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 */ 119