/*

 * 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,

};



/**

 * Set 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 */

