silence_detector.py

import math

class SilenceDetector(object):
    def __init__(self, threshold=20, bits_per_sample=16):
        self.cur_SPL = 0
        self.threshold = threshold
        self.bits_per_sample = bits_per_sample
        self.normal = pow(2.0, bits_per_sample - 1)


    def is_silence(self, chunk):
        self.cur_SPL = self.soundPressureLevel(chunk)
        is_sil = self.cur_SPL < self.threshold
        return is_sil


    def soundPressureLevel(self, chunk):
        value = math.pow(self.localEnergy(chunk), 0.5)
        value = value / len(chunk) + 1e-12
        value = 20.0 * math.log(value, 10)
        return value

    def localEnergy(self, chunk):
        power = 0.0
        for i in range(len(chunk)):
            sample = chunk[i] * self.normal
            power += sample*sample
        return power