Initial effects

src/CMakeLists.txt

@@ -15,6 +15,9 @@ set (SFIZZ_SOURCES
     sfizz/FloatEnvelopes.cpp
     sfizz/Logger.cpp
     sfizz/SfzFilter.cpp
+    sfizz/Effects.cpp
+    sfizz/effects/Nothing.cpp
+    sfizz/effects/Lofi.cpp
 )
 include (SfizzSIMDSourceFiles)
 

src/sfizz/AudioSpan.h

@@ -209,6 +209,22 @@ class AudioSpan {
         return {};
     }
 
+    /**
+     * @brief Convert implicitly to a pointer of channels
+     */
+    operator const float* const *() const noexcept
+    {
+        return spans.data();
+    }
+
+    /**
+     * @brief Convert implicitly to a pointer of channels
+     */
+    operator float* const *() noexcept
+    {
+        return spans.data();
+    }
+
     /**
      * @brief Get a Span<Type> corresponding to a specific channel
      *

src/sfizz/Config.h

@@ -69,6 +69,10 @@ namespace config {
      */
     const absl::string_view midnamManufacturer { "The Sfizz authors" };
     const absl::string_view midnamModel { "Sfizz" };
+    /**
+       Limit of how many "fxN" buses are accepted (in SFZv2, maximum is 4)
+     */
+    constexpr int maxEffectBuses { 256 };
 } // namespace config
 
 // Enable or disable SIMD accelerators by default

src/sfizz/Effects.cpp

@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#include "Effects.h"
+#include "AudioSpan.h"
+#include "Opcode.h"
+#include "SIMDHelpers.h"
+#include "Config.h"
+#include "effects/Nothing.h"
+#include "effects/Lofi.h"
+#include <algorithm>
+
+namespace sfz {
+
+void EffectFactory::registerStandardEffectTypes()
+{
+    // TODO
+    registerEffectType("lofi", fx::Lofi::makeInstance);
+}
+
+void EffectFactory::registerEffectType(absl::string_view name, Effect::MakeInstance& make)
+{
+    FactoryEntry ent;
+    ent.name = std::string(name);
+    ent.make = &make;
+    _entries.push_back(std::move(ent));
+}
+
+Effect* EffectFactory::makeEffect(absl::Span<const Opcode> members)
+{
+    const Opcode* opcode = nullptr;
+
+    for (auto it = members.rbegin(); it != members.rend() && !opcode; ++it) {
+        if (it->lettersOnlyHash == hash("type"))
+            opcode = &*it;
+    }
+
+    if (!opcode) {
+        DBG("The effect does not specify a type");
+        return new sfz::fx::Nothing;
+    }
+
+    absl::string_view type = opcode->value;
+
+    auto it = _entries.begin();
+    auto end = _entries.end();
+    for (; it != end && it->name != type; ++it)
+        ;
+
+    if (it == end) {
+        DBG("Unsupported effect type: " << type);
+        return new sfz::fx::Nothing;
+    }
+
+    Effect* fx = it->make(members);
+    if (!fx) {
+        DBG("Could not instantiate effect of type: " << type);
+        return new sfz::fx::Nothing;
+    }
+
+    return fx;
+}
+
+///
+EffectBus::EffectBus()
+{
+}
+
+EffectBus::~EffectBus()
+{
+}
+
+void EffectBus::addEffect(std::unique_ptr<Effect> fx)
+{
+    _effects.emplace_back(std::move(fx));
+}
+
+void EffectBus::clearInputs(unsigned nframes)
+{
+    AudioSpan<float>(_inputs).first(nframes).fill(0.0f);
+    AudioSpan<float>(_outputs).first(nframes).fill(0.0f);
+}
+
+void EffectBus::addToInputs(const float* const addInput[], float addGain, unsigned nframes)
+{
+    if (addGain == 0)
+        return;
+
+    for (unsigned c = 0; c < EffectChannels; ++c) {
+        absl::Span<const float> addIn(addInput[c], nframes);
+        sfz::multiplyAdd(addGain, addIn, _inputs.getSpan(c));
+    }
+}
+
+void EffectBus::init(double sampleRate)
+{
+    for (const auto& effectPtr : _effects)
+        effectPtr->init(sampleRate);
+}
+
+void EffectBus::clear()
+{
+    for (const auto& effectPtr : _effects)
+        effectPtr->clear();
+}
+
+void EffectBus::process(unsigned nframes)
+{
+    size_t numEffects = _effects.size();
+
+    if (numEffects > 0 && hasNonZeroOutput()) {
+        _effects[0]->process(
+            AudioSpan<float>(_inputs), AudioSpan<float>(_outputs), nframes);
+        for (size_t i = 1; i < numEffects; ++i)
+            _effects[i]->process(
+                AudioSpan<float>(_outputs), AudioSpan<float>(_outputs), nframes);
+    } else
+        fx::Nothing().process(
+            AudioSpan<float>(_inputs), AudioSpan<float>(_outputs), nframes);
+}
+
+void EffectBus::mixOutputsTo(float* const mainOutput[], float* const mixOutput[], unsigned nframes)
+{
+    const float gainToMain = _gainToMain;
+    const float gainToMix = _gainToMix;
+
+    for (unsigned c = 0; c < EffectChannels; ++c) {
+        absl::Span<const float> fxOut = _outputs.getConstSpan(c);
+        sfz::multiplyAdd(gainToMain, fxOut, absl::Span<float>(mainOutput[c], nframes));
+        sfz::multiplyAdd(gainToMix, fxOut, absl::Span<float>(mixOutput[c], nframes));
+    }
+}
+
+} // namespace sfz

