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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_AVFFT_H
#define AVCODEC_AVFFT_H
typedef float FFTSample;
typedef struct FFTComplex {
FFTSample re, im;
} FFTComplex;
typedef struct FFTContext FFTContext;
/**
* Set up a complex FFT.
* @param nbits log2 of the length of the input array
* @param inverse if 0 perform the forward transform, if 1 perform the inverse
*/
FFTContext *av_fft_init(int nbits, int inverse);
/**
* Do the permutation needed BEFORE calling ff_fft_calc().
*/
void av_fft_permute(FFTContext *s, FFTComplex *z);
/**
* Do a complex FFT with the parameters defined in av_fft_init(). The
* input data must be permuted before. No 1.0/sqrt(n) normalization is done.
*/
void av_fft_calc(FFTContext *s, FFTComplex *z);
void av_fft_end(FFTContext *s);
FFTContext *av_mdct_init(int nbits, int inverse, double scale);
void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input);
void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
void av_mdct_end(FFTContext *s);
/* Real Discrete Fourier Transform */
enum RDFTransformType {
DFT_R2C,
IDFT_C2R,
IDFT_R2C,
DFT_C2R,
};
typedef struct RDFTContext RDFTContext;
/**
* Set up a real FFT.
* @param nbits log2 of the length of the input array
* @param trans the type of transform
*/
RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans);
void av_rdft_calc(RDFTContext *s, FFTSample *data);
void av_rdft_end(RDFTContext *s);
/* Discrete Cosine Transform */
typedef struct DCTContext DCTContext;
enum DCTTransformType {
DCT_II = 0,
DCT_III,
DCT_I,
DST_I,
};
/**
* Sets up DCT.
* @param nbits size of the input array:
* (1 << nbits) for DCT-II, DCT-III and DST-I
* (1 << nbits) + 1 for DCT-I
*
* @note the first element of the input of DST-I is ignored
*/
DCTContext *av_dct_init(int nbits, enum DCTTransformType type);
void av_dct_calc(DCTContext *s, FFTSample *data);
void av_dct_end (DCTContext *s);
#endif /* AVCODEC_AVFFT_H */
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