From 287832e2004f41be6ade99cd43e99ab8cd6803f8 Mon Sep 17 00:00:00 2001
From: Paul Ferrand <paul@ferrand.cc>
Date: Fri, 19 Mar 2021 21:26:14 +0100
Subject: [PATCH] Free-run the envelope if the sustain value is low enough
 Value taken from Sforzando

---
 src/sfizz/ADSREnvelope.cpp | 2 +-
 src/sfizz/Config.h         | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/sfizz/ADSREnvelope.cpp b/src/sfizz/ADSREnvelope.cpp
index be5b3199..b0c10d6e 100644
--- a/src/sfizz/ADSREnvelope.cpp
+++ b/src/sfizz/ADSREnvelope.cpp
@@ -52,7 +52,7 @@ void ADSREnvelope::reset(const EGDescription& desc, const Region& region, const
     sustainThreshold = this->sustain + config::virtuallyZero;
     shouldRelease = false;
     freeRunning = (
-        (this->sustain == Float(0.0))
+        (this->sustain <= Float(config::sustainFreeRunningThreshold))
         || (region.loopMode == LoopMode::one_shot && region.isOscillator())
     );
     currentValue = this->start;
diff --git a/src/sfizz/Config.h b/src/sfizz/Config.h
index 97061613..ac25d3e5 100644
--- a/src/sfizz/Config.h
+++ b/src/sfizz/Config.h
@@ -167,6 +167,11 @@ namespace config {
      * @brief The smoothing time constant per "smooth" steps
      */
     constexpr float smoothTauPerStep { 3e-3 };
+    /**
+     * @brief If a value below this threshold is given to `ampeg_sustain`, the envelope will free-run
+     * and the voice will release itself at the end of the decay stage.
+     */
+    constexpr float sustainFreeRunningThreshold { 0.0032f };
 } // namespace config
 
 } // namespace sfz