1 | /* |
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2 | Copyright (C) 2003-2015 Paul Brossier <piem@aubio.org> |
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3 | |
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4 | This file is part of aubio. |
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5 | |
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6 | aubio is free software: you can redistribute it and/or modify |
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7 | it under the terms of the GNU General Public License as published by |
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8 | the Free Software Foundation, either version 3 of the License, or |
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9 | (at your option) any later version. |
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10 | |
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11 | aubio is distributed in the hope that it will be useful, |
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12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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14 | GNU General Public License for more details. |
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15 | |
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16 | You should have received a copy of the GNU General Public License |
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17 | along with aubio. If not, see <http://www.gnu.org/licenses/>. |
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18 | |
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19 | */ |
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20 | |
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21 | /** @file |
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22 | * various functions useful in audio signal processing |
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23 | */ |
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24 | |
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25 | #ifndef AUBIO_MUSICUTILS_H |
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26 | #define AUBIO_MUSICUTILS_H |
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27 | |
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28 | #ifdef __cplusplus |
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29 | extern "C" { |
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30 | #endif |
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31 | |
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32 | /** create window |
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33 | |
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34 | \param window_type type of the window to create |
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35 | \param size length of the window to create (see fvec_set_window()) |
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36 | |
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37 | */ |
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38 | fvec_t *new_aubio_window (char_t * window_type, uint_t size); |
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39 | |
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40 | /** set elements of a vector to window coefficients |
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41 | |
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42 | \param window exsting ::fvec_t to use |
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43 | \param window_type type of the window to create |
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44 | |
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45 | List of available window types: "rectangle", "hamming", "hanning", |
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46 | "hanningz", "blackman", "blackman_harris", "gaussian", "welch", "parzen", |
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47 | "default". |
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48 | |
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49 | "default" is equivalent to "hanningz". |
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50 | |
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51 | References: |
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52 | |
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53 | - <a href="http://en.wikipedia.org/wiki/Window_function">Window |
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54 | function</a> on Wikipedia |
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55 | - Amalia de Götzen, Nicolas Bernardini, and Daniel Arfib. Traditional (?) |
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56 | implementations of a phase vocoder: the tricks of the trade. In Proceedings of |
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57 | the International Conference on Digital Audio Effects (DAFx-00), pages 37–44, |
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58 | Uni- versity of Verona, Italy, 2000. |
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59 | (<a href="http://www.cs.princeton.edu/courses/archive/spr09/cos325/Bernardini.pdf"> |
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60 | pdf</a>) |
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61 | |
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62 | */ |
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63 | uint_t fvec_set_window (fvec_t * window, char_t * window_type); |
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64 | |
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65 | /** compute the principal argument |
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66 | |
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67 | This function maps the input phase to its corresponding value wrapped in the |
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68 | range \f$ [-\pi, \pi] \f$. |
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69 | |
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70 | \param phase unwrapped phase to map to the unit circle |
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71 | |
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72 | \return equivalent phase wrapped to the unit circle |
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73 | |
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74 | */ |
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75 | smpl_t aubio_unwrap2pi (smpl_t phase); |
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76 | |
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77 | /** convert frequency bin to midi value */ |
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78 | smpl_t aubio_bintomidi (smpl_t bin, smpl_t samplerate, smpl_t fftsize); |
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79 | |
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80 | /** convert midi value to frequency bin */ |
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81 | smpl_t aubio_miditobin (smpl_t midi, smpl_t samplerate, smpl_t fftsize); |
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82 | |
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83 | /** convert frequency bin to frequency (Hz) */ |
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84 | smpl_t aubio_bintofreq (smpl_t bin, smpl_t samplerate, smpl_t fftsize); |
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85 | |
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86 | /** convert frequency (Hz) to frequency bin */ |
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87 | smpl_t aubio_freqtobin (smpl_t freq, smpl_t samplerate, smpl_t fftsize); |
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88 | |
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89 | /** convert frequency (Hz) to mel |
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90 | |
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91 | \param freq input frequency, in Hz |
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92 | |
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93 | \return output mel |
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94 | |
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95 | Converts a scalar from the frequency domain to the mel scale using Slaney |
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96 | Auditory Toolbox's implementation: |
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97 | |
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98 | If \f$ f < 1000 \f$, \f$ m = 3 f / 200 \f$. |
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99 | |
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100 | If \f$ f >= 1000 \f$, \f$ m = 1000 + 27 \frac{{ln}(f) - ln(1000))} |
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101 | {{ln}(6400) - ln(1000)} |
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102 | \f$ |
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103 | |
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104 | See also |
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105 | -------- |
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106 | |
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107 | aubio_meltohz(), aubio_hztomel_htk(). |
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108 | |
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109 | */ |
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110 | smpl_t aubio_hztomel (smpl_t freq); |
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111 | |
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112 | /** convert mel to frequency (Hz) |
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113 | |
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114 | \param mel input mel |
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115 | |
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116 | \return output frequency, in Hz |
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117 | |
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118 | Converts a scalar from the mel scale to the frequency domain using Slaney |
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119 | Auditory Toolbox's implementation: |
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120 | |
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121 | If \f$ f < 1000 \f$, \f$ f = 200 m/3 \f$. |
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122 | |
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123 | If \f$ f \geq 1000 \f$, \f$ f = 1000 + \left(\frac{6400}{1000}\right) |
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124 | ^{\frac{m - 1000}{27}} \f$ |
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125 | |
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126 | See also |
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127 | -------- |
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128 | |
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129 | aubio_hztomel(), aubio_meltohz_htk(). |
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130 | |
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131 | References |
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132 | ---------- |
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133 | |
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134 | Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010* |
