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1 /* |
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2 * This file is part of Libav. |
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3 * |
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4 * Libav is free software; you can redistribute it and/or |
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5 * modify it under the terms of the GNU Lesser General Public |
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6 * License as published by the Free Software Foundation; either |
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7 * version 2.1 of the License, or (at your option) any later version. |
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8 * |
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9 * Libav is distributed in the hope that it will be useful, |
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10 * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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12 * Lesser General Public License for more details. |
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13 * |
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14 * You should have received a copy of the GNU Lesser General Public |
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15 * License along with Libav; if not, write to the Free Software |
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16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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17 */ |
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18 |
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19 #ifndef AVCODEC_AVFFT_H |
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20 #define AVCODEC_AVFFT_H |
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21 |
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22 /** |
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23 * @file |
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24 * @ingroup lavc_fft |
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25 * FFT functions |
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26 */ |
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27 |
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28 /** |
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29 * @defgroup lavc_fft FFT functions |
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30 * @ingroup lavc_misc |
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31 * |
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32 * @{ |
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33 */ |
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34 |
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35 typedef float FFTSample; |
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36 |
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37 typedef struct FFTComplex { |
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38 FFTSample re, im; |
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39 } FFTComplex; |
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40 |
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41 typedef struct FFTContext FFTContext; |
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42 |
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43 /** |
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44 * Set up a complex FFT. |
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45 * @param nbits log2 of the length of the input array |
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46 * @param inverse if 0 perform the forward transform, if 1 perform the inverse |
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47 */ |
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48 FFTContext *av_fft_init(int nbits, int inverse); |
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49 |
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50 /** |
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51 * Do the permutation needed BEFORE calling ff_fft_calc(). |
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52 */ |
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53 void av_fft_permute(FFTContext *s, FFTComplex *z); |
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54 |
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55 /** |
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56 * Do a complex FFT with the parameters defined in av_fft_init(). The |
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57 * input data must be permuted before. No 1.0/sqrt(n) normalization is done. |
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58 */ |
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59 void av_fft_calc(FFTContext *s, FFTComplex *z); |
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60 |
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61 void av_fft_end(FFTContext *s); |
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62 |
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63 FFTContext *av_mdct_init(int nbits, int inverse, double scale); |
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64 void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input); |
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65 void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input); |
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66 void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input); |
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67 void av_mdct_end(FFTContext *s); |
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68 |
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69 /* Real Discrete Fourier Transform */ |
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70 |
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71 enum RDFTransformType { |
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72 DFT_R2C, |
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73 IDFT_C2R, |
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74 IDFT_R2C, |
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75 DFT_C2R, |
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76 }; |
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77 |
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78 typedef struct RDFTContext RDFTContext; |
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79 |
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80 /** |
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81 * Set up a real FFT. |
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82 * @param nbits log2 of the length of the input array |
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83 * @param trans the type of transform |
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84 */ |
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85 RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans); |
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86 void av_rdft_calc(RDFTContext *s, FFTSample *data); |
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87 void av_rdft_end(RDFTContext *s); |
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88 |
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89 /* Discrete Cosine Transform */ |
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90 |
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91 typedef struct DCTContext DCTContext; |
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92 |
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93 enum DCTTransformType { |
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94 DCT_II = 0, |
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95 DCT_III, |
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96 DCT_I, |
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97 DST_I, |
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98 }; |
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99 |
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100 /** |
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101 * Set up DCT. |
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102 * @param nbits size of the input array: |
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103 * (1 << nbits) for DCT-II, DCT-III and DST-I |
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104 * (1 << nbits) + 1 for DCT-I |
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105 * |
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106 * @note the first element of the input of DST-I is ignored |
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107 */ |
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108 DCTContext *av_dct_init(int nbits, enum DCTTransformType type); |
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109 void av_dct_calc(DCTContext *s, FFTSample *data); |
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110 void av_dct_end (DCTContext *s); |
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111 |
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112 /** |
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113 * @} |
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114 */ |
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115 |
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116 #endif /* AVCODEC_AVFFT_H */ |