Merge pull request #313 from paulfd/xfade-smoothers

Crossfade smoothers

.travis/install_osx.sh

@@ -4,6 +4,7 @@ set -ex
 
 sudo ln -s /usr/local /opt/local
 brew update
+brew upgrade python ||  brew link --overwrite python
 brew upgrade cmake
 brew install jack
 brew install dylibbundler

src/sfizz/Config.h

@@ -41,6 +41,7 @@ namespace config {
     constexpr int numVoices { 64 };
     constexpr unsigned maxVoices { 256 };
     constexpr unsigned smoothingSteps { 512 };
+    constexpr uint8_t xfadeSmoothing { 5 };
     constexpr uint8_t gainSmoothing { 0 };
     constexpr unsigned powerTableSizeExponent { 11 };
     constexpr int maxFilePromises { maxVoices };

src/sfizz/OnePoleFilter.h

@@ -25,6 +25,8 @@ class OnePoleFilter {
 public:
     OnePoleFilter() = default;
 
+    Type current() const { return state; }
+
     void setGain(Type gain)
     {
         G = gain / (1 + gain);

src/sfizz/Smoothers.cpp

@@ -25,12 +25,22 @@ void Smoother::reset(float value)
     filter.reset(value);
 }
 
-void Smoother::process(absl::Span<const float> input, absl::Span<float> output)
+void Smoother::process(absl::Span<const float> input, absl::Span<float> output, bool canShortcut)
 {
-    if (smoothing)
+    CHECK_SPAN_SIZES(input, output);
+    if (input.size() == 0)
+        return;
+
+    if (canShortcut && std::abs(input.front() - current()) < config::virtuallyZero) {
+        if (input.data() != output.data())
+            copy<float>(input, output);
+
+        filter.reset(input.back());
+    } else if (smoothing) {
         filter.processLowpass(input, output);
-    else
+    } else if (input.data() != output.data()) {
         copy<float>(input, output);
+    }
 }
 
 }

src/sfizz/Smoothers.h

@@ -42,9 +42,13 @@ public:
      *
      * @param input
      * @param output
+     * @param canShortcut whether we can have a fast path if the filter is within
+     *                    a reasonable range around the first value of the input
+     *                    span.
      */
-    void process(absl::Span<const float> input, absl::Span<float> output);
+    void process(absl::Span<const float> input, absl::Span<float> output, bool canShortcut = false);
 
+    float current() const { return filter.current(); }
 private:
     bool smoothing { false };
     OnePoleFilter<float> filter {};

src/sfizz/Voice.cpp

@@ -25,6 +25,7 @@ sfz::Voice::Voice(int voiceNumber, sfz::Resources& resources)
         osc.init(sampleRate);
 
     gainSmoother.setSmoothing(config::gainSmoothing, sampleRate);
+    xfadeSmoother.setSmoothing(config::xfadeSmoothing, sampleRate);
 
     for (auto & filter : channelEnvelopeFilters)
         filter.setGain(vaGain(config::filteredEnvelopeCutoff, sampleRate));
@@ -109,6 +110,7 @@ void sfz::Voice::startVoice(Region* region, int delay, int number, float value,
     if (triggerType != TriggerType::CC)
         baseGain *= region->getNoteGain(number, value);
     gainSmoother.reset();
+    resetCrossfades();
 
     // Check that we can handle the number of filters; filters should be cleared here
     ASSERT((filters.capacity() - filters.size()) >= region->filters.size());
@@ -248,6 +250,7 @@ void sfz::Voice::setSampleRate(float sampleRate) noexcept
 {
     this->sampleRate = sampleRate;
     gainSmoother.setSmoothing(config::gainSmoothing, sampleRate);
+    xfadeSmoother.setSmoothing(config::xfadeSmoothing, sampleRate);
 
     for (auto & filter : channelEnvelopeFilters)
         filter.setGain(vaGain(config::filteredEnvelopeCutoff, sampleRate));
@@ -311,11 +314,65 @@ void sfz::Voice::renderBlock(AudioSpan<float> buffer) noexcept
 #endif
 }
 
-void sfz::Voice::amplitudeEnvelope(absl::Span<float> modulationSpan) noexcept
+void sfz::Voice::resetCrossfades() noexcept
+{
+    float xfadeValue { 1.0f };
+    const auto xfCurve = region->crossfadeCCCurve;
+
+    for (const auto& mod : region->crossfadeCCInRange) {
+        const auto value = resources.midiState.getCCValue(mod.cc);
+        xfadeValue *= crossfadeIn(mod.data, value, xfCurve);
+    }
+
+    for (const auto& mod : region->crossfadeCCOutRange) {
+        const auto value = resources.midiState.getCCValue(mod.cc);
+        xfadeValue *= crossfadeOut(mod.data, value, xfCurve);
+    }
+
+    xfadeSmoother.reset(xfadeValue);
+}
+
+void sfz::Voice::applyCrossfades(absl::Span<float> modulationSpan) noexcept
 {
     const auto numSamples = modulationSpan.size();
     const auto xfCurve = region->crossfadeCCCurve;
 
