seiichi horie
Synthesizer based on the Unzen / Nucleo F746ZG
Dependencies: amakusa mbed-dsp mbed shimabara ukifune unzen_nucleo_f746
Fork of
skeleton_unzen_nucleo_f746
by 
seiichi horie
雲仙フレームワークのテストとして作っているプロジェクトです。中身はどんどん変っていきます。 説明はDSP空挺団の「シンセサイザー」カテゴリーを参照してください。初回は「ドッグフードを食べる」です。
Diff: svfilter.cpp
- Revision:
- 20:53021b2c424d
- Child:
- 21:dcfbe6d2a6d3
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/svfilter.cpp Sat Feb 04 15:03:41 2017 +0000
@@ -0,0 +1,101 @@
+#include "signal_processing.h"
+
+//---------------------------------------------------------------------------
+// Reference
+// stanford edu "CCRMA Digital State Variable Filters"
+// https://ccrma.stanford.edu/~jos/svf/
+// musicdsp "State Variable"
+// http://musicdsp.org/archive.php?classid=3#23
+//---------------------------------------------------------------------------
+
+ // State Variable Filter
+ // The f * f_factor must be < Fs/6.
+SVFilter::SVFilter( uint32_t blockSize ) : amakusa::AbstractFilter ( blockSize )
+{
+ this->fc = 440;
+ this->f_factor = 1.0f;
+ this->set_Fs( SAMPLING_FREQUENCY );
+ this->set_Q( 1.414f );
+ this->set_mode( lpf );
+
+ this->d1 = 0.0f;
+ this->d2 = 0.0f;
+}
+
+/************************************************************************
+* +--------------------------------------> hp
+* |
+* | +--------------------> bp
+* | f D1 | f
+* x(n)->(+)-+-|>-(+)->[z^-1]->+-|>->(+)--------+---> lp
+* A | | | |
+* | +<----------+ +<-[z^-1]-+
+* | -q | D2 |
+* (+)<------<|----------+ |
+* | -1 |
+* +<-----------------<|-----------------+
+*
+* bp = D1
+* lp = D1 * f + D2
+* hp = x - q * bp - lp
+*
+* D1 = hp * f + D1
+* D2 = lp
+*
+************************************************************************/
+void SVFilter::run( float32_t *pSrc, float32_t *pDst, uint32_t blockSize )
+{
+ float32_t bp, lp, hp;
+
+ blockSize = blockSize ? blockSize : this->blockSize;
+
+ for ( int i= 0; i<blockSize; i++ )
+ {
+ bp = this->d1;
+ lp = bp * this->f + this->d2;
+ hp = pSrc[i] - this->q * bp - lp;
+
+ this->d1 += hp * this->f;
+ this->d2 = lp;
+ }
+}
+
+
+void SVFilter::set_Q( float32_t Q )
+{
+ if ( Q < 0.1f )
+ Q = 0.1f;
+
+ this->q = 1.0f/Q;
+}
+
+
+void SVFilter::set_Fs( int new_Fs ) // Hz
+{
+ this->Fs = new_Fs;
+ this->update_parameters();
+}
+
+void SVFilter::set_fc( int new_fc ) // Hz
+{
+ this->fc = new_fc;
+ this->f = 2.0f * sin( 3.141592f * this->fc / this->Fs );
+}
+
+
+void SVFilter::set_f_factor( float32_t new_f_factor )
+{
+ this->f_factor = new_f_factor;
+ this->f = 2.0f * sin( 3.141592f * this->fc / this->Fs );
+}
+
+void SVFilter::set_mode( svf_mode new_mode )
+{
+ this->mode = new_mode;
+}
+
+
+void SVFilter::update_parameters( void )
+{
+ this->f = 2.0f * sin( 3.141592f * this->fc * this->f_factor / this->Fs );
+}