259 lines
9.4 KiB
C++
259 lines
9.4 KiB
C++
/**
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* OpenAL cross platform audio library
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* Copyright (C) 2018 by Raul Herraiz.
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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* Or go to http://www.gnu.org/copyleft/lgpl.html
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*/
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#include "config.h"
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#include <cmath>
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#include <cstdlib>
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#include <array>
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#include <complex>
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#include <algorithm>
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#include "al/auxeffectslot.h"
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#include "alcmain.h"
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#include "alcomplex.h"
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#include "alcontext.h"
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#include "alnumeric.h"
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#include "alu.h"
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namespace {
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using complex_d = std::complex<double>;
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#define STFT_SIZE 1024
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#define STFT_HALF_SIZE (STFT_SIZE>>1)
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#define OVERSAMP (1<<2)
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#define STFT_STEP (STFT_SIZE / OVERSAMP)
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#define FIFO_LATENCY (STFT_STEP * (OVERSAMP-1))
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/* Define a Hann window, used to filter the STFT input and output. */
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std::array<double,STFT_SIZE> InitHannWindow()
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{
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std::array<double,STFT_SIZE> ret;
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/* Create lookup table of the Hann window for the desired size, i.e. STFT_SIZE */
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for(size_t i{0};i < STFT_SIZE>>1;i++)
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{
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constexpr double scale{al::MathDefs<double>::Pi() / double{STFT_SIZE}};
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const double val{std::sin(static_cast<double>(i+1) * scale)};
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ret[i] = ret[STFT_SIZE-1-i] = val * val;
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}
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return ret;
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}
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alignas(16) const std::array<double,STFT_SIZE> HannWindow = InitHannWindow();
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struct FrequencyBin {
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double Amplitude;
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double FreqBin;
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};
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struct PshifterState final : public EffectState {
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/* Effect parameters */
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size_t mCount;
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ALuint mPitchShiftI;
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double mPitchShift;
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/* Effects buffers */
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std::array<double,STFT_SIZE> mFIFO;
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std::array<double,STFT_HALF_SIZE+1> mLastPhase;
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std::array<double,STFT_HALF_SIZE+1> mSumPhase;
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std::array<double,STFT_SIZE> mOutputAccum;
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std::array<complex_d,STFT_SIZE> mFftBuffer;
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std::array<FrequencyBin,STFT_HALF_SIZE+1> mAnalysisBuffer;
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std::array<FrequencyBin,STFT_HALF_SIZE+1> mSynthesisBuffer;
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alignas(16) FloatBufferLine mBufferOut;
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/* Effect gains for each output channel */
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float mCurrentGains[MAX_OUTPUT_CHANNELS];
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float mTargetGains[MAX_OUTPUT_CHANNELS];
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void deviceUpdate(const ALCdevice *device) override;
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void update(const ALCcontext *context, const EffectSlot *slot, const EffectProps *props,
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const EffectTarget target) override;
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void process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn,
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const al::span<FloatBufferLine> samplesOut) override;
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DEF_NEWDEL(PshifterState)
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};
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void PshifterState::deviceUpdate(const ALCdevice* /*device*/)
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{
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/* (Re-)initializing parameters and clear the buffers. */
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mCount = FIFO_LATENCY;
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mPitchShiftI = MixerFracOne;
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mPitchShift = 1.0;
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std::fill(mFIFO.begin(), mFIFO.end(), 0.0);
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std::fill(mLastPhase.begin(), mLastPhase.end(), 0.0);
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std::fill(mSumPhase.begin(), mSumPhase.end(), 0.0);
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std::fill(mOutputAccum.begin(), mOutputAccum.end(), 0.0);
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std::fill(mFftBuffer.begin(), mFftBuffer.end(), complex_d{});
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std::fill(mAnalysisBuffer.begin(), mAnalysisBuffer.end(), FrequencyBin{});
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std::fill(mSynthesisBuffer.begin(), mSynthesisBuffer.end(), FrequencyBin{});
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std::fill(std::begin(mCurrentGains), std::end(mCurrentGains), 0.0f);
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std::fill(std::begin(mTargetGains), std::end(mTargetGains), 0.0f);
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}
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void PshifterState::update(const ALCcontext*, const EffectSlot *slot,
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const EffectProps *props, const EffectTarget target)
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{
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const int tune{props->Pshifter.CoarseTune*100 + props->Pshifter.FineTune};
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const float pitch{std::pow(2.0f, static_cast<float>(tune) / 1200.0f)};
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mPitchShiftI = fastf2u(pitch*MixerFracOne);
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mPitchShift = mPitchShiftI * double{1.0/MixerFracOne};
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const auto coeffs = CalcDirectionCoeffs({0.0f, 0.0f, -1.0f}, 0.0f);
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mOutTarget = target.Main->Buffer;
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ComputePanGains(target.Main, coeffs.data(), slot->Gain, mTargetGains);
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}
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void PshifterState::process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut)
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{
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/* Pitch shifter engine based on the work of Stephan Bernsee.
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* http://blogs.zynaptiq.com/bernsee/pitch-shifting-using-the-ft/
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*/
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/* Cycle offset per update expected of each frequency bin (bin 0 is none,
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* bin 1 is x1, bin 2 is x2, etc).
