EQ.h

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/*
 * This file is part of the Wave Arts VQE library.
 * Copyright (C) 2011 Wave Arts, Inc. (http://wavearts.com)
 *
 * VQE 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 2 of the License, or
 * (at your option) any later version.
 *
 * VQE 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.
 *
 * A copy of the GNU General Public License is included with VQE,
 * and can be found online at <http://www.gnu.org/licenses/>.
 *
 * If you'd like to distribute a closed-source product which uses VQE,
 * you must obtain a commercial VQE license from Wave Arts.
 */


#ifndef _EQ_H
#define _EQ_H

#include <stddef.h>

/*
 * EQ state type. Double precision required even at moderate sampling rates (48kHz).
 */
typedef double EqState;

#ifndef PI
#define PI      3.14159265358979323
#endif

/*
 * Direct form II first and second order coefficient structures.
 * Double precision is required for high sampling rates.
 */
typedef double EqCoeffType;

typedef struct {
        EqCoeffType b0;
        EqCoeffType b1;
        EqCoeffType a1;
} Eq1Coeff;

typedef struct {
        EqCoeffType b0;
        EqCoeffType b1;
        EqCoeffType b2;
        EqCoeffType a1;
        EqCoeffType a2;
} Eq2Coeff;

#ifdef  __cplusplus
extern "C" {
#endif

/*
 * Mapping functions from parameters to coefficients.
 * fs:  sampling rate
 * f0:  center or cutoff frequency
 * H:   height in dB
 * W:   width in octaves
 * g:   filter gain
 */
Eq1Coeff EqMap1P1ZHighPass(float fs, float f0, float g);
Eq2Coeff EqMap2P2ZHighPass(float fs, float f0, float g);
Eq2Coeff EqMapBandPass(float fs, float f0, float W, float g);
Eq2Coeff EqMapLowShelf2(float fs, float f0, float H, float gain);
Eq2Coeff EqMapHighShelf2(float fs, float f0, float H, float gain);
Eq2Coeff EqMap2P2ZLowPass(float fs, float f0, float g);

/*
 * Processing functions.
 */
void Eq2ProcNoInterp(float *in, float *out, size_t n, Eq2Coeff *coeff, EqState *state);
void Eq2MxProcNoInterp(int nchl, float **in, float **out, size_t n, Eq2Coeff *coeff, EqState **state);
void Eq2MxILeafProcNoInterp(int nchl, float *in, float *out, size_t n0, Eq2Coeff *coeff, EqState **state);

#ifdef  __cplusplus
}
#endif

#endif  /* _EQ_H */