boting ren / Mbed 2 deprecated F746_SD_GraphicEqualizer_ren0620

revised version of F746_SD_GraphicEqualizer

Dependencies:   BSP_DISCO_F746NG F746_GUI F746_SAI_IO FrequencyResponseDrawer LCD_DISCO_F746NG SDFileSystem_Warning_Fixed TS_DISCO_F746NG mbed

Fork of F746_SD_GraphicEqualizer by 不韋 呂

MyClasses_Functions/GrEqParamsCalculator.hpp

Committer:
MikamiUitOpen
Date:
2016-05-09
Revision:
8:12aa05f3cc24

File content as of revision 8:12aa05f3cc24:

//------------------------------------------------------------------------------
//  Parameters calculator class of buquad unit for graphic equalizer
//  グラフィックイコライザで使う biquad フィルタの係数を計算するクラス
//
//   2016/05/09, Copyright (c) 2016 MIKAMI, Naoki
//------------------------------------------------------------------------------

#ifndef GRAPHIC_EQALIZER_PARAMETER_CALCULATOR_HPP
#define GRAPHIC_EQALIZER_PARAMETER_CALCULATOR_HPP

#include "mbed.h"
#include "BiquadGrEq.hpp"

namespace Mikami
{
    class GrEqParams
    {
    public:
        // Constructor
        GrEqParams(int bands, float fs) : BANDS_(bands), FS_(fs) {}

        // 係数を計算する
        BiquadGrEq::Coefs Execute(int band, float f0, float gDb, float qVal)
        {
            const float PI = 3.1415926536f;
            BiquadGrEq::Coefs coefs;
            
            float gSqrt = sqrtf(powf(10, gDb/20.0f));
            float w0 = 2.0f*PI*f0/FS_;
            
            if ( (band != 0) && (band != BANDS_-1) )
            {
                float alpha = sinf(w0)/(2.0f*qVal);
                float a0 = 1.0f + alpha/gSqrt;
                coefs.a1 = 2.0f*cosf(w0)/a0;
                coefs.a2 = -(1.0f - alpha/gSqrt)/a0;
                coefs.b0 = (1.0f + alpha*gSqrt)/a0;
                coefs.b1 = -coefs.a1;
                coefs.b2 = (1.0f - alpha*gSqrt)/a0;
            }
            else
            {
                w0 = (band == 0) ? w0*1.414f : w0/1.414f;
                float alpha = sinf(w0)/sqrtf(2.0f); // Q = 1/sqrt(2)
                float g_a = sqrtf(gSqrt);
                float cosW0 = cosf(w0);
                float gSqrtP1 = gSqrt+1.0f;
                float gSqrtM1 = gSqrt-1.0f;
                if (band == 0)
                {                   
                    float a0 = gSqrtP1 + gSqrtM1*cosW0
                               + 2.0f*g_a*alpha;
                    coefs.a1 = 2.0f*(gSqrtM1 + gSqrtP1*cosW0)/a0;
                    coefs.a2 = -(gSqrtP1 + gSqrtM1*cosW0
                               - 2.0f*g_a*alpha)/a0;
                    coefs.b0 = gSqrt*(gSqrtP1 - gSqrtM1*cosW0
                               + 2.0f*g_a*alpha)/a0;
                    coefs.b1 = 2.0f*gSqrt*(gSqrtM1
                               - gSqrtP1*cosW0)/a0;
                    coefs.b2 = gSqrt*(gSqrtP1 - gSqrtM1*cosW0
                               - 2.0f*g_a*alpha)/a0;
                }
                else
                {
                    float a0 = gSqrtP1 - gSqrtM1*cosW0
                               + 2.0f*g_a*alpha;
                    coefs.a1 = -2.0f*(gSqrtM1 - gSqrtP1*cosW0)/a0;
                    coefs.a2 = -(gSqrtP1 - gSqrtM1*cosW0
                               - 2.0f*g_a*alpha)/a0;
                    coefs.b0 = gSqrt*(gSqrtP1 + gSqrtM1*cosW0
                               + 2.0f*g_a*alpha)/a0;
                    coefs.b1 = -2.0f*gSqrt*(gSqrtM1 + gSqrtP1*cosW0)/a0;
                    coefs.b2 = gSqrt*(gSqrtP1 + gSqrtM1*cosW0
                               - 2.0f*g_a*alpha)/a0;
                }
            }

            return coefs;
        }

    private:
        const int BANDS_;
        const float FS_;
    };
}
#endif  // GRAPHIC_EQALIZER_PARAMETER_CALCULATOR_HPP