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avfft.h (2909B)

      1 /*
      2 * This file is part of Libav.
      3 *
      4 * Libav 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 * Libav 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 Libav; 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 typedef float FFTSample;
     23 
     24 typedef struct FFTComplex {
     25    FFTSample re, im;
     26 } FFTComplex;
     27 
     28 typedef 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 */
     35 FFTContext *av_fft_init(int nbits, int inverse);
     36 
     37 /**
     38 * Do the permutation needed BEFORE calling ff_fft_calc().
     39 */
     40 void 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 */
     46 void av_fft_calc(FFTContext *s, FFTComplex *z);
     47 
     48 void av_fft_end(FFTContext *s);
     49 
     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);
     55 
     56 /* Real Discrete Fourier Transform */
     57 
     58 enum RDFTransformType {
     59    DFT_R2C,
     60    IDFT_C2R,
     61    IDFT_R2C,
     62    DFT_C2R,
     63 };
     64 
     65 typedef 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 */
     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);
     75 
     76 /* Discrete Cosine Transform */
     77 
     78 typedef struct DCTContext DCTContext;
     79 
     80 enum DCTTransformType {
     81    DCT_II = 0,
     82    DCT_III,
     83    DCT_I,
     84    DST_I,
     85 };
     86 
     87 /**
     88 * Set 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 */
     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);
     98 
     99 #endif /* AVCODEC_AVFFT_H */