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STK general finite impulse response filter class. More...
#include <Fir.h>
Public Member Functions | |
Fir (void) | |
Default constructor creates a zero-order pass-through "filter". | |
Fir (std::vector< StkFloat > &coefficients) | |
Overloaded constructor which takes filter coefficients. | |
~Fir (void) | |
Class destructor. | |
void | setCoefficients (std::vector< StkFloat > &coefficients, bool clearState=false) |
Set filter coefficients. | |
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 general finite impulse response filter class.
This class provides a generic digital filter structure that can be used to implement FIR filters. For filters with feedback terms, the Iir class should be used.
In particular, this class implements the standard difference equation:
y[n] = b[0]*x[n] + ... + b[nb]*x[n-nb]
The gain parameter is applied at the filter input and does not affect the coefficient values. The default gain value is 1.0. This structure results in one extra multiply per computed sample, but allows easy control of the overall filter gain.
by Perry R. Cook and Gary P. Scavone, 1995-2011.
stk::Fir::Fir | ( | std::vector< StkFloat > & | coefficients | ) |
Overloaded constructor which takes filter coefficients.
An StkError can be thrown if the coefficient vector size is zero.
void stk::Fir::setCoefficients | ( | std::vector< StkFloat > & | coefficients, | |
bool | clearState = false | |||
) |
Set filter coefficients.
An StkError can be thrown if the coefficient vector size is zero. The internal state of the filter is not cleared unless the clearState flag is true
.
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.
00101 { 00102 #if defined(_STK_DEBUG_) 00103 if ( channel >= frames.channels() ) { 00104 oStream_ << "Fir::tick(): channel and StkFrames arguments are incompatible!"; 00105 handleError( StkError::FUNCTION_ARGUMENT ); 00106 } 00107 #endif 00108 00109 StkFloat *samples = &frames[channel]; 00110 unsigned int i, hop = frames.channels(); 00111 for ( unsigned int j=0; j<frames.frames(); j++, samples += hop ) { 00112 inputs_[0] = gain_ * *samples; 00113 *samples = 0.0; 00114 00115 for ( i=b_.size()-1; i>0; i-- ) { 00116 *samples += b_[i] * inputs_[i]; 00117 inputs_[i] = inputs_[i-1]; 00118 } 00119 *samples += b_[0] * inputs_[0]; 00120 } 00121 00122 lastFrame_[0] = *(samples-hop); 00123 return frames; 00124 }
StkFrames & stk::Fir::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.
00127 { 00128 #if defined(_STK_DEBUG_) 00129 if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) { 00130 oStream_ << "Fir::tick(): channel and StkFrames arguments are incompatible!"; 00131 handleError( StkError::FUNCTION_ARGUMENT ); 00132 } 00133 #endif 00134 00135 StkFloat *iSamples = &iFrames[iChannel]; 00136 StkFloat *oSamples = &oFrames[oChannel]; 00137 unsigned int i, iHop = iFrames.channels(), oHop = oFrames.channels(); 00138 for ( unsigned int j=0; j<iFrames.frames(); j++, iSamples += iHop, oSamples += oHop ) { 00139 inputs_[0] = gain_ * *iSamples; 00140 *oSamples = 0.0; 00141 00142 for ( i=b_.size()-1; i>0; i-- ) { 00143 *oSamples += b_[i] * inputs_[i]; 00144 inputs_[i] = inputs_[i-1]; 00145 } 00146 *oSamples += b_[0] * inputs_[0]; 00147 } 00148 00149 lastFrame_[0] = *(oSamples-oHop); 00150 return iFrames; 00151 }
The Synthesis ToolKit in C++ (STK) |
©1995-2011 Perry R. Cook and Gary P. Scavone. All Rights Reserved. |