1 | /* |
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2 | Copyright (C) 2018 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 | #include "aubio_priv.h" |
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22 | #include "musicutils.h" |
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23 | |
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24 | smpl_t |
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25 | aubio_hztomel (smpl_t freq) |
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26 | { |
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27 | const smpl_t lin_space = 3./200.; |
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28 | const smpl_t split_hz = 1000.; |
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29 | const smpl_t split_mel = split_hz * lin_space; |
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30 | const smpl_t log_space = 27./LOG(6400/1000.); |
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31 | if (freq < 0) { |
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32 | AUBIO_WRN("hztomel: input frequency should be >= 0\n"); |
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33 | return 0; |
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34 | } |
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35 | if (freq < split_hz) |
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36 | { |
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37 | return freq * lin_space; |
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38 | } else { |
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39 | return split_mel + log_space * LOG (freq / split_hz); |
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40 | } |
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41 | |
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42 | } |
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43 | |
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44 | smpl_t |
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45 | aubio_meltohz (smpl_t mel) |
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46 | { |
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47 | const smpl_t lin_space = 200./3.; |
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48 | const smpl_t split_hz = 1000.; |
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49 | const smpl_t split_mel = split_hz / lin_space; |
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50 | const smpl_t logSpacing = POW(6400/1000., 1/27.); |
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51 | if (mel < 0) { |
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52 | AUBIO_WRN("meltohz: input mel should be >= 0\n"); |
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53 | return 0; |
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54 | } |
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55 | if (mel < split_mel) { |
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56 | return lin_space * mel; |
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57 | } else { |
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58 | return split_hz * POW(logSpacing, mel - split_mel); |
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59 | } |
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60 | } |
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61 | |
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62 | smpl_t |
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63 | aubio_hztomel_htk (smpl_t freq) |
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64 | { |
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65 | const smpl_t split_hz = 700.; |
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66 | const smpl_t log_space = 1127.; |
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67 | if (freq < 0) { |
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68 | AUBIO_WRN("hztomel_htk: input frequency should be >= 0\n"); |
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69 | return 0; |
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70 | } |
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71 | return log_space * LOG (1 + freq / split_hz); |
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72 | } |
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73 | |
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74 | smpl_t |
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75 | aubio_meltohz_htk (smpl_t mel) |
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76 | { |
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77 | const smpl_t split_hz = 700.; |
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78 | const smpl_t log_space = 1./1127.; |
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79 | if (mel < 0) { |
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80 | AUBIO_WRN("meltohz_htk: input frequency should be >= 0\n"); |
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81 | return 0; |
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82 | } |
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83 | return split_hz * ( EXP ( mel * log_space) - 1.); |
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84 | } |
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85 | |
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