audio-reactive-led-strip/python/dsp.py

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from __future__ import print_function
import numpy as np
import config
import melbank
class ExpFilter:
"""Simple exponential smoothing filter"""
def __init__(self, val=0.0, alpha_decay=0.5, alpha_rise=0.5):
"""Small rise / decay factors = more smoothing"""
assert 0.0 < alpha_decay < 1.0, 'Invalid decay smoothing factor'
assert 0.0 < alpha_rise < 1.0, 'Invalid rise smoothing factor'
self.alpha_decay = alpha_decay
self.alpha_rise = alpha_rise
self.value = val
def update(self, value):
if isinstance(self.value, (list, np.ndarray, tuple)):
alpha = value - self.value
alpha[alpha > 0.0] = self.alpha_rise
alpha[alpha <= 0.0] = self.alpha_decay
else:
alpha = self.alpha_rise if value > self.value else self.alpha_decay
self.value = alpha * value + (1.0 - alpha) * self.value
return self.value
def rfft(data, window=None):
window = 1.0 if window is None else window(len(data))
ys = np.abs(np.fft.rfft(data * window))
xs = np.fft.rfftfreq(len(data), 1.0 / config.MIC_RATE)
return xs, ys
def fft(data, window=None):
window = 1.0 if window is None else window(len(data))
ys = np.fft.fft(data * window)
xs = np.fft.fftfreq(len(data), 1.0 / config.MIC_RATE)
return xs, ys
def create_mel_bank():
global samples, mel_y, mel_x
samples = int(config.MIC_RATE * config.N_ROLLING_HISTORY / (2.0 * config.FPS))
mel_y, (_, mel_x) = melbank.compute_melmat(num_mel_bands=config.N_FFT_BINS,
freq_min=config.MIN_FREQUENCY,
freq_max=config.MAX_FREQUENCY,
num_fft_bands=samples,
sample_rate=config.MIC_RATE)
samples = None
mel_y = None
mel_x = None
create_mel_bank()