fresh audaspace from trunk

intern/audaspace/FX/AUD_EnvelopeFactory.cpp

@@ -0,0 +1,78 @@
+/*
+ * $Id$
+ *
+ * ***** BEGIN LGPL LICENSE BLOCK *****
+ *
+ * Copyright 2009 Jörg Hermann Müller
+ *
+ * This file is part of AudaSpace.
+ *
+ * AudaSpace is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * AudaSpace is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with AudaSpace.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * ***** END LGPL LICENSE BLOCK *****
+ */
+
+#include "AUD_EnvelopeFactory.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,
+										 float arthreshold) :
+		AUD_EffectFactory(factory),
+		m_attack(attack),
+		m_release(release),
+		m_threshold(threshold),
+		m_arthreshold(arthreshold)
+{
+}
+
+AUD_IReader* AUD_EnvelopeFactory::createReader() const
+{
+	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);
+}