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stk::Twang Class Reference

STK enhanced plucked string class. More...

#include <Twang.h>

Inheritance diagram for stk::Twang:
stk::Stk

Public Member Functions

 Twang (StkFloat lowestFrequency=50.0)
 Class constructor, taking the lowest desired playing frequency.
 
void clear (void)
 Reset and clear all internal state.
 
void setLowestFrequency (StkFloat frequency)
 Set the delayline parameters to allow frequencies as low as specified.
 
void setFrequency (StkFloat frequency)
 Set the delayline parameters for a particular frequency.
 
void setPluckPosition (StkFloat position)
 Set the pluck or "excitation" position along the string (0.0 - 1.0).
 
void setLoopGain (StkFloat loopGain)
 Set the nominal loop gain. More...
 
void setLoopFilter (std::vector< StkFloat > coefficients)
 Set the loop filter coefficients. More...
 
StkFloat lastOut (void)
 Return an StkFrames reference to the last output sample frame. More...
 
StkFloat tick (StkFloat input)
 Compute and return one output sample.
 
StkFramestick (StkFrames &frames, unsigned int channel=0)
 Take a channel of the iFrames object as inputs to the class and write outputs to the oFrames object. 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 effect and write outputs to the oFrames object. 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 enhanced plucked string class.

This class implements an enhanced plucked-string physical model, a la Jaffe-Smith, Smith, Karjalainen and others. It includes a comb filter to simulate pluck position. The tick() function takes an input sample, which is added to the delayline input. This can be used to implement commuted synthesis (if the input samples are derived from the impulse response of a body filter) and/or feedback (as in an electric guitar model).

This is a digital waveguide model, making its use possibly subject to patents held by Stanford University, Yamaha, and others.

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

Member Function Documentation

void stk::Twang::setLoopGain ( StkFloat  loopGain)

Set the nominal loop gain.

The actual loop gain is based on the value set with this function, but scaled slightly according to the frequency. Higher frequency settings have greater loop gains because of high-frequency loop-filter roll-off.

void stk::Twang::setLoopFilter ( std::vector< StkFloat >  coefficients)

Set the loop filter coefficients.

The loop filter can be any arbitrary FIR filter. By default, the coefficients are set for a first-order lowpass filter with coefficients b = [0.5 0.5].

StkFloat stk::Twang::lastOut ( void  )
inline

Return an StkFrames reference to the last output sample frame.

Return the last computed output value.

74 { return lastOutput_; };
StkFrames & stk::Twang::tick ( StkFrames frames,
unsigned int  channel = 0 
)
inline

Take a channel of the iFrames object as inputs to the class 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.

123 {
124 #if defined(_STK_DEBUG_)
125  if ( channel >= frames.channels() ) {
126  oStream_ << "Twang::tick(): channel and StkFrames arguments are incompatible!";
127  handleError( StkError::FUNCTION_ARGUMENT );
128  }
129 #endif
130 
131  StkFloat *samples = &frames[channel];
132  unsigned int hop = frames.channels();
133  for ( unsigned int i=0; i<frames.frames(); i++, samples += hop )
134  *samples = tick( *samples );
135 
136  return frames;
137 }
StkFrames & stk::Twang::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 effect 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.

140 {
141 #if defined(_STK_DEBUG_)
142  if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
143  oStream_ << "Twang::tick(): channel and StkFrames arguments are incompatible!";
144  handleError( StkError::FUNCTION_ARGUMENT );
145  }
146 #endif
147 
148  StkFloat *iSamples = &iFrames[iChannel];
149  StkFloat *oSamples = &oFrames[oChannel];
150  unsigned int iHop = iFrames.channels(), oHop = oFrames.channels();
151  for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop )
152  *oSamples = tick( *iSamples );
153 
154  return iFrames;
155 }

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.