virtualx-engine/servers/audio/effects/eq.h

/*************************************************************************/
/*  eq.h                                                                 */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
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// Author: reduzio@gmail.com (C) 2006

#ifndef EQ_FILTER_H
#define EQ_FILTER_H


#include "typedefs.h"
#include "vector.h"


/**
@author Juan Linietsky
*/

class EQ {
public:

	enum Preset {

		PRESET_6_BANDS,
		PRESET_8_BANDS,
		PRESET_10_BANDS,
		PRESET_21_BANDS,
		PRESET_31_BANDS
	};



	class BandProcess {

	friend class EQ;
		float c1,c2,c3;
		struct History {
			float a1,a2,a3;
			float b1,b2,b3;

		} history;

	public:

		inline void process_one(float & p_data);

		BandProcess();
	};

private:
	struct Band {

		float freq;
		float c1,c2,c3;
	};

	Vector<Band> band;

	float mix_rate;

	void recalculate_band_coefficients();

public:


	void set_mix_rate(float p_mix_rate);

	int get_band_count() const;
	void set_preset_band_mode(Preset p_preset);
	void set_bands(const Vector<float>& p_bands);
	BandProcess get_band_processor(int p_band) const;
	float get_band_frequency(int p_band);

	EQ();
	~EQ();

};


/* Inline Function */

inline void EQ::BandProcess::process_one(float & p_data) {


	history.a1=p_data;

	history.b1=	c1 * ( history.a1 - history.a3 )
			+ c3 * history.b2
			- c2 * history.b3;

	p_data = history.b1;

	history.a3=history.a2;
	history.a2=history.a1;
	history.b3=history.b2;
	history.b2=history.b1;

}


#endif