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stk::Granulate Class Reference

STK granular synthesis class. More...

#include <Granulate.h>

Inheritance diagram for stk::Granulate:
stk::Generator stk::Stk

Public Member Functions

 Granulate (void)
 Default constructor.
 
 Granulate (unsigned int nVoices, std::string fileName, bool typeRaw=false)
 Constructor taking input audio file and number of voices arguments.
 
 ~Granulate (void)
 Class destructor.
 
void openFile (std::string fileName, bool typeRaw=false)
 Load a monophonic soundfile to be "granulated". More...
 
void reset (void)
 Reset the file pointer and all existing grains to the file start. More...
 
void setVoices (unsigned int nVoices=1)
 Set the number of simultaneous grain "voices" to use. More...
 
void setStretch (unsigned int stretchFactor=1)
 Set the stretch factor used for grain playback (1 - 1000). More...
 
void setGrainParameters (unsigned int duration=30, unsigned int rampPercent=50, int offset=0, unsigned int delay=0)
 Set global grain parameters used to determine individual grain settings. More...
 
void setRandomFactor (StkFloat randomness=0.1)
 This factor is used when setting individual grain parameters (0.0 - 1.0). More...
 
StkFloat lastOut (unsigned int channel=0)
 Return the specified channel value of the last computed frame. More...
 
StkFloat tick (unsigned int channel=0)
 Compute one sample frame and return the specified channel value.
 
StkFramestick (StkFrames &frames, unsigned int channel=0)
 Fill the StkFrames object with computed sample frames, starting at the specified channel. More...
 
- Public Member Functions inherited from stk::Generator
 Generator (void)
 Class constructor.
 
unsigned int channelsOut (void) const
 Return the number of output channels for the class.
 
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 granular synthesis class.

This class implements a real-time granular synthesis algorithm that operates on an input soundfile. Multi-channel files are supported. Various functions are provided to allow control over voice and grain parameters.

The functionality of this class is based on the program MacPod by Chris Rolfe and Damian Keller, though there are likely to be a number of differences in the actual implementation.

by Gary Scavone, 2005 - 2010.

Member Function Documentation

void stk::Granulate::openFile ( std::string  fileName,
bool  typeRaw = false 
)

Load a monophonic soundfile to be "granulated".

An StkError will be thrown if the file is not found, its format is unknown or unsupported, or the file has more than one channel.

void stk::Granulate::reset ( void  )

Reset the file pointer and all existing grains to the file start.

Multiple grains are offset from one another in time by grain duration / nVoices.

void stk::Granulate::setVoices ( unsigned int  nVoices = 1)

Set the number of simultaneous grain "voices" to use.

Multiple grains are offset from one another in time by grain duration / nVoices. For this reason, it is best to set the grain parameters before calling this function (during initialization).

void stk::Granulate::setStretch ( unsigned int  stretchFactor = 1)

Set the stretch factor used for grain playback (1 - 1000).

Granular synthesis allows for time-stetching without affecting the original pitch of a sound. A stretch factor of 4 will produce a resulting sound of length 4 times the orignal sound. The default parameter of 1 produces no stretching.

void stk::Granulate::setGrainParameters ( unsigned int  duration = 30,
unsigned int  rampPercent = 50,
int  offset = 0,
unsigned int  delay = 0 
)

Set global grain parameters used to determine individual grain settings.

Each grain is defined as having a length of duration milliseconds which must be greater than zero. For values of rampPercent (0 - 100) greater than zero, a linear envelope will be applied to each grain. If rampPercent = 100, the resultant grain "window" is triangular while rampPercent = 50 produces a trapezoidal window. In addition, each grain can have a time delay of length delay and a grain pointer increment of length offset, which can be negative, before the next ramp onset (in milliseconds). The offset parameter controls grain pointer jumps between enveloped grain segments, while the delay parameter causes grain calculations to pause between grains. The actual values calculated for each grain will be randomized by a factor set using the setRandomFactor() function.

void stk::Granulate::setRandomFactor ( StkFloat  randomness = 0.1)

This factor is used when setting individual grain parameters (0.0 - 1.0).

This random factor is applied when all grain state durations are calculated. If set to 0.0, no randomness occurs. When randomness = 1.0, a grain segment of length duration will be randomly augmented by up to +- duration seconds (i.e., a 30 millisecond length will be augmented by an extra length of up to +30 or -30 milliseconds).

StkFloat stk::Granulate::lastOut ( unsigned int  channel = 0)
inline

Return the specified channel value of the last computed frame.

The channel argument must be less than the number of output channels, which can be determined with the channelsOut() function (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.

See Also
lastFrame()
175 {
176 #if defined(_STK_DEBUG_)
177  if ( channel >= lastFrame_.channels() ) {
178  oStream_ << "Granulate::lastOut(): channel argument is invalid!";
179  handleError( StkError::FUNCTION_ARGUMENT );
180  }
181 #endif
182 
183  return lastFrame_[channel];
184 }
StkFrames & stk::Granulate::tick ( StkFrames frames,
unsigned int  channel = 0 
)
inlinevirtual

Fill the StkFrames object with computed sample frames, starting at the specified channel.

The channel argument plus the number of output channels 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::Generator.

187 {
188  unsigned int nChannels = lastFrame_.channels();
189 #if defined(_STK_DEBUG_)
190  if ( channel > frames.channels() - nChannels ) {
191  oStream_ << "Granulate::tick(): channel and StkFrames arguments are incompatible!";
192  handleError( StkError::FUNCTION_ARGUMENT );
193  }
194 #endif
195 
196  StkFloat *samples = &frames[channel];
197  unsigned int j, hop = frames.channels() - nChannels;
198  for ( unsigned int i=0; i<frames.frames(); i++, samples += hop ) {
199  *samples++ = tick();
200  for ( j=1; j<nChannels; j++ )
201  *samples++ = lastFrame_[j];
202  }
203 
204  return frames;
205 }

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.