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STK linear interpolating delay line class. More...
#include <DelayL.h>
Public Member Functions | |
DelayL (StkFloat delay=0.0, unsigned long maxDelay=4095) | |
Default constructor creates a delay-line with maximum length of 4095 samples and zero delay. | |
~DelayL () | |
Class destructor. | |
unsigned long | getMaximumDelay (void) |
Get the maximum delay-line length. | |
void | setMaximumDelay (unsigned long delay) |
Set the maximum delay-line length. | |
void | setDelay (StkFloat delay) |
Set the delay-line length. | |
StkFloat | getDelay (void) const |
Return the current delay-line length. | |
StkFloat | tapOut (unsigned long tapDelay) |
Return the value at tapDelay samples from the delay-line input. | |
void | tapIn (StkFloat value, unsigned long tapDelay) |
Set the value at tapDelay samples from the delay-line input. | |
StkFloat | lastOut (void) const |
Return the last computed output value. | |
StkFloat | nextOut (void) |
Return the value which will be output by the next call to tick(). | |
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 linear interpolating delay line class.
This class implements a fractional-length digital delay-line using first-order linear interpolation. If the delay and maximum length are not specified during instantiation, a fixed maximum length of 4095 and a delay of zero is set.
Linear interpolation is an efficient technique for achieving fractional delay lengths, though it does introduce high-frequency signal attenuation to varying degrees depending on the fractional delay setting. The use of higher order Lagrange interpolators can typically improve (minimize) this attenuation characteristic.
by Perry R. Cook and Gary P. Scavone, 1995-2011.
stk::DelayL::DelayL | ( | StkFloat | delay = 0.0 , |
|
unsigned long | maxDelay = 4095 | |||
) |
Default constructor creates a delay-line with maximum length of 4095 samples and zero delay.
An StkError will be thrown if the delay parameter is less than zero, the maximum delay parameter is less than one, or the delay parameter is greater than the maxDelay value.
void stk::DelayL::setMaximumDelay | ( | unsigned long | delay | ) |
Set the maximum delay-line length.
This method should generally only be used during initial setup of the delay line. If it is used between calls to the tick() function, without a call to clear(), a signal discontinuity will likely occur. If the current maximum length is greater than the new length, no memory allocation change is made.
void stk::DelayL::setDelay | ( | StkFloat | delay | ) |
Set the delay-line length.
The valid range for delay is from 0 to the maximum delay-line length.
StkFloat stk::DelayL::tapOut | ( | unsigned long | tapDelay | ) |
Return the value at tapDelay samples from the delay-line input.
The tap point is determined modulo the delay-line length and is relative to the last input value (i.e., a tapDelay of zero returns the last input value).
StkFloat stk::DelayL::nextOut | ( | void | ) | [inline] |
Return the value which will be output by the next call to tick().
This method is valid only for delay settings greater than zero!
00121 { 00122 if ( doNextOut_ ) { 00123 // First 1/2 of interpolation 00124 nextOutput_ = inputs_[outPoint_] * omAlpha_; 00125 // Second 1/2 of interpolation 00126 if (outPoint_+1 < inputs_.size()) 00127 nextOutput_ += inputs_[outPoint_+1] * alpha_; 00128 else 00129 nextOutput_ += inputs_[0] * alpha_; 00130 doNextOut_ = false; 00131 } 00132 00133 return nextOutput_; 00134 }
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.
00155 { 00156 #if defined(_STK_DEBUG_) 00157 if ( channel >= frames.channels() ) { 00158 oStream_ << "DelayL::tick(): channel and StkFrames arguments are incompatible!"; 00159 handleError( StkError::FUNCTION_ARGUMENT ); 00160 } 00161 #endif 00162 00163 StkFloat *samples = &frames[channel]; 00164 unsigned int hop = frames.channels(); 00165 for ( unsigned int i=0; i<frames.frames(); i++, samples += hop ) { 00166 inputs_[inPoint_++] = *samples * gain_; 00167 if ( inPoint_ == inputs_.size() ) inPoint_ = 0; 00168 *samples = nextOut(); 00169 doNextOut_ = true; 00170 if ( ++outPoint_ == inputs_.size() ) outPoint_ = 0; 00171 } 00172 00173 lastFrame_[0] = *(samples-hop); 00174 return frames; 00175 }
StkFrames & stk::DelayL::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.
00178 { 00179 #if defined(_STK_DEBUG_) 00180 if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) { 00181 oStream_ << "DelayL::tick(): channel and StkFrames arguments are incompatible!"; 00182 handleError( StkError::FUNCTION_ARGUMENT ); 00183 } 00184 #endif 00185 00186 StkFloat *iSamples = &iFrames[iChannel]; 00187 StkFloat *oSamples = &oFrames[oChannel]; 00188 unsigned int iHop = iFrames.channels(), oHop = oFrames.channels(); 00189 for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop ) { 00190 inputs_[inPoint_++] = *iSamples * gain_; 00191 if ( inPoint_ == inputs_.size() ) inPoint_ = 0; 00192 *oSamples = nextOut(); 00193 doNextOut_ = true; 00194 if ( ++outPoint_ == inputs_.size() ) outPoint_ = 0; 00195 } 00196 00197 lastFrame_[0] = *(oSamples-oHop); 00198 return iFrames; 00199 }
The Synthesis ToolKit in C++ (STK) |
©1995-2011 Perry R. Cook and Gary P. Scavone. All Rights Reserved. |