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