不韋 呂 / F746_SD_GraphicEqualizer

Output the audio signal with filtering by graphic equalizer in the *.wav file on the SD card using onboard CODEC. SD カードの *.wav ファイルのオーディオ信号をグラフィック･イコライザを通して，ボードに搭載されているCODEC で出力する．

Dependencies:   F746_GUI F746_SAI_IO SD_PlayerSkeleton FrequencyResponseDrawer

MyGraphicEqualizer/BiquadGrEq.hpp@24:f78f9d0ac262, 2017-04-10 (annotated)

Committer:
MikamiUitOpen
Date:
Mon Apr 10 04:07:35 2017 +0000
Revision:
24:f78f9d0ac262
Parent:
23:878419f8638b 
25

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 15:ef0acc9fe111 1 //--------------------------------------------------------------
MikamiUitOpen 15:ef0acc9fe111 2 // グラフィックイコライザで使う 1D タイプの 2 次のフィルタ
MikamiUitOpen 15:ef0acc9fe111 3 // Biquad filter of 1D type for graphic equalizer
MikamiUitOpen 15:ef0acc9fe111 4 // このクラスでは，係数は実行中に書き換えられることを想定している
MikamiUitOpen 15:ef0acc9fe111 5 //
MikamiUitOpen 15:ef0acc9fe111 6 // u[n] = x[n] + a1*u[n-1] + a2*u[n-2]
MikamiUitOpen 15:ef0acc9fe111 7 // y[n] = b0*u[n] + b1*u[n-1] + b2*u[n-2]
MikamiUitOpen 15:ef0acc9fe111 8 // x[n] : input signal
MikamiUitOpen 15:ef0acc9fe111 9 // y[n] : output signal
MikamiUitOpen 15:ef0acc9fe111 10 //
MikamiUitOpen 23:878419f8638b 11 // 2017/03/28, Copyright (c) 2017 MIKAMI, Naoki
MikamiUitOpen 15:ef0acc9fe111 12 //--------------------------------------------------------------
MikamiUitOpen 15:ef0acc9fe111 13
MikamiUitOpen 15:ef0acc9fe111 14 #ifndef IIR_BIQUAD_GREQ_HPP
MikamiUitOpen 15:ef0acc9fe111 15 #define IIR_BIQUAD_GREQ_HPP
MikamiUitOpen 15:ef0acc9fe111 16
MikamiUitOpen 15:ef0acc9fe111 17 #include "mbed.h"
MikamiUitOpen 15:ef0acc9fe111 18
MikamiUitOpen 15:ef0acc9fe111 19 // 2nd order IIR filter
MikamiUitOpen 15:ef0acc9fe111 20 namespace Mikami
MikamiUitOpen 15:ef0acc9fe111 21 {
MikamiUitOpen 15:ef0acc9fe111 22 class BiquadGrEq
MikamiUitOpen 15:ef0acc9fe111 23 {
MikamiUitOpen 15:ef0acc9fe111 24 public:
MikamiUitOpen 15:ef0acc9fe111 25 struct Coefs { float a1, a2, b0, b1, b2; };
MikamiUitOpen 15:ef0acc9fe111 26
MikamiUitOpen 23:878419f8638b 27 BiquadGrEq(const Coefs ck = (Coefs){0, 0, 0, 0, 0})
MikamiUitOpen 15:ef0acc9fe111 28 {
MikamiUitOpen 15:ef0acc9fe111 29 SetCoefficients(ck);
MikamiUitOpen 15:ef0acc9fe111 30 Clear();
MikamiUitOpen 15:ef0acc9fe111 31 }
MikamiUitOpen 15:ef0acc9fe111 32
MikamiUitOpen 23:878419f8638b 33 void SetCoefficients(const Coefs cf) { cf_ = cf; }
MikamiUitOpen 15:ef0acc9fe111 34
MikamiUitOpen 15:ef0acc9fe111 35 float Execute(float xn)
MikamiUitOpen 15:ef0acc9fe111 36 {
MikamiUitOpen 23:878419f8638b 37 float un = xn + cf_.a1*un1_ + cf_.a2*un2_;
MikamiUitOpen 23:878419f8638b 38 float yn = cf_.b0*un + cf_.b1*un1_ + cf_.b2*un2_;
MikamiUitOpen 15:ef0acc9fe111 39
MikamiUitOpen 15:ef0acc9fe111 40 un2_ = un1_;
MikamiUitOpen 15:ef0acc9fe111 41 un1_ = un;
MikamiUitOpen 15:ef0acc9fe111 42
MikamiUitOpen 15:ef0acc9fe111 43 return yn;
MikamiUitOpen 15:ef0acc9fe111 44 }
MikamiUitOpen 15:ef0acc9fe111 45
MikamiUitOpen 15:ef0acc9fe111 46 void Clear() { un1_ = un2_ = 0; }
MikamiUitOpen 15:ef0acc9fe111 47
MikamiUitOpen 15:ef0acc9fe111 48 private:
MikamiUitOpen 23:878419f8638b 49 Coefs cf_;
MikamiUitOpen 15:ef0acc9fe111 50 float un1_, un2_;
MikamiUitOpen 15:ef0acc9fe111 51
MikamiUitOpen 15:ef0acc9fe111 52 // disallow copy constructor
MikamiUitOpen 15:ef0acc9fe111 53 BiquadGrEq(const BiquadGrEq&);
MikamiUitOpen 15:ef0acc9fe111 54 };
MikamiUitOpen 15:ef0acc9fe111 55 }
MikamiUitOpen 15:ef0acc9fe111 56 #endif // IIR_BIQUAD_GREQ_HPP