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/*
* ***** BEGIN GPL LICENSE BLOCK *****
*
* Copyright 2009-2011 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 General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Audaspace; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* ***** END GPL LICENSE BLOCK *****
*/
/** \file audaspace/FX/AUD_EnvelopeFactory.cpp
* \ingroup audfx
*/
#include "AUD_EnvelopeFactory.h"
#include "AUD_CallbackIIRFilterReader.h"
#include <cmath>
struct EnvelopeParameters
{
float attack;
float release;
float threshold;
float arthreshold;
};
sample_t AUD_EnvelopeFactory::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 AUD_EnvelopeFactory::endEnvelopeFilter(EnvelopeParameters* param)
{
delete param;
}
AUD_EnvelopeFactory::AUD_EnvelopeFactory(AUD_Reference<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_Reference<AUD_IReader> AUD_EnvelopeFactory::createReader()
{
AUD_Reference<AUD_IReader> reader = getReader();
EnvelopeParameters* param = new EnvelopeParameters();
param->arthreshold = m_arthreshold;
param->attack = pow(m_arthreshold, 1.0f/(static_cast<float>(reader->getSpecs().rate) * m_attack));
param->release = pow(m_arthreshold, 1.0f/(static_cast<float>(reader->getSpecs().rate) * m_release));
param->threshold = m_threshold;
return new AUD_CallbackIIRFilterReader(reader, 1, 2,
(doFilterIIR) envelopeFilter,
(endFilterIIR) endEnvelopeFilter,
param);
}
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