Let the flex eg free-run when set as the ampeg

src/sfizz/FlexEnvelope.cpp

@@ -45,6 +45,7 @@ struct FlexEnvelope::Impl {
     float currentTime_ { 0.0 };
     absl::optional<size_t> currentFramesUntilRelease_ { absl::nullopt };
     bool isReleased_ { false };
+    bool freeRunning_ { false };
 
     //
     void process(absl::Span<float> out);
@@ -70,6 +71,15 @@ void FlexEnvelope::configure(const FlexEGDescription* desc)
 {
     Impl& impl = *impl_;
     impl.desc_ = desc;
+
+    //
+    impl.freeRunning_ = false;
+    impl.isReleased_ = false;
+
+    //
+    impl.currentStageNumber_ = 0;
+    impl.currentLevel_ = 0.0;
+    impl.currentTime_ = 0.0;
 }
 
 void FlexEnvelope::start(unsigned triggerDelay)
@@ -90,12 +100,12 @@ void FlexEnvelope::start(unsigned triggerDelay)
     impl.stageSustained_ = desc.sustain == 0;
     impl.stageCurve_ = &point.curve();
     impl.currentFramesUntilRelease_ = absl::nullopt;
-    impl.isReleased_ = false;
+}
 
-    //
-    impl.currentStageNumber_ = 0;
-    impl.currentLevel_ = 0.0;
-    impl.currentTime_ = 0.0;
+void FlexEnvelope::setFreeRunning(bool freeRunning)
+{
+    Impl& impl = *impl_;
+    impl.freeRunning_ = freeRunning;
 }
 
 void FlexEnvelope::release(unsigned releaseDelay)
@@ -134,7 +144,6 @@ void FlexEnvelope::Impl::process(absl::Span<float> out)
     const FlexEGDescription& desc = *desc_;
     size_t numFrames = out.size();
     const float samplePeriod = samplePeriod_;
-
     // Skip the initial delay, for frame-accurate trigger
     size_t skipFrames = std::min(numFrames, delayFramesLeft_);
     if (skipFrames > 0) {
@@ -171,9 +180,9 @@ void FlexEnvelope::Impl::process(absl::Span<float> out)
                 }
             }
         }
-        while (!stageSustained_ && currentTime_ >= stageTime_) {
+        while ((!stageSustained_ || freeRunning_) && currentTime_ >= stageTime_) {
             // advance through completed timed stages
-            ASSERT(isReleased_ || !stageSustained_);
+            ASSERT(isReleased_ || !stageSustained_ || freeRunning_);
             if (stageTime_ == 0) {
                 // if stage is of zero duration, immediate transition to level
                 currentLevel_ = stageTargetLevel_;

src/sfizz/FlexEnvelope.h

@@ -30,6 +30,13 @@ public:
      */
     void configure(const FlexEGDescription* desc);
 
+    /**
+     * @brief Set the EG to be freeRunning or not
+     *
+     * @param freeRunning
+     */
+    void setFreeRunning(bool freeRunning);
+
     /**
        Start processing an EG as a region is triggered.
      */

src/sfizz/modulations/sources/FlexEnvelope.cpp

@@ -38,6 +38,12 @@ void FlexEnvelopeSource::init(const ModKey& sourceKey, NumericId<Voice> voiceId,
 
     FlexEnvelope* eg = voice->getFlexEG(egIndex);
     eg->configure(&region->flexEGs[egIndex]);
+    bool freeRunning = (
+        (region->loopMode == SfzLoopMode::one_shot && region->isOscillator())
+    );
+    if (freeRunning && region->flexAmpEG && egIndex == *region->flexAmpEG)
+        eg->setFreeRunning(true);
+
     eg->start(delay);
 }
 

tests/FlexEGT.cpp

@@ -6,6 +6,7 @@
 
 
 #include "sfizz/Synth.h"
+#include "sfizz/AudioBuffer.h"
 #include "sfizz/FlexEnvelope.h"
 #include "catch2/catch.hpp"
 #include "TestHelpers.h"
@@ -357,3 +358,61 @@ TEST_CASE("[FlexEG] Early release")
         }
     }
 }
+
+TEST_CASE("[FlexEG] Free-running flex AmpEG (no sustain)")
+{
+    sfz::Synth synth;
+
+    synth.loadSfzString(fs::current_path(), R"(
+        <region> sample=*noise
+            key=60
+            loop_mode=one_shot
+            eg1_ampeg=1
+            eg1_time1=0    eg1_level1=1
+            eg1_time2=0.03 eg1_level2=0.6
+            eg1_time3=0.06 eg1_level3=0.3
+            eg1_time4=0.12 eg1_level4=0.1
+            eg1_time5=0.3  eg1_level5=0
+        <region> sample=*noise
+            key=62
+            loop_mode=one_shot
+            eg1_ampeg=1
+            eg1_time1=0    eg1_level1=1
+            eg1_time2=0.03 eg1_level2=0.6
+            eg1_time3=0.06 eg1_level3=0.3
+            eg1_time4=0.12 eg1_level4=0.1
+            eg1_time5=0.3  eg1_level5=0 eg1_sustain=5
+        <region> sample=*noise
+            key=64
+            eg1_ampeg=1
+            eg1_time1=0    eg1_level1=1
+            eg1_time2=0.03 eg1_level2=0.6
+            eg1_time3=0.06 eg1_level3=0.3
+            eg1_time4=0.12 eg1_level4=0.1
+            eg1_time5=0.3  eg1_level5=0 eg1_sustain=5
+    )");
+    synth.noteOn(0, 60, 0);
+    sfz::AudioBuffer<float> buffer { 2, 256 };
+    synth.renderBlock(buffer);
+    REQUIRE( synth.getNumActiveVoices(true) == 1 );
+    for (unsigned i = 0; i < 100; ++i)
+        synth.renderBlock(buffer);
+    REQUIRE( synth.getNumActiveVoices(true) == 0 );
+
+    synth.noteOn(0, 62, 0);
+    synth.renderBlock(buffer);
+    REQUIRE( synth.getNumActiveVoices(true) == 1 );
+    for (unsigned i = 0; i < 100; ++i)
+        synth.renderBlock(buffer);
+    REQUIRE( synth.getNumActiveVoices(true) == 0 );
+
+    synth.noteOn(0, 64, 0);
+    synth.renderBlock(buffer);
+    REQUIRE( synth.getNumActiveVoices(true) == 1 );
+    for (unsigned i = 0; i < 100; ++i)
+        synth.renderBlock(buffer);
+    REQUIRE( synth.getNumActiveVoices(true) == 1 );
+    synth.noteOff(0, 64, 0); // the release stage is 0 duration
+    synth.renderBlock(buffer);
+    REQUIRE( synth.getNumActiveVoices(true) == 0 );
+}