src/sfizz/Effects.h

@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#pragma once
+#include "AudioBuffer.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/span.h"
+#include <array>
+#include <vector>
+#include <memory>
+
+namespace sfz {
+struct Opcode;
+
+enum {
+    // Number of channels processed by effects
+    EffectChannels = 2,
+};
+
+/**
+   @brief Abstract base of SFZ effects
+ */
+class Effect {
+public:
+    virtual ~Effect() {}
+
+    /**
+       @brief Initializes with the given sample rate.
+     */
+    virtual void init(double sampleRate) = 0;
+
+    /**
+       @brief Reset the state to initial.
+     */
+    virtual void clear() = 0;
+
+    /**
+       @brief Computes a cycle of the effect in stereo.
+     */
+    virtual void process(const float* const inputs[], float* const outputs[], unsigned nframes) = 0;
+
+    /**
+       @brief Type of the factory function used to instantiate an effect given
+              the contents of the <effect> block
+     */
+    typedef Effect* (MakeInstance)(absl::Span<const Opcode> members);
+};
+
+/**
+   @brief SFZ effects factory
+ */
+class EffectFactory {
+public:
+    /**
+       @brief Registers all available standard effects into the factory.
+     */
+    void registerStandardEffectTypes();
+
+    /**
+       @brief Registers a user-defined effect into the factory.
+     */
+    void registerEffectType(absl::string_view name, Effect::MakeInstance& make);
+
+    /**
+       @brief Instantiates an effect given the contents of the <effect> block.
+     */
+    Effect* makeEffect(absl::Span<const Opcode> members);
+
+private:
+    struct FactoryEntry {
+        std::string name;
+        Effect::MakeInstance* make;
+    };
+
+    std::vector<FactoryEntry> _entries;
+};
+
+/**
+   @brief Sequence of effects processed in series
+ */
+class EffectBus {
+public:
+    EffectBus();
+    ~EffectBus();
+
+    /**
+       @brief Adds an effect at the end of the bus.
+     */
+    void addEffect(std::unique_ptr<Effect> fx);
+
+    /**
+       @brief Checks whether this bus can produce output.
+     */
+    bool hasNonZeroOutput() const { return _gainToMain != 0 || _gainToMix != 0; }
+
+    /**
+       @brief Sets the amount of effect output going to the main.
+     */
+    void setGainToMain(float gain) { _gainToMain = gain; }
+
+    /**
+       @brief Sets the amount of effect output going to the mix.
+     */
+    void setGainToMix(float gain) { _gainToMix = gain; }
+
+    /**
+       @brief Resets the input buffers to zero.
+     */
+    void clearInputs(unsigned nframes);
+
+    /**
+       @brief Adds some audio into the input buffer.
+     */
+    void addToInputs(const float* const addInput[], float addGain, unsigned nframes);
+
+    /**
+       @brief Initializes all effects in the bus with the given sample rate.
+     */
+    void init(double sampleRate);
+
+    /**
+       @brief Resets the state of all effects in the bus.
+     */
+    void clear();
+
+    /**
+       @brief Computes a cycle of the effect bus.
+     */
+    void process(unsigned nframes);
+
+    /**
+       @brief Mixes the outputs into a pair of stereo signals: Main and Mix.
+     */
+    void mixOutputsTo(float* const mainOutput[], float* const mixOutput[], unsigned nframes);
+
+private:
+    std::vector<std::unique_ptr<Effect>> _effects;
+    AudioBuffer<float> _inputs { EffectChannels, config::defaultSamplesPerBlock };
+    AudioBuffer<float> _outputs { EffectChannels, config::defaultSamplesPerBlock };
+    float _gainToMain = 0.0;
+    float _gainToMix = 0.0;
+};
+
+} // namespace sfz

