1 | /* |
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2 | Copyright (C) 2007-2013 Paul Brossier <piem@aubio.org> |
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3 | and Amaury Hazan <ahazan@iua.upf.edu> |
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4 | |
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5 | This file is part of aubio. |
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6 | |
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7 | aubio is free software: you can redistribute it and/or modify |
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8 | it under the terms of the GNU General Public License as published by |
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9 | the Free Software Foundation, either version 3 of the License, or |
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10 | (at your option) any later version. |
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11 | |
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12 | aubio is distributed in the hope that it will be useful, |
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13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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15 | GNU General Public License for more details. |
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16 | |
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17 | You should have received a copy of the GNU General Public License |
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18 | along with aubio. If not, see <http://www.gnu.org/licenses/>. |
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19 | |
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20 | */ |
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21 | |
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22 | /** \file |
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23 | |
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24 | Filterbank object coefficients initialization |
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25 | |
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26 | Functions to create set the ::aubio_filterbank_t coefficients to |
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27 | - ::aubio_filterbank_set_triangle_bands: overlapping triangular bands, |
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28 | - ::aubio_filterbank_set_mel_coeffs_slaney: Mel frequency bands. |
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29 | |
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30 | \example spectral/test-filterbank_mel.c |
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31 | |
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32 | */ |
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33 | |
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34 | #ifndef AUBIO_FILTERBANK_MEL_H |
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35 | #define AUBIO_FILTERBANK_MEL_H |
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36 | |
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37 | #ifdef __cplusplus |
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38 | extern "C" |
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39 | { |
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40 | #endif |
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41 | |
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42 | /** filterbank initialization with triangular and overlapping bands |
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43 | |
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44 | \param fb filterbank object |
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45 | \param freqs arbitrary array of boundary frequencies |
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46 | \param samplerate audio sampling rate |
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47 | |
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48 | This function computes the coefficients of the filterbank based on the |
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49 | boundaries found in freqs, in Hz, and using triangular overlapping bands. |
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50 | |
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51 | */ |
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52 | uint_t aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb, |
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53 | const fvec_t * freqs, smpl_t samplerate); |
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54 | |
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55 | /** filterbank initialization for Mel filters using Slaney's coefficients |
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56 | |
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57 | \param fb filterbank object |
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58 | \param samplerate audio sampling rate, in Hz |
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59 | |
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60 | The filter coefficients are built to match exactly Malcolm Slaney's Auditory |
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61 | Toolbox implementation (see file mfcc.m). The number of filters should be 40. |
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62 | |
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63 | References |
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64 | ---------- |
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65 | |
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66 | Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010* |
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67 | https://engineering.purdue.edu/~malcolm/interval/1998-010/ |
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68 | |
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69 | */ |
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70 | uint_t aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb, |
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71 | smpl_t samplerate); |
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72 | |
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73 | /** Mel filterbank initialization |
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74 | |
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75 | \param fb filterbank object |
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76 | \param samplerate audio sampling rate |
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77 | \param fmin start frequency, in Hz |
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78 | \param fmax end frequency, in Hz |
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79 | |
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80 | The filterbank will be initialized with bands linearly spaced in the mel |
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81 | scale, from `fmin` to `fmax`. |
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82 | |
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83 | References |
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84 | ---------- |
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85 | |
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86 | Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010* |
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87 | https://engineering.purdue.edu/~malcolm/interval/1998-010/ |
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88 | |
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89 | */ |
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90 | uint_t aubio_filterbank_set_mel_coeffs(aubio_filterbank_t * fb, |
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91 | smpl_t samplerate, smpl_t fmin, smpl_t fmax); |
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92 | |
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93 | /** Mel filterbank initialization |
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94 | |
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95 | \param fb filterbank object |
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96 | \param samplerate audio sampling rate |
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97 | \param fmin start frequency, in Hz |
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98 | \param fmax end frequency, in Hz |
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99 | |
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100 | The bank of filters will be initalized to to cover linearly spaced bands in |
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101 | the Htk mel scale, from `fmin` to `fmax`. |
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102 | |
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103 | References |
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104 | ---------- |
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105 | |
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106 | Douglas O'Shaughnessy (1987). *Speech communication: human and machine*. |
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107 | Addison-Wesley. p. 150. ISBN 978-0-201-16520-3. |
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108 | |
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109 | HTK Speech Recognition Toolkit: http://htk.eng.cam.ac.uk/ |
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110 | |
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111 | */ |
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112 | uint_t aubio_filterbank_set_mel_coeffs_htk(aubio_filterbank_t * fb, |
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113 | smpl_t samplerate, smpl_t fmin, smpl_t fmax); |
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114 | |
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115 | #ifdef __cplusplus |
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116 | } |
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117 | #endif |
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118 | |
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119 | #endif /* AUBIO_FILTERBANK_MEL_H */ |
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