Signalsmith-Audio/signalsmith-stretch
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De-emphasise phase-vocoder prediction when amplitude changes up or down

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Geraint 2022-12-18 17:07:16 +00:00
parent 7ca6c8d13c
commit fddcdb628f
1 changed files with 2 additions and 1 deletions
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signalsmith-stretch.h
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@ -360,6 +360,7 @@ private:
Sample fracIndex = mapPoint.inputBin - std::floor(mapPoint.inputBin);
Prediction &prediction = predictions[b];
Sample prevEnergy = prediction.energy;
prediction.energy = getFractional<&Band::inputEnergy>(c, lowIndex, fracIndex);
prediction.energy *= std::max<Sample>(0, mapPoint.freqGrad); // scale the energy according to local stretch factor
prediction.input = getFractional<&Band::input>(c, lowIndex, fracIndex);
@ -368,7 +369,7 @@ private:
Complex prevInput = getFractional<&Band::prevInput>(c, lowIndex, fracIndex);
Complex freqTwist = signalsmith::perf::mul<true>(prediction.input, prevInput);
Complex phase = signalsmith::perf::mul(outputBin.prevOutput, freqTwist);
outputBin.output = phase/(prediction.energy + noiseFloor);
outputBin.output = phase/(std::max(prevEnergy, prediction.energy) + noiseFloor);
if (b > 0) {
Complex downInput = getFractional<&Band::input>(c, mapPoint.inputBin - timeFactor);