Add new digital reverb model (#3277)

src/deluge/dsp/reverb/digital.hpp

@@ -0,0 +1,146 @@
+/*
+ * Copyright © 2024 Katherine Whitlock
+ *
+ * This file is part of The Synthstrom Audible Deluge Firmware.
+ *
+ * The Synthstrom Audible Deluge Firmware is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with this program.
+ * If not, see <https://www.gnu.org/licenses/>.
+ */
+#include "definitions_cxx.hpp"
+#include "mutable.hpp"
+
+namespace deluge::dsp::reverb {
+
+/// @brief The Griesinger topology model from Part 1 of Effect Design by John Dattorro,
+/// classically based on the famous Lexicon 224 Digital Reverb
+class Digital : public Mutable {
+	constexpr static float kRatio = 29761.f / kSampleRate; // Lexicon sample rate to Deluge sample rate
+
+	constexpr static size_t max_excursion = 16.f * kRatio;
+
+public:
+	void Process(std::span<q31_t> in, std::span<StereoSample> output) {
+		typename FxEngine::Context c;
+
+		typename FxEngine::AllPass ap1(142 * kRatio);
+		typename FxEngine::AllPass ap2(107 * kRatio);
+		typename FxEngine::AllPass ap3(379 * kRatio);
+		typename FxEngine::AllPass ap4(277 * kRatio);
+
+		typename FxEngine::AllPass dap1a((672 * kRatio) + max_excursion);
+		typename FxEngine::DelayLine del1a(4453 * kRatio);
+		typename FxEngine::AllPass dap1b(1800 * kRatio);
+		typename FxEngine::DelayLine del1b(3720 * kRatio);
+
+		typename FxEngine::AllPass dap2a((908 * kRatio) + max_excursion);
+		typename FxEngine::DelayLine del2a(4217 * kRatio);
+		typename FxEngine::AllPass dap2b(2656 * kRatio);
+		typename FxEngine::DelayLine del2b(3163 * kRatio);
+
+		FxEngine::ConstructTopology(engine_, {&ap1, &ap2, &ap3, &ap4,         //<
+		                                      &dap1a, &del1a, &dap1b, &del1b, //<
+		                                      &dap2a, &del2a, &dap2b, &del2b});
+
+		const float kdecay = reverb_time_;                          // 0.5f
+		const float kid1 = 0.750f;                                  // input diffusion 1
+		const float kid2 = 0.625f;                                  // input diffusion 2
+		const float kdd1 = 0.70f;                                   // decay diffusion 1
+		const float kdd2 = std::clamp(kdecay + 0.15f, 0.25f, 0.5f); // decay diffusion 2
+
+		const float kdamp = lp_; // 1.f - 0.0005f;            // damping
+		const float kbandwidth = 0.9995f;
+
+		const float gain = input_gain_;
+
+		float lp_1 = lp_decay_1_;
+		float lp_2 = lp_decay_2_;
+		float lp_band = lp_band_;
+
+		for (size_t frame = 0; frame < in.size(); ++frame) {
+			engine_.Advance();
+
+			const float input_sample = in[frame] / static_cast<float>(std::numeric_limits<int32_t>::max());
+			c.Set(input_sample); // * gain);
+
+			c.Lp(lp_band, kbandwidth);
+
+			// Diffuse through 4 allpasses.
+			ap1.Process(c, kid1);
+			ap2.Process(c, kid1);
+			ap3.Process(c, kid2);
+			ap4.Process(c, kid2);
+			float apout = c.Get();
+
+			// Main reverb loop.
+			c.Set(apout);
+			dap1a.Interpolate(c, 672.0f * kRatio, LFO_2, max_excursion, -kdd1);
+			del1a.Process(c);
+			c.Lp(lp_1, kdamp); // damping
+			c.Multiply(kdecay);
+			dap1b.Process(c, kdd2);
+			del1b.Process(c);
+			c.Multiply(kdecay);
+			c.Add(apout);
+			dap2a.Write(c, kdd2);
+
+			c.Set(apout);
+			dap2a.Interpolate(c, 908.0f * kRatio, LFO_1, max_excursion, -kdd1);
+			del2a.Process(c);
+			c.Lp(lp_1, kdamp); // damping
+			c.Multiply(kdecay);
+			dap2b.Process(c, kdd2);
+			del2b.Process(c);
+			c.Multiply(kdecay);
+			c.Add(apout);
+			dap1a.Write(c, kdd1);
+
+			float left_sum = 0;
+			left_sum += 0.6f * del2a.at(266 * kRatio);
+			left_sum += 0.6f * del2a.at(2974 * kRatio);
+			left_sum -= 0.6f * dap2b.at(1913 * kRatio);
+			left_sum += 0.6f * del2b.at(1996 * kRatio);
+			left_sum -= 0.6f * del1a.at(1990 * kRatio);
+			left_sum -= 0.6f * dap1b.at(187 * kRatio);
+			left_sum -= 0.6f * del1b.at(1066 * kRatio);
+			left_sum = left_sum - dsp::OnePole(hp_l_, left_sum, hp_cutoff_);
+			left_sum = dsp::OnePole(lp_l_, left_sum, lp_cutoff_);
+
+			float right_sum = 0;
+			right_sum += 0.6f * del1a.at(353 * kRatio);
+			right_sum += 0.6f * del1a.at(3627 * kRatio);
+			right_sum -= 0.6f * dap1b.at(1228 * kRatio);
+			right_sum += 0.6f * del1b.at(2673 * kRatio);
+			right_sum -= 0.6f * del2a.at(2111 * kRatio);
+			right_sum -= 0.6f * dap2b.at(335 * kRatio);
+			right_sum -= 0.6f * del2b.at(121 * kRatio);
+			right_sum = right_sum - dsp::OnePole(hp_l_, right_sum, hp_cutoff_);
+			right_sum = dsp::OnePole(lp_l_, right_sum, lp_cutoff_);
+
+			q31_t output_left =
+			    static_cast<int32_t>(left_sum * static_cast<float>(std::numeric_limits<uint32_t>::max()) * 0xF);
+
+			q31_t output_right =
+			    static_cast<int32_t>(left_sum * static_cast<float>(std::numeric_limits<uint32_t>::max()) * 0xF);
+
+			// Mix
+			output[frame].l += multiply_32x32_rshift32_rounded(output_left, getPanLeft());
+			output[frame].r += multiply_32x32_rshift32_rounded(output_right, getPanRight());
+		}
+
+		lp_decay_1_ = lp_1;
+		lp_decay_2_ = lp_2;
+		lp_band_ = lp_band;
+	}
+
+private:
+	float lp_band_;
+};
+} // namespace deluge::dsp::reverb

