scummvm/math/mdct.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
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// Based on xoreos' (I)RDFT code which is in turn
// Based upon the (I)MDCT code in FFmpeg
// Copyright (c) 2002 Fabrice Bellard


#ifndef MATH_MDCT_H
#define MATH_MDCT_H

#include "common/scummsys.h"

namespace Math {

class FFT;

/** (Inverse) Modified Discrete Cosine Transforms. */
class MDCT {
public:
	MDCT(int bits, bool inverse, double scale);
	~MDCT();

	/** Compute MDCT of size N = 2^nbits. */
	void calcMDCT(float *output, const float *input);

	/** Compute inverse MDCT of size N = 2^nbits. */
	void calcIMDCT(float *output, const float *input);

private:
	int _bits;
	int _size;

	float *_tCos;
	float *_tSin;

	FFT *_fft;

	/** Compute the middle half of the inverse MDCT of size N = 2^nbits,
	 *  thus excluding the parts that can be derived by symmetry.
	 */
	void calcHalfIMDCT(float *output, const float *input);
};

} // End of namespace Math

#endif // MATH_MDCT_H