2 * This file is part of FFmpeg.
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.
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.
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
19 #ifndef AVCODEC_AVFFT_H
20 #define AVCODEC_AVFFT_H
22 typedef float FFTSample;
24 typedef struct FFTComplex {
28 typedef struct FFTContext FFTContext;
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
35 FFTContext *av_fft_init(int nbits, int inverse);
38 * Do the permutation needed BEFORE calling ff_fft_calc().
40 void av_fft_permute(FFTContext *s, FFTComplex *z);
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.
46 void av_fft_calc(FFTContext *s, FFTComplex *z);
48 void av_fft_end(FFTContext *s);
50 FFTContext *av_mdct_init(int nbits, int inverse, double scale);
51 void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
52 void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input);
53 void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
54 void av_mdct_end(FFTContext *s);
56 /* Real Discrete Fourier Transform */
58 enum RDFTransformType {
65 typedef struct RDFTContext RDFTContext;
69 * @param nbits log2 of the length of the input array
70 * @param trans the type of transform
72 RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans);
73 void av_rdft_calc(RDFTContext *s, FFTSample *data);
74 void av_rdft_end(RDFTContext *s);
76 /* Discrete Cosine Transform */
78 typedef struct DCTContext DCTContext;
80 enum DCTTransformType {
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
93 * @note the first element of the input of DST-I is ignored
95 DCTContext *av_dct_init(int nbits, enum DCTTransformType type);
96 void av_dct_calc(DCTContext *s, FFTSample *data);
97 void av_dct_end (DCTContext *s);
99 #endif /* AVCODEC_AVFFT_H */