src/deluge/dsp/reverb/mutable/reverb.hpp → src/deluge/dsp/reverb/mutable.hpp

@@ -84,10 +84,9 @@ class Mutable : public Base {
 			dap1b.Process(c, kap);
 			del1.Write(c, 2.0f);
 			wet = c.Get();
-			dsp::OnePole(hp_r_, wet, hp_cutoff_);
-			wet = wet - hp_r_;
-			dsp::OnePole(lp_r_, wet, lp_cutoff_);
-			wet = lp_r_;
+			wet = wet - dsp::OnePole(hp_r_, wet, hp_cutoff_);
+			;
+			wet = dsp::OnePole(lp_r_, wet, lp_cutoff_);
 
 			auto output_right =
 			    static_cast<int32_t>(wet * static_cast<float>(std::numeric_limits<uint32_t>::max()) * 0xF);
@@ -99,10 +98,10 @@ class Mutable : public Base {
 			dap2b.Process(c, kap);
 			del2.Write(c, 2.0f);
 			wet = c.Get();
-			dsp::OnePole(hp_l_, wet, hp_cutoff_);
-			wet = wet - hp_l_;
-			dsp::OnePole(lp_l_, wet, lp_cutoff_);
-			wet = lp_l_;
+			wet = wet - dsp::OnePole(hp_l_, wet, hp_cutoff_);
+			;
+			wet = dsp::OnePole(lp_l_, wet, lp_cutoff_);
+			;
 
 			auto output_left =
 			    static_cast<int32_t>(wet * static_cast<float>(std::numeric_limits<uint32_t>::max()) * 0xF);
@@ -154,7 +153,7 @@ class Mutable : public Base {
 
 	[[nodiscard]] float getLPF() const override { return lp_cutoff_val_; }
 
-private:
+protected:
 	static constexpr float sample_rate = kSampleRate;
 
 	std::array<float, kBufferSize> buffer_{};

src/deluge/dsp/reverb/reverb.hpp

@@ -1,7 +1,9 @@
 #pragma once
 #include "base.hpp"
+#include "deluge/dsp/reverb/reverb.hpp"
+#include "digital.hpp"
 #include "freeverb/freeverb.hpp"
-#include "mutable/reverb.hpp"
+#include "mutable.hpp"
 #include <algorithm>
 #include <cstdint>
 #include <variant>
@@ -13,6 +15,7 @@ class [[gnu::hot]] Reverb : reverb::Base {
 	enum class Model {
 		FREEVERB = 0, // Freeverb is the original
 		MUTABLE,
+		DIGITAL,
 	};
 
