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
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