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
22typedef float FFTSample;
23
24typedef struct FFTComplex {
25    FFTSample re, im;
26} FFTComplex;
27
28typedef struct FFTContext FFTContext;
29
30/**
31 * Set up a complex FFT.
32 * @param nbits           log2 of the length of the input array
33 * @param inverse         if 0 perform the forward transform, if 1 perform the inverse
34 */
35FFTContext *av_fft_init(int nbits, int inverse);
36
37/**
38 * Do the permutation needed BEFORE calling ff_fft_calc().
39 */
40void av_fft_permute(FFTContext *s, FFTComplex *z);
41
42/**
43 * Do a complex FFT with the parameters defined in av_fft_init(). The
44 * input data must be permuted before. No 1.0/sqrt(n) normalization is done.
45 */
46void av_fft_calc(FFTContext *s, FFTComplex *z);
47
48void av_fft_end(FFTContext *s);
49
50FFTContext *av_mdct_init(int nbits, int inverse, double scale);
51void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
52void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input);
53void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
54void av_mdct_end(FFTContext *s);
55
56/* Real Discrete Fourier Transform */
57
58enum RDFTransformType {
59    DFT_R2C,
60    IDFT_C2R,
61    IDFT_R2C,
62    DFT_C2R,
63};
64
65typedef struct RDFTContext RDFTContext;
66
67/**
68 * Set up a real FFT.
69 * @param nbits           log2 of the length of the input array
70 * @param trans           the type of transform
71 */
72RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans);
73void av_rdft_calc(RDFTContext *s, FFTSample *data);
74void av_rdft_end(RDFTContext *s);
75
76/* Discrete Cosine Transform */
77
78typedef struct DCTContext DCTContext;
79
80enum DCTTransformType {
81    DCT_II = 0,
82    DCT_III,
83    DCT_I,
84    DST_I,
85};
86
87/**
88 * Sets up DCT.
89 * @param nbits           size of the input array:
90 *                        (1 << nbits)     for DCT-II, DCT-III and DST-I
91 *                        (1 << nbits) + 1 for DCT-I
92 *
93 * @note the first element of the input of DST-I is ignored
94 */
95DCTContext *av_dct_init(int nbits, enum DCTTransformType type);
96void av_dct_calc(DCTContext *s, FFTSample *data);
97void av_dct_end (DCTContext *s);
98
99#endif /* AVCODEC_AVFFT_H */
100