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135 | https://engineering.purdue.edu/~malcolm/interval/1998-010/ |
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136 | |
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137 | */ |
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138 | smpl_t aubio_meltohz (smpl_t mel); |
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139 | |
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140 | /** convert frequency (Hz) to mel |
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141 | |
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142 | \param freq input frequency, in Hz |
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143 | |
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144 | \return output mel |
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145 | |
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146 | Converts a scalar from the frequency domain to the mel scale, using the |
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147 | equation defined by O'Shaughnessy, as implemented in the HTK speech |
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148 | recognition toolkit: |
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149 | |
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150 | \f$ m = 1127 + ln(1 + \frac{f}{700}) \f$ |
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151 | |
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152 | See also |
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153 | -------- |
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154 | |
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155 | aubio_meltohz_htk(), aubio_hztomel(). |
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156 | |
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157 | References |
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158 | ---------- |
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159 | |
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160 | Douglas O'Shaughnessy (1987). *Speech communication: human and machine*. |
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161 | Addison-Wesley. p. 150. ISBN 978-0-201-16520-3. |
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162 | |
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163 | HTK Speech Recognition Toolkit: http://htk.eng.cam.ac.uk/ |
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164 | |
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165 | */ |
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166 | smpl_t aubio_hztomel_htk (smpl_t freq); |
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167 | |
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168 | /** convert mel to frequency (Hz) |
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169 | |
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170 | \param mel input mel |
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171 | |
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172 | \return output frequency, in Hz |
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173 | |
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174 | Converts a scalar from the mel scale to the frequency domain, using the |
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175 | equation defined by O'Shaughnessy, as implemented in the HTK speech |
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176 | recognition toolkit: |
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177 | |
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178 | \f$ f = 700 * {e}^\left(\frac{f}{1127} - 1\right) \f$ |
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179 | |
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180 | See also |
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181 | -------- |
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182 | |
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183 | aubio_hztomel_htk(), aubio_meltohz(). |
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184 | |
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185 | */ |
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186 | smpl_t aubio_meltohz_htk (smpl_t mel); |
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187 | |
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188 | /** convert frequency (Hz) to midi value (0-128) */ |
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189 | smpl_t aubio_freqtomidi (smpl_t freq); |
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190 | |
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191 | /** convert midi value (0-128) to frequency (Hz) */ |
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192 | smpl_t aubio_miditofreq (smpl_t midi); |
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193 | |
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194 | /** clean up cached memory at the end of program |
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195 | |
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196 | This function should be used at the end of programs to purge all cached |
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197 | memory. So far it is only useful to clean FFTW's cache. |
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198 | |
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199 | */ |
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200 | void aubio_cleanup (void); |
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201 | |
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202 | /** zero-crossing rate (ZCR) |
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203 | |
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204 | The zero-crossing rate is the number of times a signal changes sign, |
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205 | divided by the length of this signal. |
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206 | |
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207 | \param v vector to compute ZCR from |
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208 | |
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209 | \return zero-crossing rate of v |
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210 | |
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211 | */ |
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212 | smpl_t aubio_zero_crossing_rate (fvec_t * v); |
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213 | |
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214 | /** compute sound level on a linear scale |
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215 | |
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216 | This gives the average of the square amplitudes. |
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217 | |
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218 | \param v vector to compute level from |
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219 | |
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220 | \return level of v |
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221 | |
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222 | */ |
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223 | smpl_t aubio_level_lin (const fvec_t * v); |
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224 | |
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225 | /** compute sound pressure level (SPL) in dB |
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226 | |
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227 | This quantity is often wrongly called 'loudness'. |
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228 | |
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229 | This gives ten times the log10 of the average of the square amplitudes. |
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230 | |
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231 | \param v vector to compute dB SPL from |
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232 | |
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233 | \return level of v in dB SPL |
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234 | |
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235 | */ |
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236 | smpl_t aubio_db_spl (const fvec_t * v); |
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237 | |
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238 | /** check if buffer level in dB SPL is under a given threshold |
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239 | |
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240 | \param v vector to get level from |
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241 | \param threshold threshold in dB SPL |
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242 | |
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243 | \return 0 if level is under the given threshold, 1 otherwise |
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244 | |
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245 | */ |
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246 | uint_t aubio_silence_detection (const fvec_t * v, smpl_t threshold); |
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247 | |
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248 | /** get buffer level if level >= threshold, 1. otherwise |
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249 | |
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250 | \param v vector to get level from |
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251 | \param threshold threshold in dB SPL |
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252 | |
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253 | \return level in dB SPL if level >= threshold, 1. otherwise |
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254 | |
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255 | */ |
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256 | smpl_t aubio_level_detection (const fvec_t * v, smpl_t threshold); |
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257 | |
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258 | /** clamp the values of a vector within the range [-abs(max), abs(max)] |
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259 | |
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260 | \param in vector to clamp |
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261 | \param absmax maximum value over which input vector elements should be clamped |
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262 | |
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263 | */ |
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264 | void fvec_clamp(fvec_t *in, smpl_t absmax); |
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265 | |
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266 | #ifdef __cplusplus |
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267 | } |
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268 | #endif |
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269 | |
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270 | #endif /* AUBIO_MUSICUTILS_H */ |
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