TimeAndPitch.h

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//
// Arbitrary time and pitch stretching, based on the Phase-locked Vocoder.
//
#pragma once
 
#include <complex>
#include <functional>
#include <memory>
#include <vector>
 
namespace staffpad {
 
class TimeAndPitch
{
public:
  using ShiftTimbreCb = std::function<void(
     double factor, std::complex<float>* spectrum, const float* magnitude)>;
 
  TimeAndPitch(
     int fftSize, bool reduceImaging = true, ShiftTimbreCb shiftTimbreCb = {});
  ~TimeAndPitch();
  void setup(int numChannels, int maxBlockSize);
 
  void setTimeStretchAndPitchFactor(double timeStretch, double pitchFactor);
 
  int getSamplesToNextHop() const;
 
  int getNumAvailableOutputSamples() const;
 
  void feedAudio(const float* const* in_smp, int numSamples);
 
  void retrieveAudio(float* const* out_smp, int numSamples);
 
  void processPitchShift(float* const* smp, int numSamples, double pitchFactor);
 
  int getLatencySamples() const;
 
  int getLatencySamplesForStretchRatio(float timeStretch) const;
 
  void reset();
 
private:
  const int fftSize;
  static constexpr int overlap = 4;
  static constexpr bool normalize_window = true; // compensate for ola window overlaps
  static constexpr bool modulate_synthesis_hop = true;
 
  void _process_hop(int hop_a, int hop_s);
  template <int num_channels>
  void _time_stretch(float hop_a, float hop_s);
  void _applyImagingReduction();
 
  struct impl;
  std::shared_ptr<impl> d;
 
  const bool _reduceImaging;
  const ShiftTimbreCb _shiftTimbreCb;
 
  int _numChannels = 1;
  int _maxBlockSize = 1024;
  double _resampleReadPos = 0.0;
  int _availableOutputSamples = 0;
  int _numBins = fftSize / 2 + 1;
  double _overlap_a = overlap;
 
  int _analysis_hop_counter = 0;
 
  double _expectedPhaseChangePerBinPerSample = 0.01;
  double _timeStretch = 1.0;
  double _pitchFactor = 1.0;
 
  int _outBufferWriteOffset = 0;
};
 
} // namespace staffpad