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*/
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constexpr double expected_cycles{al::MathDefs<double>::Tau() / OVERSAMP};
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for(size_t base{0u};base < samplesToDo;)
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{
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const size_t todo{minz(STFT_SIZE-mCount, samplesToDo-base)};
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/* Retrieve the output samples from the FIFO and fill in the new input
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* samples.
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*/
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auto fifo_iter = mFIFO.begin() + mCount;
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std::transform(fifo_iter, fifo_iter+todo, mBufferOut.begin()+base,
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[](double d) noexcept -> float { return static_cast<float>(d); });
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std::copy_n(samplesIn[0].begin()+base, todo, fifo_iter);
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mCount += todo;
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base += todo;
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/* Check whether FIFO buffer is filled with new samples. */
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if(mCount < STFT_SIZE) break;
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mCount = FIFO_LATENCY;
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/* Time-domain signal windowing, store in FftBuffer, and apply a
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* forward FFT to get the frequency-domain signal.
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*/
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for(size_t k{0u};k < STFT_SIZE;k++)
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mFftBuffer[k] = mFIFO[k] * HannWindow[k];
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forward_fft(mFftBuffer);
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/* Analyze the obtained data. Since the real FFT is symmetric, only
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* STFT_HALF_SIZE+1 samples are needed.
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*/
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for(size_t k{0u};k < STFT_HALF_SIZE+1;k++)
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{
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const double amplitude{std::abs(mFftBuffer[k])};
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const double phase{std::arg(mFftBuffer[k])};
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/* Compute phase difference and subtract expected phase difference */
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double tmp{(phase - mLastPhase[k]) - static_cast<double>(k)*expected_cycles};
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/* Map delta phase into +/- Pi interval */
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int qpd{double2int(tmp / al::MathDefs<double>::Pi())};
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tmp -= al::MathDefs<double>::Pi() * (qpd + (qpd%2));
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/* Get deviation from bin frequency from the +/- Pi interval */
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tmp /= expected_cycles;
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/* Compute the k-th partials' true frequency and store the
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* amplitude and frequency bin in the analysis buffer.
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*/
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mAnalysisBuffer[k].Amplitude = amplitude;
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mAnalysisBuffer[k].FreqBin = static_cast<double>(k) + tmp;
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/* Store the actual phase[k] for the next frame. */
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mLastPhase[k] = phase;
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}
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/* Shift the frequency bins according to the pitch adjustment,
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* accumulating the amplitudes of overlapping frequency bins.
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*/
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std::fill(mSynthesisBuffer.begin(), mSynthesisBuffer.end(), FrequencyBin{});
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const size_t bin_count{minz(STFT_HALF_SIZE+1,
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(((STFT_HALF_SIZE+1)<<MixerFracBits) - (MixerFracOne>>1) - 1)/mPitchShiftI + 1)};
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for(size_t k{0u};k < bin_count;k++)
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{
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const size_t j{(k*mPitchShiftI + (MixerFracOne>>1)) >> MixerFracBits};
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mSynthesisBuffer[j].Amplitude += mAnalysisBuffer[k].Amplitude;
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mSynthesisBuffer[j].FreqBin = mAnalysisBuffer[k].FreqBin * mPitchShift;
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}
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/* Reconstruct the frequency-domain signal from the adjusted frequency
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* bins.
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*/
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for(size_t k{0u};k < STFT_HALF_SIZE+1;k++)
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{
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/* Calculate actual delta phase and accumulate it to get bin phase */
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mSumPhase[k] += mSynthesisBuffer[k].FreqBin * expected_cycles;
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mFftBuffer[k] = std::polar(mSynthesisBuffer[k].Amplitude, mSumPhase[k]);
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}
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for(size_t k{STFT_HALF_SIZE+1};k < STFT_SIZE;++k)
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mFftBuffer[k] = std::conj(mFftBuffer[STFT_SIZE-k]);
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/* Apply an inverse FFT to get the time-domain siganl, and accumulate
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* for the output with windowing.
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*/
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inverse_fft(mFftBuffer);
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for(size_t k{0u};k < STFT_SIZE;k++)
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mOutputAccum[k] += HannWindow[k]*mFftBuffer[k].real() * (4.0/OVERSAMP/STFT_SIZE);
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/* Shift FIFO and accumulator. */
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fifo_iter = std::copy(mFIFO.begin()+STFT_STEP, mFIFO.end(), mFIFO.begin());
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std::copy_n(mOutputAccum.begin(), STFT_STEP, fifo_iter);
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auto accum_iter = std::copy(mOutputAccum.begin()+STFT_STEP, mOutputAccum.end(),
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mOutputAccum.begin());
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std::fill(accum_iter, mOutputAccum.end(), 0.0);
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}
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/* Now, mix the processed sound data to the output. */
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MixSamples({mBufferOut.data(), samplesToDo}, samplesOut, mCurrentGains, mTargetGains,
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maxz(samplesToDo, 512), 0);
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}
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struct PshifterStateFactory final : public EffectStateFactory {
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EffectState *create() override { return new PshifterState{}; }
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};
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} // namespace
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EffectStateFactory *PshifterStateFactory_getFactory()
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{
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static PshifterStateFactory PshifterFactory{};
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return &PshifterFactory;
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}
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