+    auto tempSpan = resources.bufferPool.getBuffer(numSamples);
+    auto xfadeSpan = resources.bufferPool.getBuffer(numSamples);
+
+    if (!tempSpan || !xfadeSpan)
+        return;
+
+    fill<float>(*xfadeSpan, 1.0f);
+
+    bool canShortcut = true;
+    for (const auto& mod : region->crossfadeCCInRange) {
+        const auto events = resources.midiState.getCCEvents(mod.cc);
+        canShortcut &= (events.size() == 1);
+        linearEnvelope(events, *tempSpan, [&](float x) {
+            return crossfadeIn(mod.data, x, xfCurve);
+        });
+        applyGain<float>(*tempSpan, *xfadeSpan);
+    }
+
+    for (const auto& mod : region->crossfadeCCOutRange) {
+        const auto events = resources.midiState.getCCEvents(mod.cc);
+        canShortcut &= (events.size() == 1);
+        linearEnvelope(events, *tempSpan, [&](float x) {
+            return crossfadeOut(mod.data, x, xfCurve);
+        });
+        applyGain<float>(*tempSpan, *xfadeSpan);
+    }
+
+    xfadeSmoother.process(*xfadeSpan, *xfadeSpan, canShortcut);
+    applyGain<float>(*xfadeSpan, modulationSpan);
+}
+
+
+void sfz::Voice::amplitudeEnvelope(absl::Span<float> modulationSpan) noexcept
+{
+    const auto numSamples = modulationSpan.size();
+
     auto tempSpan = resources.bufferPool.getBuffer(numSamples);
     if (!tempSpan)
         return;
@@ -331,22 +388,6 @@ void sfz::Voice::amplitudeEnvelope(absl::Span<float> modulationSpan) noexcept
         applyGain<float>(*tempSpan, modulationSpan);
     });
 
-    // Crossfade envelopes
-    for (const auto& mod : region->crossfadeCCInRange) {
-        const auto events = resources.midiState.getCCEvents(mod.cc);
-        linearEnvelope(events, *tempSpan, [&](float x) {
-            return crossfadeIn(mod.data, x, xfCurve);
-        });
-        applyGain<float>(*tempSpan, modulationSpan);
-    }
-    for (const auto& mod : region->crossfadeCCOutRange) {
-        const auto events = resources.midiState.getCCEvents(mod.cc);
-        linearEnvelope(events, *tempSpan, [&](float x) {
-            return crossfadeOut(mod.data, x, xfCurve);
-        });
-        applyGain<float>(*tempSpan, modulationSpan);
-    }
-
     // Volume envelope
     applyGain1<float>(db2mag(baseVolumedB), modulationSpan);
     forEachWithSmoother(Mod::volume, [&](const CCData<Modifier>& mod, Smoother& smoother) {
@@ -373,6 +414,7 @@ void sfz::Voice::ampStageMono(AudioSpan<float> buffer) noexcept
         return;
 
     amplitudeEnvelope(*modulationSpan);
+    applyCrossfades(*modulationSpan);
     applyGain<float>(*modulationSpan, leftBuffer);
 }
 
@@ -386,6 +428,7 @@ void sfz::Voice::ampStageStereo(AudioSpan<float> buffer) noexcept
         return;
 
     amplitudeEnvelope(*modulationSpan);
+    applyCrossfades(*modulationSpan);
     buffer.applyGain(*modulationSpan);
 }
 

src/sfizz/Voice.h

@@ -340,6 +340,15 @@ private:
      * @param modulationSpan
      */
     void amplitudeEnvelope(absl::Span<float> modulationSpan) noexcept;
+
+    /**
+     * @brief Apply the crossfade envelope to a span.
+     *
+     * @param modulationSpan
+     */
+    void applyCrossfades(absl::Span<float> modulationSpan) noexcept;
+    void resetCrossfades() noexcept;
+
     /**
      * @brief Amplitude stage for a mono source
      *
@@ -473,6 +482,7 @@ private:
     ModifierArray<std::vector<Smoother>> modifierSmoothers;
     Smoother gainSmoother;
     Smoother bendSmoother;
+    Smoother xfadeSmoother;
     void resetSmoothers() noexcept;
 
     std::array<OnePoleFilter<float>, 2> channelEnvelopeFilters;