1 files changed, 37 insertions, 3 deletions
diff --git a/intern/audaspace/FX/AUD_EnvelopeFactory.cpp b/intern/audaspace/FX/AUD_EnvelopeFactory.cpp
index 1c625067f1c..4777da70404 100644
--- a/intern/audaspace/FX/AUD_EnvelopeFactory.cpp
+++ b/intern/audaspace/FX/AUD_EnvelopeFactory.cpp
@@ -24,7 +24,31 @@
  */
 
 #include "AUD_EnvelopeFactory.h"
-#include "AUD_EnvelopeReader.h"
+#include "AUD_CallbackIIRFilterReader.h"
+
+#include <cmath>
+
+struct EnvelopeParameters
+{
+	float attack;
+	float release;
+	float threshold;
+	float arthreshold;
+};
+
+sample_t envelopeFilter(AUD_CallbackIIRFilterReader* reader, EnvelopeParameters* param)
+{
+	float in = fabs(reader->x(0));
+	float out = reader->y(-1);
+	if(in < param->threshold)
+		in = 0.0f;
+	return (in > out ? param->attack : param->release) * (out - in) + in;
+}
+
+void endEnvelopeFilter(EnvelopeParameters* param)
+{
+	delete param;
+}
 
 AUD_EnvelopeFactory::AUD_EnvelopeFactory(AUD_IFactory* factory, float attack,
 										 float release, float threshold,
@@ -39,6 +63,16 @@ AUD_EnvelopeFactory::AUD_EnvelopeFactory(AUD_IFactory* factory, float attack,
 
 AUD_IReader* AUD_EnvelopeFactory::createReader() const
 {
-	return new AUD_EnvelopeReader(getReader(), m_attack, m_release, m_threshold,
-								  m_arthreshold);
+	AUD_IReader* reader = getReader();
+
+	EnvelopeParameters* param = new EnvelopeParameters();
+	param->arthreshold = m_arthreshold;
+	param->attack = pow(m_arthreshold, 1.0f/(reader->getSpecs().rate * m_attack));
+	param->release = pow(m_arthreshold, 1.0f/(reader->getSpecs().rate * m_release));
+	param->threshold = m_threshold;
+
+	return new AUD_CallbackIIRFilterReader(reader, 1, 2,
+										   (doFilterIIR) envelopeFilter,
+										   (endFilterIIR) endEnvelopeFilter,
+										   param);
 }