 	Reverb()
@@ -28,6 +31,9 @@ class [[gnu::hot]] Reverb : reverb::Base {
 		case Model::FREEVERB:
 			reverb_.emplace<reverb::Freeverb>();
 			break;
+		case Model::DIGITAL:
+			reverb_.emplace<reverb::Digital>();
+			break;
 		case Model::MUTABLE:
 			reverb_.emplace<reverb::Mutable>();
 			break;
@@ -51,6 +57,9 @@ class [[gnu::hot]] Reverb : reverb::Base {
 		case Model::MUTABLE:
 			reverb_as<Mutable>().process(input, output);
 			break;
+		case Model::DIGITAL:
+			reverb_as<Digital>().process(input, output);
+			break;
 		}
 	}
 
@@ -99,7 +108,8 @@ class [[gnu::hot]] Reverb : reverb::Base {
 private:
 	std::variant<         //<
 	    reverb::Freeverb, //<
-	    reverb::Mutable   //<
+	    reverb::Mutable,  //<
+	    reverb::Digital   //<
 	    >
 	    reverb_{};
 

src/deluge/gui/menu_item/reverb/hpf.h

@@ -16,7 +16,7 @@
  */
 #pragma once
 #include "definitions_cxx.hpp"
-#include "dsp/reverb/mutable/reverb.hpp"
+#include "dsp/reverb/mutable.hpp"
 #include "dsp/reverb/reverb.hpp"
 #include "gui/l10n/strings.h"
 #include "gui/menu_item/integer.h"
@@ -33,7 +33,8 @@ class HPF final : public Integer {
 	[[nodiscard]] int32_t getMaxValue() const override { return kMaxMenuValue; }
 
 	bool isRelevant(ModControllableAudio* modControllable, int32_t whichThing) override {
-		return (AudioEngine::reverb.getModel() == dsp::Reverb::Model::MUTABLE);
+		auto model = AudioEngine::reverb.getModel();
+		return (model == dsp::Reverb::Model::MUTABLE) || (model == dsp::Reverb::Model::DIGITAL);
 	}
 };
 } // namespace deluge::gui::menu_item::reverb

src/deluge/gui/menu_item/reverb/lpf.h

@@ -16,7 +16,6 @@
  */
 #pragma once
 #include "definitions_cxx.hpp"
-#include "dsp/reverb/mutable/reverb.hpp"
 #include "dsp/reverb/reverb.hpp"
 #include "gui/l10n/strings.h"
 #include "gui/menu_item/integer.h"
@@ -33,7 +32,8 @@ class LPF final : public Integer {
 	[[nodiscard]] int32_t getMaxValue() const override { return kMaxMenuValue; }
 
 	bool isRelevant(ModControllableAudio* modControllable, int32_t whichThing) override {
-		return (AudioEngine::reverb.getModel() == dsp::Reverb::Model::MUTABLE);
+		auto model = AudioEngine::reverb.getModel();
+		return (model == dsp::Reverb::Model::MUTABLE) || (model == dsp::Reverb::Model::DIGITAL);
 	}
 };
 } // namespace deluge::gui::menu_item::reverb

src/deluge/gui/menu_item/reverb/model.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "dsp/reverb/reverb.hpp"
+#include "gui/l10n/l10n.h"
 #include "gui/menu_item/selection.h"
 #include "processing/engines/audio_engine.h"
 #include <string_view>
@@ -16,10 +17,8 @@ class Model final : public Selection {
 
 	deluge::vector<std::string_view> getOptions(OptType optType) override {
 		using enum l10n::String;
-		return {
-		    l10n::getView(STRING_FOR_FREEVERB),
-		    l10n::getView(STRING_FOR_MUTABLE),
-		};
+		return {l10n::getView(STRING_FOR_FREEVERB), l10n::getView(STRING_FOR_MUTABLE),
+		        l10n::getView(STRING_FOR_DIGITAL)};
 	}
 };
 } // namespace deluge::gui::menu_item::reverb

src/deluge/gui/menu_item/reverb/room_size.h

@@ -32,6 +32,7 @@ class RoomSize final : public Integer {
 	[[nodiscard]] std::string_view getName() const override {
 		using enum l10n::String;
 		switch (AudioEngine::reverb.getModel()) {
+		case dsp::Reverb::Model::DIGITAL:
 		case dsp::Reverb::Model::MUTABLE:
 			return l10n::getView(STRING_FOR_TIME);
 		default:

src/deluge/gui/menu_item/reverb/width.h

@@ -32,6 +32,7 @@ class Width final : public Integer {
 	[[nodiscard]] std::string_view getName() const override {
 		using enum l10n::String;
 		switch (AudioEngine::reverb.getModel()) {
+		case dsp::Reverb::Model::DIGITAL:
 		case dsp::Reverb::Model::MUTABLE:
 			return l10n::getView(STRING_FOR_DIFFUSION);
 		default: