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stk::Filter Class Referenceabstract

STK abstract filter class. More...

#include <Filter.h>

Inheritance diagram for stk::Filter:
stk::Stk stk::BiQuad stk::Delay stk::DelayA stk::DelayL stk::Fir stk::FormSwep stk::Iir stk::OnePole stk::OneZero stk::PoleZero stk::TapDelay stk::TwoPole stk::TwoZero

Public Member Functions

 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.
 
virtual StkFramestick (StkFrames &frames, unsigned int channel=0)=0
 Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs. More...
 
- 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 abstract filter class.

This class provides limited common functionality for STK digital filter subclasses. It is general enough to support both monophonic and polyphonic input/output classes.

by Perry R. Cook and Gary P. Scavone, 1995–2014.

Member Function Documentation

void stk::Filter::setGain ( StkFloat  gain)
inline

Set the filter gain.

The gain is applied at the filter input and does not affect the coefficient values. The default gain value is 1.0.

42 { gain_ = gain; };
StkFloat stk::Filter::phaseDelay ( StkFloat  frequency)
inline

Return the filter phase delay at the specified frequency.

Note that the phase delay calculation accounts for the filter gain. The frequency value should be greater than 0.0 and less than or equal to one-half the sample rate.

94 {
95  if ( frequency <= 0.0 || frequency > 0.5 * Stk::sampleRate() ) {
96  oStream_ << "Filter::phaseDelay: argument (" << frequency << ") is out of range!";
97  handleError( StkError::WARNING ); return 0.0;
98  }
99 
100  StkFloat omegaT = 2 * PI * frequency / Stk::sampleRate();
101  StkFloat real = 0.0, imag = 0.0;
102  for ( unsigned int i=0; i<b_.size(); i++ ) {
103  real += b_[i] * std::cos( i * omegaT );
104  imag -= b_[i] * std::sin( i * omegaT );
105  }
106  real *= gain_;
107  imag *= gain_;
108 
109  StkFloat phase = atan2( imag, real );
110 
111  real = 0.0, imag = 0.0;
112  for ( unsigned int i=0; i<a_.size(); i++ ) {
113  real += a_[i] * std::cos( i * omegaT );
114  imag -= a_[i] * std::sin( i * omegaT );
115  }
116 
117  phase -= std::atan2( imag, real );
118  phase = std::fmod( -phase, 2 * PI );
119  return phase / omegaT;
120 }
virtual StkFrames& stk::Filter::tick ( StkFrames frames,
unsigned int  channel = 0 
)
pure virtual

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.

Implemented in stk::Delay, stk::BiQuad, stk::DelayA, stk::Iir, stk::DelayL, stk::TapDelay, stk::FormSwep, stk::TwoPole, stk::PoleZero, stk::TwoZero, stk::Fir, stk::OnePole, and stk::OneZero.


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.