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avfft.h (3111B)

      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 */