Signalsmith-Audio/signalsmith-stretch
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Formant shifts include tonality limit

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Geraint 2025-04-18 19:45:38 +01:00
parent 5e50132c96
commit 004a52b30d
1 changed files with 16 additions and 9 deletions
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23
signalsmith-stretch.h
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@ -115,12 +115,13 @@ struct SignalsmithStretch {
void setFormantFactor(Sample multiplier, bool compensatePitch=false) { void setFormantFactor(Sample multiplier, bool compensatePitch=false) {
formantMultiplier = multiplier; formantMultiplier = multiplier;
invFormantMultiplier = 1/multiplier;
formantCompensation = compensatePitch; formantCompensation = compensatePitch;
} }
void setFormantSemitones(Sample semitones, bool compensatePitch=false) { void setFormantSemitones(Sample semitones, bool compensatePitch=false) {
setFormantFactor(std::pow(2, semitones/12), compensatePitch); setFormantFactor(std::pow(2, semitones/12), compensatePitch);
} }
// 0 means attempting to detect the pitch // Rough guesstimate of the fundamental frequency, used for formant analysis. 0 means attempting to detect the pitch
void setFormantBase(Sample baseFreq=0) { void setFormantBase(Sample baseFreq=0) {
formantBaseFreq = baseFreq; formantBaseFreq = baseFreq;
} }
@ -425,7 +426,7 @@ private:
std::function<Sample(Sample)> customFreqMap = nullptr; std::function<Sample(Sample)> customFreqMap = nullptr;
bool formantCompensation = false; // compensate for pitch/freq change bool formantCompensation = false; // compensate for pitch/freq change
Sample formantMultiplier = 1; Sample formantMultiplier = 1, invFormantMultiplier = 1;
using STFT = signalsmith::linear::DynamicSTFT<Sample, false, true>; using STFT = signalsmith::linear::DynamicSTFT<Sample, false, true>;
STFT stft; STFT stft;
@ -759,8 +760,7 @@ private:
Sample mapFreq(Sample freq) const { Sample mapFreq(Sample freq) const {
if (customFreqMap) return customFreqMap(freq); if (customFreqMap) return customFreqMap(freq);
if (freq > freqTonalityLimit) { if (freq > freqTonalityLimit) {
Sample diff = freq - freqTonalityLimit; return freq + (freqMultiplier - 1)*freqTonalityLimit;
return freqTonalityLimit*freqMultiplier + diff;
} }
return freq*freqMultiplier; return freq*freqMultiplier;
} }
@ -826,12 +826,21 @@ private:
} }
} }
// If we mapped formants the same way as mapFreq(), this would be the inverse
Sample invMapFormant(Sample freq) const {
if (freq*invFormantMultiplier > freqTonalityLimit) {
return freq + (1 - formantMultiplier)*freqTonalityLimit;
}
return freq*invFormantMultiplier;
}
Sample freqEstimateWeighted = 0; Sample freqEstimateWeighted = 0;
Sample freqEstimateWeight = 0; Sample freqEstimateWeight = 0;
std::vector<Sample> formantMetric; std::vector<Sample> formantMetric;
Sample formantBaseFreq = 0; Sample formantBaseFreq = 0;
void updateFormants(size_t) { void updateFormants(size_t) {
return;
for (auto &e : formantMetric) e = 0; for (auto &e : formantMetric) e = 0;
for (int c = 0; c < channels; ++c) { for (int c = 0; c < channels; ++c) {
Band *bins = bandsForChannel(c); Band *bins = bandsForChannel(c);
@ -883,7 +892,7 @@ private:
for (int b = 0; b < bands; ++b) { for (int b = 0; b < bands; ++b) {
formantMetric[b] = std::sqrt(std::sqrt(formantMetric[b])); formantMetric[b] = std::sqrt(std::sqrt(formantMetric[b]));
} }
Sample slew = 1/(freqEstimate*0.75 + 1); Sample slew = 1/(freqEstimate*0.71 + 1);
Sample e = 0; Sample e = 0;
for (int repeat = 0; repeat < 1; ++repeat) { for (int repeat = 0; repeat < 1; ++repeat) {
for (int b = bands - 1; b >= 0; --b) { for (int b = bands - 1; b >= 0; --b) {
@ -905,12 +914,10 @@ private:
return low + (high - low)*fracBand; return low + (high - low)*fracBand;
}; };
Sample formantMultiplierInv = 1/formantMultiplier;
for (int b = 0; b < bands; ++b) { for (int b = 0; b < bands; ++b) {
Sample inputF = bandToFreq(b); Sample inputF = bandToFreq(b);
Sample outputF = formantCompensation ? mapFreq(inputF) : inputF; Sample outputF = formantCompensation ? mapFreq(inputF) : inputF;
outputF *= formantMultiplierInv; outputF = invMapFormant(outputF);
Sample inputE = formantMetric[b]; Sample inputE = formantMetric[b];
Sample targetE = getFormant(freqToBand(outputF)); Sample targetE = getFormant(freqToBand(outputF));