ffmpeg/libavcodec/avfft.h

   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 */