[41121f5] | 1 | #! /usr/bin/env python |
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[735a739] | 2 | |
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[eff63ab] | 3 | """Create a filterbank from a list of frequencies. |
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[735a739] | 4 | |
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[eff63ab] | 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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[735a739] | 15 | samplerate = 48000 |
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[eff63ab] | 16 | win_s = 2048 |
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[735a739] | 17 | |
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[eff63ab] | 18 | # define a list of custom frequency |
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[735a739] | 19 | freq_list = [60, 80, 200, 400, 800, 1600, 3200, 6400, 12800, 24000] |
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[eff63ab] | 20 | # number of filters to create |
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[735a739] | 21 | n_filters = len(freq_list) - 2 |
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| 22 | |
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[eff63ab] | 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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[735a739] | 26 | f.set_triangle_bands(freqs, samplerate) |
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| 27 | |
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[eff63ab] | 28 | # get the coefficients from the filterbank |
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[735a739] | 29 | coeffs = f.get_coeffs() |
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[eff63ab] | 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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[735a739] | 33 | f.set_coeffs(coeffs) |
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| 34 | |
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[eff63ab] | 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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