band Powers')
plt.xlabel('Mel Bands')

dmastropole

from essentia.standard import MelBands

# Compute the mel band powers
melbands = MelBands(lowFrequencyBound=f_low,
                    highFrequencyBound=f_high,
                    inputSize=1024,
                    numberBands=n_bands,
                    type='magnitude',  # We already computed the power.
                    sampleRate=44100)
mels = melbands(spec)

dmastropole

from essentia.standard import Windowing, PowerSpectrum

# Compute the spectrum of a frame
w = Windowing(type='hann')
spectrum = PowerSpectrum(size=1024)
frame = audio[0:1024]
spec = spectrum(w(frame))

# Plot the spectrum of a frame
plt.plot(spec)