mirror of
https://github.com/cookiengineer/audacity
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91 lines
2.1 KiB
C++
91 lines
2.1 KiB
C++
/***************************************************/
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/*! \class PitShift
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\brief STK simple pitch shifter effect class.
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This class implements a simple pitch shifter
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using delay lines.
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by Perry R. Cook and Gary P. Scavone, 1995 - 2005.
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*/
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/***************************************************/
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#include "PitShift.h"
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#include <cmath>
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using namespace Nyq;
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const int maxDelay = 5024;
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PitShift :: PitShift()
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{
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delayLength = maxDelay - 24;
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halfLength = delayLength / 2;
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delay_[0] = 12;
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delay_[1] = maxDelay / 2;
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delayLine_[0].setMaximumDelay( maxDelay );
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delayLine_[0].setDelay( delay_[0] );
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delayLine_[1].setMaximumDelay( maxDelay );
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delayLine_[1].setDelay( delay_[1] );
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effectMix_ = 0.5;
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rate_ = 1.0;
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}
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PitShift :: ~PitShift()
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{
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}
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void PitShift :: clear()
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{
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delayLine_[0].clear();
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delayLine_[1].clear();
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lastOutput_[0] = 0.0;
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lastOutput_[1] = 0.0;
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}
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void PitShift :: setShift(StkFloat shift)
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{
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if (shift < 1.0) {
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rate_ = 1.0 - shift;
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}
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else if (shift > 1.0) {
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rate_ = 1.0 - shift;
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}
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else {
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rate_ = 0.0;
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delay_[0] = halfLength+12;
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}
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}
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StkFloat PitShift :: computeSample(StkFloat input)
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{
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// Calculate the two delay length values, keeping them within the
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// range 12 to maxDelay-12.
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delay_[0] += rate_;
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while (delay_[0] > maxDelay-12) delay_[0] -= delayLength;
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while (delay_[0] < 12) delay_[0] += delayLength;
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delay_[1] = delay_[0] + halfLength;
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while (delay_[1] > maxDelay-12) delay_[1] -= delayLength;
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while (delay_[1] < 12) delay_[1] += delayLength;
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// Set the new delay line lengths.
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delayLine_[0].setDelay((long)delay_[0]);
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delayLine_[1].setDelay((long)delay_[1]);
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// Calculate a triangular envelope.
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env_[1] = fabs( (delay_[0] - halfLength + 12) * (1.0 / (halfLength+12) ) );
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env_[0] = 1.0 - env_[1];
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// Delay input and apply envelope.
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lastOutput_[0] = env_[0] * delayLine_[0].tick(input);
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lastOutput_[0] += env_[1] * delayLine_[1].tick(input);
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// Compute effect mix and output.
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lastOutput_[0] *= effectMix_;
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lastOutput_[0] += (1.0 - effectMix_) * input;
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lastOutput_[1] = lastOutput_[0];
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return lastOutput_[0];
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}
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