Add oscillator unison

src/sfizz/Defaults.h

@@ -63,6 +63,10 @@ namespace Default
     // Wavetable oscillator
     constexpr float oscillatorPhase { 0.0 };
     constexpr Range<float> oscillatorPhaseRange { -1.0, 360.0 };
+    constexpr int oscillatorMulti { 1 };
+    constexpr Range<int> oscillatorMultiRange { 1, 9 };
+    constexpr float oscillatorDetune { 0 };
+    constexpr Range<float> oscillatorDetuneRange { -9600, 9600 };
 
     // Instrument setting: voice lifecycle
 	constexpr uint32_t group { 0 };

src/sfizz/Range.h

@@ -28,8 +28,8 @@ public:
     {
 
     }
-    Type getStart() const noexcept { return _start; }
+    constexpr Type getStart() const noexcept { return _start; }
-    Type getEnd() const noexcept { return _end; }
+    constexpr Type getEnd() const noexcept { return _end; }
     /**
      * @brief Get the range as an std::pair of the endpoints
      *

src/sfizz/Region.cpp

@@ -102,6 +102,12 @@ bool sfz::Region::parseOpcode(const Opcode& opcode)
         if (auto value = readBooleanFromOpcode(opcode))
             oscillator = *value;
         break;
+    case hash("oscillator_multi"):
+        setValueFromOpcode(opcode, oscillatorMulti, Default::oscillatorMultiRange);
+        break;
+    case hash("oscillator_detune"):
+        setValueFromOpcode(opcode, oscillatorDetune, Default::oscillatorDetuneRange);
+        break;
 
     // Instrument settings: voice lifecycle
     case hash("group"): // fallthrough

src/sfizz/Region.h

@@ -60,6 +60,13 @@ struct Region {
      * @return false
      */
     bool isGenerator() const noexcept { return sample.size() > 0 ? sample[0] == '*' : false; }
+    /**
+     * @brief Is stereo (has stereo sample or is unison oscillator)?
+     *
+     * @return true
+     * @return false
+     */
+    bool isStereo() const noexcept { return hasStereoSample || ((oscillator || isGenerator()) && oscillatorMulti >= 3); }
     /**
      * @brief Is a looping region (at least potentially)?
      *
@@ -235,6 +242,8 @@ struct Region {
     // Wavetable oscillator
     float oscillatorPhase { Default::oscillatorPhase };
     bool oscillator = false;
+    int oscillatorMulti = Default::oscillatorMulti;
+    float oscillatorDetune = Default::oscillatorDetune;
 
     // Instrument settings: voice lifecycle
     uint32_t group { Default::group }; // group
@@ -318,7 +327,7 @@ struct Region {
     EGDescription pitchEG;
     EGDescription filterEG;
 
-    bool isStereo { false };
+    bool hasStereoSample { false };
 
     // Effects
     std::vector<float> gainToEffect;

src/sfizz/Synth.cpp

@@ -379,7 +379,7 @@ bool sfz::Synth::loadSfzFile(const fs::path& file)
             }
 
             if (fileInformation->numChannels == 2)
-                region->isStereo = true;
+                region->hasStereoSample = true;
 
             // TODO: adjust with LFO targets
             const auto maxOffset = region->offset + region->offsetRandom;

src/sfizz/Voice.cpp

@@ -21,7 +21,8 @@ sfz::Voice::Voice(sfz::Resources& resources)
     filters.reserve(config::filtersPerVoice);
     equalizers.reserve(config::eqsPerVoice);
 
-    waveOscillator.init(sampleRate);
+    for (WavetableOscillator& osc : waveOscillators)
+        osc.init(sampleRate);
 }
 
 void sfz::Voice::startVoice(Region* region, int delay, int number, float value, sfz::Voice::TriggerType triggerType) noexcept
@@ -59,12 +60,18 @@ void sfz::Voice::startVoice(Region* region, int delay, int number, float value,
             wave = resources.wavePool.getWaveSaw();
             break;
         }
-        waveOscillator.setWavetable(wave);
+        for (WavetableOscillator& osc : waveOscillators) {
-        waveOscillator.setPhase(region->getPhase());
+            osc.setWavetable(wave);
+            osc.setPhase(region->getPhase());
+        }
+        setupOscillatorUnison();
     } else if (region->oscillator) {
         const WavetableMulti* wave = resources.wavePool.getFileWave(region->sample);
-        waveOscillator.setWavetable(wave);
+        for (WavetableOscillator& osc : waveOscillators) {
-        waveOscillator.setPhase(region->getPhase());
+            osc.setWavetable(wave);
+            osc.setPhase(region->getPhase());
+        }
+        setupOscillatorUnison();
     } else {
         currentPromise = resources.filePool.getFilePromise(region->sample);
         if (currentPromise == nullptr) {
@@ -83,7 +90,7 @@ void sfz::Voice::startVoice(Region* region, int delay, int number, float value,
     ASSERT((filters.capacity() - filters.size()) >= region->filters.size());
     ASSERT((equalizers.capacity() - equalizers.size()) >= region->equalizers.size());
 
