Audio power from a WAV file

stille.py

from dataclasses import dataclass

import librosa
import numpy as np
import matplotlib.pyplot as plt

@dataclass
class Audio:
    samples: np.ndarray
    rate: int


def read_wav(filename):
    """Read a wav file into a numpy array.

    Args:
        filename (str): Path to the wav file.

    Returns:
        A numpy array with floating point values between -1 and 1.
    """
    samples, rate = librosa.load(filename, sr=None)
    return Audio(samples, rate)


def rms(samples, window_size):
    """Compute the root mean square of a signal with a moving window.
    
    RMS is closely related to audio power.
    """
    squared = np.power(samples, 2)
    kernel = np.ones(window_size) / float(window_size)
    convolved = np.convolve(squared, kernel, mode="same")
    return np.sqrt(convolved)


if __name__ == "__main__":
    audio = read_wav("data/clip-05.wav")
    truncate_seconds = 20  # First twenty seconds
    rms = rms(audio.samples[:audio.rate * truncate_seconds], int(0.3 * audio.rate) )  # 300 ms window
    t = np.linspace(0, len(rms) / audio.rate, num=len(rms))
    plt.figure(1)
    plt.title("Signal Power...")
    plt.plot(t, rms)
    plt.show()