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2134
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1 /*
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2 * This file is part of FFmpeg.
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3 *
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4 * FFmpeg 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 * FFmpeg 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 FFmpeg; 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 */
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