-    const unsigned numChannels = region->isStereo ? 2 : 1;
+    const unsigned numChannels = region->isStereo() ? 2 : 1;
     for (auto& filter: region->filters) {
         auto newFilter = resources.filterPool.getFilter(filter, numChannels, number, value);
         if (newFilter)
@@ -187,7 +194,8 @@ void sfz::Voice::setSampleRate(float sampleRate) noexcept
 {
     this->sampleRate = sampleRate;
 
-    waveOscillator.init(sampleRate);
+    for (WavetableOscillator& osc : waveOscillators)
+        osc.init(sampleRate);
 }
 
 void sfz::Voice::setSamplesPerBlock(int samplesPerBlock) noexcept
@@ -218,7 +226,7 @@ void sfz::Voice::renderBlock(AudioSpan<float> buffer) noexcept
             fillWithData(delayed_buffer);
     }
 
-    if (region->isStereo) {
+    if (region->isStereo()) {
         ampStageStereo(buffer);
         panStageStereo(buffer);
         filterStageStereo(buffer);
@@ -518,9 +526,10 @@ void sfz::Voice::fillWithGenerator(AudioSpan<float> buffer) noexcept
         absl::c_generate(leftSpan, [&](){ return noiseDist(Random::randomGenerator); });
         absl::c_generate(rightSpan, [&](){ return noiseDist(Random::randomGenerator); });
     } else {
-        const auto numSamples = buffer.getNumFrames();
+        const auto numFrames = buffer.getNumFrames();
-        auto frequencies = resources.bufferPool.getBuffer(numSamples);
+
-        auto bends = resources.bufferPool.getBuffer(numSamples);
+        auto frequencies = resources.bufferPool.getBuffer(numFrames);
+        auto bends = resources.bufferPool.getBuffer(numFrames);
         if (!frequencies || !bends)
             return;
 
@@ -544,8 +553,25 @@ void sfz::Voice::fillWithGenerator(AudioSpan<float> buffer) noexcept
             applyGain<float>(*bends, *frequencies);
         }
 
-        waveOscillator.processModulated(frequencies->data(), leftSpan.data(), buffer.getNumFrames());
+        if (waveUnisonSize == 1) {
-        copy<float>(leftSpan, rightSpan);
+            WavetableOscillator& osc = waveOscillators[0];
+            osc.processModulated(frequencies->data(), 1.0, leftSpan.data(), buffer.getNumFrames());
+            copy<float>(leftSpan, rightSpan);
+        }
+        else {
+            buffer.fill(0.0f);
+
+            auto tempSpan = resources.bufferPool.getBuffer(numFrames);
+            if (!tempSpan)
+                return;
+
+            for (unsigned i = 0, n = waveUnisonSize; i < n; ++i) {
+                WavetableOscillator& osc = waveOscillators[i];
+                osc.processModulated(frequencies->data(), waveDetuneRatio[i], tempSpan->data(), numFrames);
+                sfz::multiplyAdd<float>(waveLeftGain[i], *tempSpan, leftSpan);
+                sfz::multiplyAdd<float>(waveRightGain[i], *tempSpan, rightSpan);
+            }
+        }
     }
 }
 
@@ -620,3 +646,60 @@ void sfz::Voice::setMaxEQsPerVoice(size_t numFilters)
     ASSERT(equalizers.size() == 0);
     equalizers.reserve(numFilters);
 }
+
+void sfz::Voice::setupOscillatorUnison()
+{
+    int m = region->oscillatorMulti;
+    float d = region->oscillatorDetune;
+
+    // 3-9: unison mode, 1: normal/RM, 2: PM/FM
+    // TODO(jpc) RM/FM/PM synthesis
+    if (m < 3) {
+        waveUnisonSize = 1;
+        waveDetuneRatio[0] = 1.0;
+        waveLeftGain[0] = 1.0;
+        waveRightGain[0] = 1.0;
+        return;
+    }
+
+    // oscillator count, aka. unison size
+    waveUnisonSize = m;
+
+    // detune (cents)
+    float detunes[maxWaveOscillators];
+    detunes[0] = 0.0;
+    detunes[1] = -d;
+    detunes[2] = +d;
+    for (int i = 3; i < m; ++i)
+        detunes[i] = d * ((i & 1) ? -0.25f : +0.25f) * ((i - 1) / 2);
+
+    // detune (ratio)
+    for (int i = 0; i < m; ++i)
+        waveDetuneRatio[i] = std::exp2(detunes[i] * (0.01f / 12.0f));
+
+    // gains
+    waveLeftGain[0] = 0.0;
+    waveRightGain[m - 1] = 0.0;
+    for (int i = 0; i < m - 1; ++i) {
+        float g = 1 - i / float(m - 1);
+        waveLeftGain[m - 1 - i] = g;
+        waveRightGain[i] = g;
+    }
+
+#if 0
+    fprintf(stderr, "\n");
+    fprintf(stderr, "# Left:\n");
+    for (int i = m - 1; i >= 0; --i) {
+        if (waveLeftGain[i] != 0)
+            fprintf(stderr, "[%d] %10g cents, %10g dB\n", i, detunes[i], 20.0f * std::log10(waveLeftGain[i]));
+    }
+    fprintf(stderr, "\n");
+    fprintf(stderr, "# Right:\n");
+    for (int i = 0; i < m; ++i) {
+        if (waveRightGain[i] != 0)
+            fprintf(stderr, "[%d] %10g cents, %10g dB\n", i, detunes[i], 20.0f * std::log10(waveRightGain[i]));
+    }
+#endif
+}
+
+constexpr unsigned sfz::Voice::maxWaveOscillators;

