290 lines
8.9 KiB
C++
290 lines
8.9 KiB
C++
/* Copyright 2022 Signalsmith Audio Ltd. / Geraint Luff
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Released under the Boost Software License (see LICENSE.txt) */
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#ifndef SIGNALSMITH_BASICS_REVERB_H
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#define SIGNALSMITH_BASICS_REVERB_H
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#include "dsp/delay.h"
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#include "dsp/mix.h"
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SIGNALSMITH_DSP_VERSION_CHECK(1, 3, 3)
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#include "./stfx-library.h"
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#include "./units.h"
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#include <cmath>
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#include <random>
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namespace signalsmith { namespace basics {
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template<typename Sample, class BaseEffect>
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struct ReverbSTFX : public BaseEffect {
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using typename BaseEffect::ParamRange;
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using typename BaseEffect::ParamSteps;
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using Array = std::array<Sample, 8>;
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ParamRange dry{1}, wet{0.25};
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ParamRange roomMs{100};
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ParamRange rt20{3};
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ParamRange early{1};
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ReverbSTFX(double maxRoomMs=200) : maxRoomMs(maxRoomMs) {}
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template<class Storage>
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void state(Storage &storage) {
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using namespace signalsmith::units;
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storage.info("[Basics] Reverb", "An FDN reverb");
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int version = storage.version(3);
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if (version != 3) return;
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storage.param("dry", dry)
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.info("dry", "dry signal gain")
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.range(0, 1, 4)
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.unit("dB", 1, dbToGain, gainToDb)
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.unit("%", 0, pcToRatio, ratioToPc)
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.exact(0, "off")
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.unit("");
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storage.param("wet", wet)
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.info("wet", "reverb tail gain")
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.range(0, 1, 4)
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.unit("dB", 1, dbToGain, gainToDb)
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.unit("%", 0, pcToRatio, ratioToPc)
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.exact(0, "off")
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.unit("");
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storage.param("roomMs", roomMs)
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.info("room", "room size (1ms ~ 1 foot)")
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.range(10, 100, maxRoomMs)
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.unit("ms", 0);
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storage.param("rt20", rt20)
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.info("decay", "RT20: decay time to -20dB")
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.range(0.1, 3, 30)
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.unit("seconds", 2, 0, 1)
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.unit("seconds", 1, 1, 1e100);
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storage.param("early", early)
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.info("early", "Early reflections")
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.range(0, 1, 2)
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.unit("%", 0, pcToRatio, ratioToPc);
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}
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template<class Config>
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void configure(Config &config) {
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config.outputChannels = config.inputChannels = 2;
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config.auxInputs.resize(0);
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config.auxOutputs.resize(0);
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double maxRoomSamples = maxRoomMs*0.001*config.sampleRate;
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delay1.configure(maxRoomSamples, 0.125);
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delay2.configure(maxRoomSamples, 1);
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delay3.configure(maxRoomSamples, 0.5);
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delay4.configure(maxRoomSamples, 0.25);
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delayFeedback.configure(maxRoomSamples*2, 1);
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delayEarly.configure(maxRoomSamples, 0.25);
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}
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void reset() {
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delay1.reset();
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delay2.reset();
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delay3.reset();
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delayFeedback.reset();
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delayEarly.reset();
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}
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int latencySamples() const {
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return 0;
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}
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template<class Io, class Config, class Block>
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void processSTFX(Io &io, Config &config, Block &block) {
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using Hadamard = signalsmith::mix::Hadamard<Sample, 8>;
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using Householder = signalsmith::mix::Householder<Sample, 8>;
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auto &&inputLeft = io.input[0];
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auto &&inputRight = io.input[1];
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auto &&outputLeft = io.output[0];
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auto &&outputRight = io.output[1];
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auto smoothedDryGain = block.smooth(dry);
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Sample scalingFactor = stereoMixer.scalingFactor2()*0.015625; // 4 Hadamard mixes
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auto smoothedWetGain = block.smooth(wet.from(), wet.to());
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auto smoothedInputGain = block.smooth( // tuned by ear: smaller feedback loops with longer decays sound louder
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scalingFactor*std::sqrt(roomMs.from()/(rt20.from()*50 + roomMs.from())),
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scalingFactor*std::sqrt(roomMs.to()/(rt20.to()*50 + roomMs.to()))
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);
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using signalsmith::units::dbToGain;
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auto smoothedDecayGain = block.smooth(
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dbToGain(getDecayDb(rt20.from(), roomMs.from())),
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dbToGain(getDecayDb(rt20.to(), roomMs.to()))
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);
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auto smoothedEarlyGain = block.smooth(early, [&](double g) {
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return g*0.35; // tuned by ear
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});
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block.setupFade([&](){
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updateDelays(roomMs.to()*0.001*config.sampleRate);
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});
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bool fading = block.fading();
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for (int i = 0; i < block.length; ++i) {
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Sample inputGain = smoothedInputGain.at(i);
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Sample decayGain = smoothedDecayGain.at(i);
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Sample earlyGain = smoothedEarlyGain.at(i);
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Array samples;
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std::array<Sample, 2> stereoIn = {inputLeft[i]*inputGain, inputRight[i]*inputGain};
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stereoMixer.stereoToMulti(stereoIn, samples);
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if (fading) {
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Sample fade = block.fade(i);
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samples = delay1.write(samples).read(fade);
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Hadamard::unscaledInPlace(samples);
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samples = delay2.write(samples).read(fade);
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Hadamard::unscaledInPlace(samples);
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Array feedback = delayFeedback.read(fade);
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Householder::inPlace(feedback);
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Array feedbackInput;