src/sfizz/Region.cpp

@@ -751,6 +751,20 @@ bool sfz::Region::parseOpcode(const Opcode& opcode)
         setCCPairFromOpcode(opcode, amplitudeEG.ccSustain, Default::egOnCCPercentRange);
         break;
 
+    case hash("effect"): // effect&
+        {
+            const auto effectNumber = opcode.backParameter();
+            if (!effectNumber || *effectNumber < 1 || *effectNumber > config::maxEffectBuses)
+                break;
+            auto value = readOpcode<float>(opcode.value, {0, 100});
+            if (!value)
+                break;
+            if (static_cast<size_t>(*effectNumber + 1) > gainToEffect.size())
+                gainToEffect.resize(*effectNumber + 1);
+            gainToEffect[*effectNumber] = *value / 100;
+            break;
+        }
+
     // Ignored opcodes
     case hash("hichan"):
     case hash("lochan"):
@@ -1091,3 +1105,11 @@ void sfz::Region::offsetAllKeys(int offset) noexcept
         crossfadeKeyOutRange.setEnd(offsetAndClamp(end, offset, Default::keyRange));
     }
 }
+
+float sfz::Region::getGainToEffectBus(unsigned number) const noexcept
+{
+    if (number >= gainToEffect.size())
+        return 0.0;
+
+    return gainToEffect[number];
+}

src/sfizz/Region.h

@@ -39,6 +39,9 @@ struct Region {
     : midiState(midiState), defaultPath(std::move(defaultPath))
     {
         ccSwitched.set();
+
+        gainToEffect.reserve(5); // sufficient room for main and fx1-4
+        gainToEffect.push_back(1.0); // contribute 100% into the main bus
     }
     Region(const Region&) = default;
     ~Region() = default;
@@ -206,6 +209,12 @@ struct Region {
 
     bool hasKeyswitches() const noexcept { return keyswitchDown || keyswitchUp || keyswitch || previousNote; }
 
+    /**
+     * @brief Get the gain this region contributes into the input of the Nth
+     *        effect bus
+     */
+    float getGainToEffectBus(unsigned number) const noexcept;
+
     // Sound source: sample playback
     std::string sample {}; // Sample
     float delay { Default::delay }; // delay
@@ -297,6 +306,10 @@ struct Region {
     EGDescription filterEG;
 
     bool isStereo { false };
+
+    // Effects
+    std::vector<float> gainToEffect;
+
 private:
     const MidiState& midiState;
     bool keySwitched { true };