src/sfizz/Voice.h

@@ -244,6 +244,10 @@ private:
     void panStageStereo(AudioSpan<float> buffer) noexcept;
     void filterStageMono(AudioSpan<float> buffer) noexcept;
     void filterStageStereo(AudioSpan<float> buffer) noexcept;
+    /**
+     * @brief Initialize frequency and gain coefficients for the oscillators.
+     */
+    void setupOscillatorUnison();
 
     Region* region { nullptr };
 
@@ -284,7 +288,15 @@ private:
     ADSREnvelope<float> egEnvelope;
     float bendStepFactor { centsFactor(1) };
 
-    WavetableOscillator waveOscillator;
+    static constexpr unsigned maxWaveOscillators = Default::oscillatorMultiRange.getEnd();
+
+    WavetableOscillator waveOscillators[maxWaveOscillators];
+
+    // unison of oscillators
+    unsigned waveUnisonSize { 0 };
+    float waveDetuneRatio[maxWaveOscillators] { };
+    float waveLeftGain[maxWaveOscillators] { };
+    float waveRightGain[maxWaveOscillators] { };
 
     Duration dataDuration;
     Duration amplitudeDuration;

src/sfizz/Wavetables.cpp

@@ -34,10 +34,10 @@ void WavetableOscillator::setPhase(float phase)
     _phase = phase;
 }
 
-void WavetableOscillator::process(float frequency, float* output, unsigned nframes)
+void WavetableOscillator::process(float frequency, float detuneRatio, float* output, unsigned nframes)
 {
     float phase = _phase;
-    float phaseInc = frequency * _sampleInterval;
+    float phaseInc = frequency * (detuneRatio * _sampleInterval);
 
     const WavetableMulti& multi = *_multi;
     unsigned tableSize = multi.tableSize();
@@ -56,7 +56,7 @@ void WavetableOscillator::process(float frequency, float* output, unsigned nfram
     _phase = phase;
 }
 
-void WavetableOscillator::processModulated(const float* frequencies, float* output, unsigned nframes)
+void WavetableOscillator::processModulated(const float* frequencies, float detuneRatio, float* output, unsigned nframes)
 {
     float phase = _phase;
     float sampleInterval = _sampleInterval;
@@ -66,7 +66,7 @@ void WavetableOscillator::processModulated(const float* frequencies, float* outp
 
     for (unsigned i = 0; i < nframes; ++i) {
         float frequency = frequencies[i];
-        float phaseInc = frequency * sampleInterval;
+        float phaseInc = frequency * (detuneRatio * sampleInterval);
         absl::Span<const float> table = multi.getTableForFrequency(frequency);
 
         float position = phase * tableSize;

src/sfizz/Wavetables.h

@@ -47,12 +47,12 @@ public:
     /**
        Compute a cycle of the oscillator, with constant frequency.
      */
-    void process(float frequency, float* output, unsigned nframes);
+    void process(float frequency, float detuneRatio, float* output, unsigned nframes);
 
     /**
        Compute a cycle of the oscillator, with varying frequency.
      */
-    void processModulated(const float* frequencies, float* output, unsigned nframes);
+    void processModulated(const float* frequencies, float detuneRatio, float* output, unsigned nframes);
 
 private:
     /**

tests/DemoWavetables.cpp

@@ -172,7 +172,7 @@ int DemoApp::processAudio(jack_nframes_t nframes, void* cbdata)
     self->fSweepCurrent = sweepCurrent;
 
     // compute oscillator
-    osc.processModulated(frequency, left, nframes);
+    osc.processModulated(frequency, 1.0, left, nframes);
     std::memcpy(right, left, nframes * sizeof(float));
 
     return 0;