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STK one-pole filter class. More...
#include <OnePole.h>
Public Member Functions | |
OnePole (StkFloat thePole=0.9) | |
The default constructor creates a low-pass filter (pole at z = 0.9). | |
~OnePole () | |
Class destructor. | |
void | setB0 (StkFloat b0) |
Set the b[0] coefficient value. | |
void | setA1 (StkFloat a1) |
Set the a[1] coefficient value. | |
void | setCoefficients (StkFloat b0, StkFloat a1, bool clearState=false) |
Set all filter coefficients. | |
void | setPole (StkFloat thePole) |
Set the pole position in the z-plane. | |
StkFloat | lastOut (void) const |
Return the last computed output value. | |
StkFloat | tick (StkFloat input) |
Input one sample to the filter and return one output. | |
StkFrames & | tick (StkFrames &frames, unsigned int channel=0) |
Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs. | |
StkFrames & | tick (StkFrames &iFrames, StkFrames &oFrames, unsigned int iChannel=0, unsigned int oChannel=0) |
Take a channel of the iFrames object as inputs to the filter and write outputs to the oFrames object. |
STK one-pole filter class.
This class implements a one-pole digital filter. A method is provided for setting the pole position along the real axis of the z-plane while maintaining a constant peak filter gain.
by Perry R. Cook and Gary P. Scavone, 1995-2011.
void stk::OnePole::setPole | ( | StkFloat | thePole | ) |
Set the pole position in the z-plane.
This method sets the pole position along the real-axis of the z-plane and normalizes the coefficients for a maximum gain of one. A positive pole value produces a low-pass filter, while a negative pole value produces a high-pass filter. This method does not affect the filter gain value. The argument magnitude should be less than one to maintain filter stability.
Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.
The StkFrames argument reference is returned. The channel
argument must be less than the number of channels in the StkFrames argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an StkError exception.
Implements stk::Filter.
00090 { 00091 #if defined(_STK_DEBUG_) 00092 if ( channel >= frames.channels() ) { 00093 oStream_ << "OnePole::tick(): channel and StkFrames arguments are incompatible!"; 00094 handleError( StkError::FUNCTION_ARGUMENT ); 00095 } 00096 #endif 00097 00098 StkFloat *samples = &frames[channel]; 00099 unsigned int hop = frames.channels(); 00100 for ( unsigned int i=0; i<frames.frames(); i++, samples += hop ) { 00101 inputs_[0] = gain_ * *samples; 00102 *samples = b_[0] * inputs_[0] - a_[1] * outputs_[1]; 00103 outputs_[1] = *samples; 00104 } 00105 00106 lastFrame_[0] = outputs_[1]; 00107 return frames; 00108 }
StkFrames & stk::OnePole::tick | ( | StkFrames & | iFrames, | |
StkFrames & | oFrames, | |||
unsigned int | iChannel = 0 , |
|||
unsigned int | oChannel = 0 | |||
) | [inline] |
Take a channel of the iFrames
object as inputs to the filter and write outputs to the oFrames
object.
The iFrames
object reference is returned. Each channel argument must be less than the number of channels in the corresponding StkFrames argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an StkError exception.
00111 { 00112 #if defined(_STK_DEBUG_) 00113 if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) { 00114 oStream_ << "OnePole::tick(): channel and StkFrames arguments are incompatible!"; 00115 handleError( StkError::FUNCTION_ARGUMENT ); 00116 } 00117 #endif 00118 00119 StkFloat *iSamples = &iFrames[iChannel]; 00120 StkFloat *oSamples = &oFrames[oChannel]; 00121 unsigned int iHop = iFrames.channels(), oHop = oFrames.channels(); 00122 for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop ) { 00123 inputs_[0] = gain_ * *iSamples; 00124 *oSamples = b_[0] * inputs_[0] - a_[1] * outputs_[1]; 00125 outputs_[1] = *oSamples; 00126 } 00127 00128 lastFrame_[0] = outputs_[1]; 00129 return iFrames; 00130 }
The Synthesis ToolKit in C++ (STK) |
©1995-2011 Perry R. Cook and Gary P. Scavone. All Rights Reserved. |