Signalsmith-Audio/signalsmith-stretch
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Calculate interval-step twists on-the-fly

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Geraint 2025-01-07 18:37:22 +00:00
parent 6eac082ad2
commit bc8a7fd65e
1 changed files with 8 additions and 12 deletions
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20
signalsmith-stretch.h
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@ -59,9 +59,6 @@ struct SignalsmithStretch {
timeBuffer.assign(stft.fftSize(), 0); timeBuffer.assign(stft.fftSize(), 0);
channelBands.assign(bands*channels, Band()); channelBands.assign(bands*channels, Band());
// Various phase rotations
rotPrevInterval.assign(bands, 0);
timeShiftPhases(-intervalSamples, rotPrevInterval);
peaks.reserve(bands/2); peaks.reserve(bands/2);
energy.resize(bands); energy.resize(bands);
smoothedEnergy.resize(bands); smoothedEnergy.resize(bands);
@ -307,19 +304,12 @@ private:
bool didSeek = false, flushed = true; bool didSeek = false, flushed = true;
Sample seekTimeFactor = 1; Sample seekTimeFactor = 1;
std::vector<Complex> rotPrevInterval;
Sample bandToFreq(Sample b) const { Sample bandToFreq(Sample b) const {
return (b + Sample(0.5))/stft.fftSize(); return (b + Sample(0.5))/stft.fftSize();
} }
Sample freqToBand(Sample f) const { Sample freqToBand(Sample f) const {
return f*stft.fftSize() - Sample(0.5); return f*stft.fftSize() - Sample(0.5);
} }
void timeShiftPhases(Sample shiftSamples, std::vector<Complex> &output) const {
for (int b = 0; b < bands; ++b) {
Sample phase = bandToFreq(b)*shiftSamples*Sample(-2*M_PI);
output[b] = {std::cos(phase), std::sin(phase)};
}
}
struct Band { struct Band {
Complex input, prevInput{0}; Complex input, prevInput{0};
@ -403,10 +393,16 @@ private:
if (newSpectrum) { if (newSpectrum) {
for (int c = 0; c < channels; ++c) { for (int c = 0; c < channels; ++c) {
auto bins = bandsForChannel(c); auto bins = bandsForChannel(c);
Complex rot = std::polar(Sample(1), bandToFreq(0)*stft.interval()*Sample(2*M_PI));
Sample freqStep = bandToFreq(1) - bandToFreq(0);
Complex rotStep = std::polar(Sample(1), freqStep*stft.interval()*Sample(2*M_PI));
for (int b = 0; b < bands; ++b) { for (int b = 0; b < bands; ++b) {
auto &bin = bins[b]; auto &bin = bins[b];
bin.output = signalsmith::perf::mul(bin.output, rotPrevInterval[b]); bin.output = signalsmith::perf::mul(bin.output, rot);
bin.prevInput = signalsmith::perf::mul(bin.prevInput, rotPrevInterval[b]); bin.prevInput = signalsmith::perf::mul(bin.prevInput, rot);
rot = signalsmith::perf::mul(rot, rotStep);
} }
} }
} }