Use the soft engine polyphony limit

src/sfizz/SisterVoiceRing.h

@@ -61,13 +61,14 @@ struct SisterVoiceRing {
      *
      * @param voice
      * @param delay
+     * @param fast whether to apply a fast release
      */
     template<class T,
         absl::enable_if_t<std::is_same<Voice, absl::remove_const_t<T>>::value, int> = 0>
-    static void offAllSisters(T* voice, int delay) {
+    static void offAllSisters(T* voice, int delay, bool fast = false) {
         if (voice != nullptr) {
             SisterVoiceRing::applyToRing(voice, [&] (Voice* v) {
-                v->off(delay);
+                v->off(delay, fast);
             });
         }
     }

src/sfizz/Synth.cpp

@@ -71,6 +71,7 @@ void sfz::Synth::onVoiceStateChanged(NumericId<Voice> id, Voice::State state)
     if (state == Voice::State::idle) {
         auto voice = getVoiceById(id);
         RegionSet::removeVoiceFromHierarchy(voice->getRegion(), voice);
+        engineSet->removeVoice(voice);
         polyphonyGroups[voice->getRegion()->group].removeVoice(voice);
     }
 
@@ -744,7 +745,7 @@ sfz::Voice* sfz::Synth::findFreeVoice() noexcept
     if (freeVoice != voices.end())
         return freeVoice->get();
 
-    DBG("Engine polyphony reached");
+    DBG("Engine hard polyphony reached");
     return {};
 }
 
@@ -972,6 +973,7 @@ void sfz::Synth::startVoice(Region* region, int delay, const TriggerEvent& trigg
     checkRegionPolyphony(region, delay);
     checkGroupPolyphony(region, delay);
     checkSetPolyphony(region, delay);
+    checkEnginePolyphony(delay);
 
     Voice* selectedVoice = findFreeVoice();
     if (selectedVoice == nullptr)
@@ -980,6 +982,7 @@ void sfz::Synth::startVoice(Region* region, int delay, const TriggerEvent& trigg
     ASSERT(selectedVoice->isFree());
     selectedVoice->startVoice(region, delay, triggerEvent);
     ring.addVoiceToRing(selectedVoice);
+    engineSet->registerVoice(selectedVoice);
     RegionSet::registerVoiceInHierarchy(region, selectedVoice);
     polyphonyGroups[region->group].registerVoice(selectedVoice);
 }
@@ -1108,6 +1111,19 @@ void sfz::Synth::checkSetPolyphony(const Region* region, int delay) noexcept
     }
 }
 
+void sfz::Synth::checkEnginePolyphony(int delay) noexcept
+{
+    auto& activeVoices = engineSet->getActiveVoices();
+
+    if (activeVoices.size() >= static_cast<size_t>(numRequiredVoices)) {
+        tempPolyphonyArray.clear();
+        absl::c_copy_if(activeVoices,
+            std::back_inserter(tempPolyphonyArray), [](Voice* v) { return !v->releasedOrFree(); });
+        const auto voiceToSteal = stealer.steal(absl::MakeSpan(tempPolyphonyArray));
+        SisterVoiceRing::offAllSisters(voiceToSteal, delay, true);
+    }
+}
+
 void sfz::Synth::noteOnDispatch(int delay, int noteNumber, float velocity) noexcept
 {
     const auto randValue = randNoteDistribution(Random::randomGenerator);

src/sfizz/Synth.h

@@ -865,6 +865,13 @@ private:
      */
     void checkSetPolyphony(const Region* region, int delay) noexcept;
 
+    /**
+     * @brief Check the engine polyphony, fast releasing voices if necessary
+     *
+     * @param delay
+     */
+    void checkEnginePolyphony(int delay) noexcept;
+
     /**
      * @brief Start a voice for a specific region.
      * This will do the needed polyphony checks and voice stealing.

src/sfizz/Voice.cpp

@@ -167,11 +167,11 @@ void sfz::Voice::release(int delay) noexcept
     resources.modMatrix.releaseVoice(id, region->getId(), delay);
 }
 
-void sfz::Voice::off(int delay) noexcept
+void sfz::Voice::off(int delay, bool fast) noexcept
 {
     if (!region->flexAmpEG) {
-        if (region->offMode == SfzOffMode::fast) {
+        if (region->offMode == SfzOffMode::fast || fast) {
-            egAmplitude.setReleaseTime( Default::offTime );
+            egAmplitude.setReleaseTime(Default::offTime);
         } else if (region->offMode == SfzOffMode::time) {
             egAmplitude.setReleaseTime(region->offTime);
         }

src/sfizz/Voice.h

@@ -328,8 +328,9 @@ public:
      *      and set the envelopes if necessary.
      *
      * @param delay
+     * @param fast whether to apply a fast release regardless of the off mode
      */
-    void off(int delay) noexcept;
+    void off(int delay, bool fast = false) noexcept;
 
     /**
      * @brief gets the age of the Voice