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stk::Fir Class Reference

STK general finite impulse response filter class. More...

#include <Fir.h>

Inheritance diagram for stk::Fir:
stk::Filter stk::Stk

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. More...
 
 ~Fir (void)
 Class destructor.
 
void setCoefficients (std::vector< StkFloat > &coefficients, bool clearState=false)
 Set filter coefficients. More...
 
StkFloat lastOut (void) const
 Return the last computed output value.
 
StkFloat tick (StkFloat input)
 Input one sample to the filter and return one output.
 
StkFramestick (StkFrames &frames, unsigned int channel=0)
 Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs. More...
 
StkFramestick (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. More...
 
- Public Member Functions inherited from stk::Filter
 Filter (void)
 Class constructor.
 
unsigned int channelsIn (void) const
 Return the number of input channels for the class.
 
unsigned int channelsOut (void) const
 Return the number of output channels for the class.
 
virtual void clear (void)
 Clears all internal states of the filter.
 
void setGain (StkFloat gain)
 Set the filter gain. More...
 
StkFloat getGain (void) const
 Return the current filter gain.
 
StkFloat phaseDelay (StkFloat frequency)
 Return the filter phase delay at the specified frequency. More...
 
const StkFrameslastFrame (void) const
 Return an StkFrames reference to the last output sample frame.
 
- Public Member Functions inherited from stk::Stk
void ignoreSampleRateChange (bool ignore=true)
 A function to enable/disable the automatic updating of class data when the STK sample rate changes. More...
 

Additional Inherited Members

- Static Public Member Functions inherited from stk::Stk
static StkFloat sampleRate (void)
 Static method that returns the current STK sample rate.
 
static void setSampleRate (StkFloat rate)
 Static method that sets the STK sample rate. More...
 
static std::string rawwavePath (void)
 Static method that returns the current rawwave path.
 
static void setRawwavePath (std::string path)
 Static method that sets the STK rawwave path.
 
static void swap16 (unsigned char *ptr)
 Static method that byte-swaps a 16-bit data type.
 
static void swap32 (unsigned char *ptr)
 Static method that byte-swaps a 32-bit data type.
 
static void swap64 (unsigned char *ptr)
 Static method that byte-swaps a 64-bit data type.
 
static void sleep (unsigned long milliseconds)
 Static cross-platform method to sleep for a number of milliseconds.
 
static bool inRange (StkFloat value, StkFloat min, StkFloat max)
 Static method to check whether a value is within a specified range.
 
static void handleError (const char *message, StkError::Type type)
 Static function for error reporting and handling using c-strings.
 
static void handleError (std::string message, StkError::Type type)
 Static function for error reporting and handling using c++ strings.
 
static void showWarnings (bool status)
 Toggle display of WARNING and STATUS messages.
 
static void printErrors (bool status)
 Toggle display of error messages before throwing exceptions.
 
- Static Public Attributes inherited from stk::Stk
static const StkFormat STK_SINT8
 
static const StkFormat STK_SINT16
 
static const StkFormat STK_SINT24
 
static const StkFormat STK_SINT32
 
static const StkFormat STK_FLOAT32
 
static const StkFormat STK_FLOAT64
 
- Protected Member Functions inherited from stk::Stk
 Stk (void)
 Default constructor.
 
virtual ~Stk (void)
 Class destructor.
 
virtual void sampleRateChanged (StkFloat newRate, StkFloat oldRate)
 This function should be implemented in subclasses that depend on the sample rate.
 
void addSampleRateAlert (Stk *ptr)
 Add class pointer to list for sample rate change notification.
 
void removeSampleRateAlert (Stk *ptr)
 Remove class pointer from list for sample rate change notification.
 
void handleError (StkError::Type type) const
 Internal function for error reporting that assumes message in oStream_ variable.
 

Detailed Description

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, 1995–2014.

Constructor & Destructor Documentation

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.

Member Function Documentation

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.

StkFrames & stk::Fir::tick ( StkFrames frames,
unsigned int  channel = 0 
)
inlinevirtual

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.

101 {
102 #if defined(_STK_DEBUG_)
103  if ( channel >= frames.channels() ) {
104  oStream_ << "Fir::tick(): channel and StkFrames arguments are incompatible!";
105  handleError( StkError::FUNCTION_ARGUMENT );
106  }
107 #endif
108 
109  StkFloat *samples = &frames[channel];
110  unsigned int i, hop = frames.channels();
111  for ( unsigned int j=0; j<frames.frames(); j++, samples += hop ) {
112  inputs_[0] = gain_ * *samples;
113  *samples = 0.0;
114 
115  for ( i=(unsigned int)b_.size()-1; i>0; i-- ) {
116  *samples += b_[i] * inputs_[i];
117  inputs_[i] = inputs_[i-1];
118  }
119  *samples += b_[0] * inputs_[0];
120  }
121 
122  lastFrame_[0] = *(samples-hop);
123  return frames;
124 }
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.

127 {
128 #if defined(_STK_DEBUG_)
129  if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
130  oStream_ << "Fir::tick(): channel and StkFrames arguments are incompatible!";
131  handleError( StkError::FUNCTION_ARGUMENT );
132  }
133 #endif
134 
135  StkFloat *iSamples = &iFrames[iChannel];
136  StkFloat *oSamples = &oFrames[oChannel];
137  unsigned int i, iHop = iFrames.channels(), oHop = oFrames.channels();
138  for ( unsigned int j=0; j<iFrames.frames(); j++, iSamples += iHop, oSamples += oHop ) {
139  inputs_[0] = gain_ * *iSamples;
140  *oSamples = 0.0;
141 
142  for ( i=(unsigned int)b_.size()-1; i>0; i-- ) {
143  *oSamples += b_[i] * inputs_[i];
144  inputs_[i] = inputs_[i-1];
145  }
146  *oSamples += b_[0] * inputs_[0];
147  }
148 
149  lastFrame_[0] = *(oSamples-oHop);
150  return iFrames;
151 }

The documentation for this class was generated from the following file:

The Synthesis ToolKit in C++ (STK)
©1995--2014 Perry R. Cook and Gary P. Scavone. All Rights Reserved.