1 | #! /usr/bin/env python |
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2 | |
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3 | """Create a filterbank from a list of frequencies. |
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4 | |
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5 | This demo uses `aubio.filterbank.set_triangle_bands` to build a set of |
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6 | triangular filters from a list of frequencies. |
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7 | |
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8 | The filterbank coefficients are then modified before being displayed.""" |
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9 | |
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10 | import aubio |
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11 | import numpy as np |
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12 | import matplotlib.pyplot as plt |
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13 | |
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14 | # sampling rate and size of the fft |
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15 | samplerate = 48000 |
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16 | win_s = 2048 |
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17 | |
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18 | # define a list of custom frequency |
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19 | freq_list = [60, 80, 200, 400, 800, 1600, 3200, 6400, 12800, 24000] |
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20 | # number of filters to create |
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21 | n_filters = len(freq_list) - 2 |
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22 | |
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23 | # create a new filterbank |
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24 | f = aubio.filterbank(n_filters, win_s) |
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25 | freqs = aubio.fvec(freq_list) |
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26 | f.set_triangle_bands(freqs, samplerate) |
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27 | |
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28 | # get the coefficients from the filterbank |
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29 | coeffs = f.get_coeffs() |
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30 | # apply a gain to fifth band |
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31 | coeffs[4] *= 6. |
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32 | # load the modified coeffs into the filterbank |
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33 | f.set_coeffs(coeffs) |
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34 | |
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35 | # display the band gains in a loglog plot |
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36 | freqs = np.vstack([np.arange(win_s // 2 + 1) * samplerate / win_s] * n_filters) |
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37 | plt.title('filterbank built from a list of frequencies\n' |
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38 | 'The 5th band has been amplified by a factor 6.') |
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39 | plt.loglog(freqs.T, f.get_coeffs().T, '.-') |
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40 | plt.xlim([50, samplerate/2]) |
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41 | plt.ylim([1.0e-6, 2.0e-2]) |
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42 | plt.xlabel('log frequency (Hz)') |
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43 | plt.ylabel('log amplitude') |
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44 | plt.show() |
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