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for (int c = 0; c < 8; ++c) feedbackInput[c] = samples[c] + feedback[c]*decayGain;
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delayFeedback.write(feedbackInput);
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Array earlyReflections = delayEarly.write(samples).read(fade);
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Hadamard::unscaledInPlace(earlyReflections);
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for (int c = 0; c < 8; ++c) samples[c] = feedback[c] + earlyReflections[c]*earlyGain;
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samples = delay3.write(samples).read(fade);
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Hadamard::unscaledInPlace(samples);
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samples = delay4.write(samples).read(fade);
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} else {
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samples = delay1.write(samples).read();
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Hadamard::unscaledInPlace(samples);
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samples = delay2.write(samples).read();
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Hadamard::unscaledInPlace(samples);
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Array feedback = delayFeedback.read();
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Householder::inPlace(feedback);
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Array feedbackInput;
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for (int c = 0; c < 8; ++c) feedbackInput[c] = samples[c] + feedback[c]*decayGain;
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delayFeedback.write(feedbackInput);
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Array earlyReflections = delayEarly.write(samples).read();
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Hadamard::unscaledInPlace(earlyReflections);
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for (int c = 0; c < 8; ++c) samples[c] = feedback[c] + earlyReflections[c]*earlyGain;
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samples = delay3.write(samples).read();
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Hadamard::unscaledInPlace(samples);
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samples = delay4.write(samples).read();
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}
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std::array<Sample, 2> stereoOut;
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stereoMixer.multiToStereo(samples, stereoOut);
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Sample dryGain = smoothedDryGain.at(i);
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Sample wetGain = smoothedWetGain.at(i);
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outputLeft[i] = stereoIn[0]*dryGain + stereoOut[0]*wetGain;
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outputRight[i] = stereoIn[1]*dryGain + stereoOut[1]*wetGain;
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}
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}
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private:
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int channels = 0;
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double maxRoomMs;
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static Sample getDecayDb(Sample rt20, Sample loopMs) {
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Sample dbPerSecond = -20/rt20;
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Sample secondsPerLoop = loopMs*Sample(0.001);
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return dbPerSecond*secondsPerLoop;
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}
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signalsmith::mix::StereoMultiMixer<Sample, 8> stereoMixer;
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struct MultiDelay {
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signalsmith::delay::MultiBuffer<Sample> buffer;
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double delayScale = 1;
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std::array<int, 8> delayOffsets, delayOffsetsPrev;
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void configure(double maxRangeSamples, double scale) {
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delayScale = scale;
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buffer.resize(8, std::ceil(maxRangeSamples*delayScale) + 1);
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}
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void reset() {
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buffer.reset();
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}
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void updateLengths(int seed, double rangeSamples, bool minimise=true) {
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rangeSamples *= delayScale;
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delayOffsetsPrev = delayOffsets;
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std::mt19937 engine(seed);
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std::uniform_real_distribution<float> unitDist(0, 1);
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for (int i = 0; i < 8; ++i) {
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float unit = unitDist(engine);
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delayOffsets[i] = int(-std::floor(rangeSamples*(unit + i)/8));
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std::uniform_int_distribution<int> indexDist(0, i);
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int swapIndex = indexDist(engine);
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std::swap(delayOffsets[i], delayOffsets[swapIndex]);
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}
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if (minimise) { // Moves things along so the shortest delay is always 0
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int maximumDelay = delayOffsets[0];
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for (auto &d : delayOffsets) maximumDelay = std::max(d, maximumDelay);
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for (auto &d : delayOffsets) d -= maximumDelay;
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}
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}
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void updateLengthsExponential(int seed, double rangeSamples) {
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rangeSamples *= delayScale;
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delayOffsetsPrev = delayOffsets;
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std::mt19937 engine(seed);
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constexpr double ratios[8] = {0.125, -0.125, 0.375, -0.375, 0.625, -0.625, 0.875, -0.875};
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for (int i = 0; i < 8; ++i) {
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delayOffsets[i] = int(-std::floor(rangeSamples*std::pow(2, ratios[i]/2)));
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std::uniform_int_distribution<int> indexDist(0, i);
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int swapIndex = indexDist(engine);
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std::swap(delayOffsets[i], delayOffsets[swapIndex]);
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}
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}
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MultiDelay & write(const Array &arr) {
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++buffer;
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for (int i = 0; i < 8; ++i) {
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buffer[i][0] = arr[i];
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}
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return *this;
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}
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Array read() {
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Array result;
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for (int i = 0; i < 8; ++i) {
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result[i] = buffer[i][delayOffsets[i]];
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}
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return result;
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}
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Array read(Sample fade) {
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Array result;
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for (int i = 0; i < 8; ++i) {
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Sample to = buffer[i][delayOffsets[i]];
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Sample from = buffer[i][delayOffsetsPrev[i]];
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result[i] = from + (to - from)*fade;
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}
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return result;
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}
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};
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MultiDelay delay1, delay2, delay3, delay4, delayFeedback, delayEarly;
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void updateDelays(double roomSamples) {
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delay1.updateLengths(0x876753A5, roomSamples, false);
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delay2.updateLengths(0x876753A5, roomSamples);
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delay3.updateLengths(0x5974DF44, roomSamples);
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delay4.updateLengths(0x8CDBF7E6, roomSamples);
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delayFeedback.updateLengthsExponential(0xC6BF7158, roomSamples);
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delayEarly.updateLengths(0x0BDDE171, roomSamples);
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}
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};
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using Reverb = stfx::LibraryEffect<float, ReverbSTFX>;
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}} // namespace
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#endif // include guard
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