@saintmatthieu I’m fairly sure I’ve made some changes since my original post. See below the updated code. Planning at some point soon to give rubber band v3 a try to have selectable formant. I expect the cpu use will shoot up though. This code itself is pretty bad on cpu (subjective as users seem happy with it being low cpu) when shifting up as its optimised for really low latency - it is however in a commercial product.
David
#include "RingBuffer.h"
class PitchShifter
{
public:
/** Setup the pitch shifter. By default the shifter will be setup so that the dry signal isn't delayed to be given a somewhat similar latency to the wet signal - this is not accurate when enabled! By enabling minLatency some latency can be reduced with the expense of potential tearing during modulation with a change of the pitch parameter.
*/
PitchShifter(int numChannels, double sampleRate, int samplesPerBlock)
{
rubberband = std::make_unique<RubberBand::RubberBandStretcher>(sampleRate, numChannels, RubberBand::RubberBandStretcher::Option::OptionProcessRealTime + RubberBand::RubberBandStretcher::Option::OptionPitchHighConsistency + RubberBand::RubberBandStretcher::Option::OptionTransientsSmooth + RubberBand::RubberBandStretcher::Option::OptionPhaseIndependent + RubberBand::RubberBandStretcher::Option::OptionFormantPreserved + RubberBand::RubberBandStretcher::Option::OptionChannelsTogether + RubberBand::RubberBandStretcher::Option::OptionWindowShort + RubberBand::RubberBandStretcher::Option::OptionEngineFaster, 1.0, 1.0);
initLatency = (int) rubberband->getLatency();
maxSamples = sampleRate / 1000.0 * 4.0;
input.initialise(numChannels, sampleRate);
output.initialise(numChannels, sampleRate);
for (int sample = 0; sample < rubberband->getPreferredStartPad(); ++sample) { // Loop to push samples to input buffer.
for (int channel = 0; channel < numChannels; channel++) {
input.pushSample(0.0, channel);
}
}
samplesToSkip = (int) rubberband->getStartDelay();
juce::dsp::ProcessSpec spec;
spec.maximumBlockSize = samplesPerBlock;
spec.numChannels = numChannels;
spec.sampleRate = sampleRate;
timeSmoothing.reset(sampleRate, 0.05);
mixSmoothing.reset(sampleRate, 0.1);
pitchSmoothing.reset(sampleRate, 0.0);
pitchSmoothing.setCurrentAndTargetValue(1.0);
timeSmoothing.setCurrentAndTargetValue(1.0);
smallestAcceptableSize = maxSamples * 0.5;
largestAcceptableSize = maxSamples * 1.5;
latencyInSamples = (initLatency + maxSamples);
dryWet = std::make_unique<juce::dsp::DryWetMixer<float>>(latencyInSamples * 2);
dryWet->prepare(spec);
dryWet->setWetLatency(latencyInSamples);
formantPreserving = true;
}
~PitchShifter()
{
}
void setFormantPreserving(bool shouldPreserveFormants)
{
if (shouldPreserveFormants != formantPreserving) {
formantPreserving = shouldPreserveFormants;
rubberband->setFormantOption((shouldPreserveFormants) ? RubberBand::RubberBandStretcher::Option::OptionFormantPreserved : RubberBand::RubberBandStretcher::Option::OptionFormantShifted);
}
}
int getLatency()
{
return latencyInSamples;
}
/** Pitch shift a juce::AudioBuffer<float>
*/
void processBuffer (juce::dsp::AudioBlock<float>& block)
{
pitchSmoothing.setTargetValue(powf(2.0, pitchParam / 12)); // Convert semitone value into pitch scale value.
if (!pitchSmoothing.isSmoothing())
{
if (pitchSmoothing.getCurrentValue() <= 1.0)
{
smallestAcceptableSize = maxSamples * 0.5;
largestAcceptableSize = maxSamples * 1.5;
} else if (pitchSmoothing.getCurrentValue() > 1.0)
{
smallestAcceptableSize = maxSamples * 0.5;
largestAcceptableSize = maxSamples * 2.5;
}
}
dryWet->pushDrySamples(block);
for (int sample = 0; sample < block.getNumSamples(); ++sample) { // Loop to push samples to input buffer.
