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1 | /* |
2 | * This file is part of FFmpeg. | |
3 | * | |
4 | * FFmpeg is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU Lesser General Public | |
6 | * License as published by the Free Software Foundation; either | |
7 | * version 2.1 of the License, or (at your option) any later version. | |
8 | * | |
9 | * FFmpeg is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | * Lesser General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU Lesser General Public | |
15 | * License along with FFmpeg; if not, write to the Free Software | |
16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
17 | */ | |
18 | ||
19 | #ifndef AVCODEC_AVFFT_H | |
20 | #define AVCODEC_AVFFT_H | |
21 | ||
22 | /** | |
23 | * @file | |
24 | * @ingroup lavc_fft | |
25 | * FFT functions | |
26 | */ | |
27 | ||
28 | /** | |
29 | * @defgroup lavc_fft FFT functions | |
30 | * @ingroup lavc_misc | |
31 | * | |
32 | * @{ | |
33 | */ | |
34 | ||
35 | typedef float FFTSample; | |
36 | ||
37 | typedef struct FFTComplex { | |
38 | FFTSample re, im; | |
39 | } FFTComplex; | |
40 | ||
41 | typedef struct FFTContext FFTContext; | |
42 | ||
43 | /** | |
44 | * Set up a complex FFT. | |
45 | * @param nbits log2 of the length of the input array | |
46 | * @param inverse if 0 perform the forward transform, if 1 perform the inverse | |
47 | */ | |
48 | FFTContext *av_fft_init(int nbits, int inverse); | |
49 | ||
50 | /** | |
51 | * Do the permutation needed BEFORE calling ff_fft_calc(). | |
52 | */ | |
53 | void av_fft_permute(FFTContext *s, FFTComplex *z); | |
54 | ||
55 | /** | |
56 | * Do a complex FFT with the parameters defined in av_fft_init(). The | |
57 | * input data must be permuted before. No 1.0/sqrt(n) normalization is done. | |
58 | */ | |
59 | void av_fft_calc(FFTContext *s, FFTComplex *z); | |
60 | ||
61 | void av_fft_end(FFTContext *s); | |
62 | ||
63 | FFTContext *av_mdct_init(int nbits, int inverse, double scale); | |
64 | void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input); | |
65 | void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input); | |
66 | void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input); | |
67 | void av_mdct_end(FFTContext *s); | |
68 | ||
69 | /* Real Discrete Fourier Transform */ | |
70 | ||
71 | enum RDFTransformType { | |
72 | DFT_R2C, | |
73 | IDFT_C2R, | |
74 | IDFT_R2C, | |
75 | DFT_C2R, | |
76 | }; | |
77 | ||
78 | typedef struct RDFTContext RDFTContext; | |
79 | ||
80 | /** | |
81 | * Set up a real FFT. | |
82 | * @param nbits log2 of the length of the input array | |
83 | * @param trans the type of transform | |
84 | */ | |
85 | RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans); | |
86 | void av_rdft_calc(RDFTContext *s, FFTSample *data); | |
87 | void av_rdft_end(RDFTContext *s); | |
88 | ||
89 | /* Discrete Cosine Transform */ | |
90 | ||
91 | typedef struct DCTContext DCTContext; | |
92 | ||
93 | enum DCTTransformType { | |
94 | DCT_II = 0, | |
95 | DCT_III, | |
96 | DCT_I, | |
97 | DST_I, | |
98 | }; | |
99 | ||
100 | /** | |
101 | * Set up DCT. | |
102 | * | |
103 | * @param nbits size of the input array: | |
104 | * (1 << nbits) for DCT-II, DCT-III and DST-I | |
105 | * (1 << nbits) + 1 for DCT-I | |
106 | * @param type the type of transform | |
107 | * | |
108 | * @note the first element of the input of DST-I is ignored | |
109 | */ | |
110 | DCTContext *av_dct_init(int nbits, enum DCTTransformType type); | |
111 | void av_dct_calc(DCTContext *s, FFTSample *data); | |
112 | void av_dct_end (DCTContext *s); | |
113 | ||
114 | /** | |
115 | * @} | |
116 | */ | |
117 | ||
118 | #endif /* AVCODEC_AVFFT_H */ |