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 | Mel-Frequency Cepstrum Coefficients object |
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25 | |
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26 | This object computes MFCC coefficients on an input cvec_t. |
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27 | |
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28 | The implementation follows the specifications established by Malcolm Slaney |
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29 | in its Auditory Toolbox, available online at the following address (see |
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30 | file mfcc.m): |
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31 | |
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32 | https://engineering.purdue.edu/~malcolm/interval/1998-010/ |
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33 | |
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34 | \example spectral/test-mfcc.c |
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35 | |
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36 | */ |
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37 | |
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38 | #ifndef AUBIO_MFCC_H |
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39 | #define AUBIO_MFCC_H |
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40 | |
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41 | #ifdef __cplusplus |
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42 | extern "C" |
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43 | { |
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44 | #endif |
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45 | |
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46 | /** mfcc object */ |
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47 | typedef struct _aubio_mfcc_t aubio_mfcc_t; |
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48 | |
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49 | /** create mfcc object |
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50 | |
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51 | \param buf_size size of analysis buffer (and length the FFT transform) |
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52 | \param samplerate audio sampling rate |
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53 | \param n_coeffs number of desired coefficients |
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54 | \param n_filters number of desired filters |
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55 | |
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56 | */ |
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57 | aubio_mfcc_t *new_aubio_mfcc (uint_t buf_size, |
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58 | uint_t n_filters, uint_t n_coeffs, uint_t samplerate); |
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59 | |
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60 | /** delete mfcc object |
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61 | |
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62 | \param mf mfcc object as returned by new_aubio_mfcc |
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63 | |
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64 | */ |
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65 | void del_aubio_mfcc (aubio_mfcc_t * mf); |
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66 | |
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67 | /** mfcc object processing |
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68 | |
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69 | \param mf mfcc object as returned by new_aubio_mfcc |
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70 | \param in input spectrum (buf_size long) |
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71 | \param out output mel coefficients buffer (n_coeffs long) |
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72 | |
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73 | */ |
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74 | void aubio_mfcc_do (aubio_mfcc_t * mf, const cvec_t * in, fvec_t * out); |
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75 | |
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76 | /** set power parameter |
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77 | |
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78 | \param mf mfcc object, as returned by new_aubio_mfcc() |
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79 | \param power Raise norm of the input spectrum norm to this power before |
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80 | computing filterbank. Defaults to `1`. |
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81 | |
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82 | See aubio_filterbank_set_power(). |
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83 | |
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84 | */ |
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85 | uint_t aubio_mfcc_set_power (aubio_mfcc_t *mf, smpl_t power); |
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86 | |
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87 | /** get power parameter |
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88 | |
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89 | \param mf mfcc object, as returned by new_aubio_mfcc() |
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90 | \return current power parameter. Defaults to `1`. |
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91 | |
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92 | See aubio_filterbank_get_power(). |
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93 | |
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94 | */ |
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95 | uint_t aubio_mfcc_get_power (aubio_mfcc_t *mf); |
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96 | |
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97 | /** set scaling parameter |
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98 | |
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99 | \param mf mfcc object, as returned by new_aubio_mfcc() |
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100 | \param scale Scaling value to apply. |
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101 | |
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102 | Scales the output of the filterbank after taking its logarithm and before |
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103 | computing the DCT. Defaults to `1`. |
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104 | |
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105 | */ |
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106 | uint_t aubio_mfcc_set_scale (aubio_mfcc_t *mf, smpl_t scale); |
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107 | |
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108 | /** get scaling parameter |
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109 | |
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110 | \param mf mfcc object, as returned by new_aubio_mfcc() |
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111 | \return current scaling parameter. Defaults to `1`. |
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112 | |
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113 | */ |
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114 | uint_t aubio_mfcc_get_scale (aubio_mfcc_t *mf); |
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115 | |
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116 | /** Mel filterbank initialization |
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117 | |
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118 | \param mf mfcc object |
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119 | \param fmin start frequency, in Hz |
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120 | \param fmax end frequency, in Hz |
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121 | |
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122 | The filterbank will be initialized with bands linearly spaced in the mel |
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123 | scale, from `fmin` to `fmax`. |
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124 | |
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125 | See also |
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126 | -------- |
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127 | |
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128 | aubio_filterbank_set_mel_coeffs() |
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129 | |
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130 | */ |
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131 | uint_t aubio_mfcc_set_mel_coeffs (aubio_mfcc_t *mf, |
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132 | smpl_t fmin, smpl_t fmax); |
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133 | |
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134 | /** Mel filterbank initialization |
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135 | |
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136 | \param mf mfcc object |
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137 | \param fmin start frequency, in Hz |
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138 | \param fmax end frequency, in Hz |
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139 | |
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140 | The bank of filters will be initalized to to cover linearly spaced bands in |
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141 | the Htk mel scale, from `fmin` to `fmax`. |
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142 | |
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143 | See also |
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144 | -------- |
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145 | |
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146 | aubio_filterbank_set_mel_coeffs_htk() |
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147 | |
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148 | */ |
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149 | uint_t aubio_mfcc_set_mel_coeffs_htk (aubio_mfcc_t *mf, |
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150 | smpl_t fmin, smpl_t fmax); |
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151 | |
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152 | /** Mel filterbank initialization (Auditory Toolbox's parameters) |
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153 | |
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154 | \param mf mfcc object |
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155 | \param samplerate audio sampling rate, in Hz |
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156 | |
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157 | The filter coefficients are built to match exactly Malcolm Slaney's Auditory |
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158 | Toolbox implementation. The number of filters should be 40. |
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159 | |
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160 | This is the default filterbank when `mf` was created with `n_filters = 40`. |
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161 | |
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162 | See also |
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163 | -------- |
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164 | |
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165 | aubio_filterbank_set_mel_coeffs_slaney() |
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166 | |
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167 | */ |
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168 | uint_t aubio_mfcc_set_mel_coeffs_slaney (aubio_mfcc_t *mf); |
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169 | |
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170 | #ifdef __cplusplus |
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171 | } |
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172 | #endif |
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173 | |
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174 | #endif /* AUBIO_MFCC_H */ |
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