for (int channel = 0; channel < block.getNumChannels(); channel++) {
input.pushSample(block.getSample(channel, sample), channel);
block.setSample(channel, sample, 0.0);
if (channel == block.getNumChannels() - 1) {
reqSamples = rubberband->getSamplesRequired();
if (reqSamples <= input.getAvailableSamples(0)) { // Check to trigger rubberband to process when full enough.
readSpace = output.getAvailableSamples(0);
if (readSpace < smallestAcceptableSize) { // Compress or stretch time when output ring buffer is too full or empty.
timeSmoothing.setTargetValue(1.1);
} else if (readSpace > largestAcceptableSize) {
timeSmoothing.setTargetValue(0.9);
} else {
timeSmoothing.setTargetValue(1.0);
}
rubberband->setTimeRatio(timeSmoothing.skip((int) reqSamples));
newPitch = pitchSmoothing.skip((int) reqSamples);
if (oldPitch != newPitch)
{
rubberband->setPitchScale(newPitch);
oldPitch = newPitch;
}
rubberband->process(input.readPointerArray((int) reqSamples), reqSamples, false); // Process stored input samples.
}
}
}
}
auto availableSamples = rubberband->available();
if (availableSamples > 0) { // If rubberband samples are available then copy to the output ring buffer.
rubberband->retrieve(output.writePointerArray(), availableSamples);
output.copyToBuffer(availableSamples);
}
auto availableOutputSamples = output.getAvailableSamples(0) - samplesToSkip; // Copy samples from output ring buffer to output buffer where available.
if (samplesToSkip > 0)
{
int thisSkip = juce::jmin(output.getAvailableSamples(0), samplesToSkip);
for (int sample = 0; sample < thisSkip; ++sample)
{
for (int channel = 0; channel < block.getNumChannels(); ++channel)
{
output.popSample(channel);
}
samplesToSkip--;
}
}
for (int channel = 0; channel < block.getNumChannels(); ++channel) {
for (int sample = 0; sample < block.getNumSamples(); ++sample) {
if (output.getAvailableSamples(channel) > 0) {
block.setSample(channel, (int) ((availableOutputSamples >= block.getNumSamples()) ? sample : sample + block.getNumSamples() - availableOutputSamples), output.popSample(channel));
}
}
}
if (pitchParam == 0 && mixParam != 100.0) { // Ensure no phasing with mix occurs when pitch is set to +/-0 semitones.
mixSmoothing.setTargetValue(0.0);
} else
{
mixSmoothing.setTargetValue(mixParam/100.0);
}
dryWet->setWetMixProportion(mixSmoothing.skip((int) block.getNumSamples()));
dryWet->mixWetSamples(block); // Mix in the dry signal.
}
/** Set the wet/dry mix as a % value.
*/
void setMixPercentage(float newPercentage)
{
mixParam = newPercentage;
}
/** Set the pitch shift in semitones.
*/
void setSemitoneShift(float newShift)
{
pitchParam = newShift;
smallestAcceptableSize = maxSamples * 10.0;
largestAcceptableSize = maxSamples * 20.0;
}
/** Get the % value of the wet/dry mix.
*/
float getMixPercentage()
{
return mixParam;
}
/** Get the pitch shift in semitones.
*/
float getSemitoneShift()
{
return pitchParam;
}
/** Get the estimated latency. This is an average guess of latency with no pitch shifting but can vary by a few buffers. Changing the pitch shift can cause less or more latency.
*/
int getLatencyEstimationInSamples()
{
return maxSamples * 3.0 + initLatency;
}
private:
std::unique_ptr<RubberBand::RubberBandStretcher> rubberband;
RingBuffer input, output;
int maxSamples, initLatency, bufferFail, smallestAcceptableSize, largestAcceptableSize;
float oldPitch, pitchParam, mixParam, newPitch;
std::unique_ptr<juce::dsp::DryWetMixer<float>> dryWet;
juce::SmoothedValue<float> timeSmoothing, mixSmoothing, pitchSmoothing;
bool formantPreserving;
int latencyInSamples = 0, samplesToSkip = 0, readSpace;
size_t reqSamples;
};