Campbell Barton
8c68ed6df1
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79 lines
2.3 KiB
C++
79 lines
2.3 KiB
C++
/*
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* Copyright 2009-2011 Jörg Hermann Müller
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*
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* This file is part of AudaSpace.
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*
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* Audaspace is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* AudaSpace is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Audaspace; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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/** \file audaspace/FX/AUD_EnvelopeFactory.cpp
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* \ingroup audfx
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*/
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#include "AUD_EnvelopeFactory.h"
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#include "AUD_CallbackIIRFilterReader.h"
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#include <cmath>
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struct EnvelopeParameters
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{
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float attack;
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float release;
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float threshold;
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float arthreshold;
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};
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sample_t AUD_EnvelopeFactory::envelopeFilter(AUD_CallbackIIRFilterReader* reader, EnvelopeParameters* param)
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{
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float in = fabs(reader->x(0));
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float out = reader->y(-1);
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if(in < param->threshold)
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in = 0.0f;
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return (in > out ? param->attack : param->release) * (out - in) + in;
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}
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void AUD_EnvelopeFactory::endEnvelopeFilter(EnvelopeParameters* param)
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{
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delete param;
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}
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AUD_EnvelopeFactory::AUD_EnvelopeFactory(boost::shared_ptr<AUD_IFactory> factory, float attack,
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float release, float threshold,
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float arthreshold) :
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AUD_EffectFactory(factory),
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m_attack(attack),
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m_release(release),
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m_threshold(threshold),
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m_arthreshold(arthreshold)
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{
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}
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boost::shared_ptr<AUD_IReader> AUD_EnvelopeFactory::createReader()
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{
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boost::shared_ptr<AUD_IReader> reader = getReader();
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EnvelopeParameters* param = new EnvelopeParameters();
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param->arthreshold = m_arthreshold;
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param->attack = pow(m_arthreshold, 1.0f/(static_cast<float>(reader->getSpecs().rate) * m_attack));
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param->release = pow(m_arthreshold, 1.0f/(static_cast<float>(reader->getSpecs().rate) * m_release));
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param->threshold = m_threshold;
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return boost::shared_ptr<AUD_IReader>(new AUD_CallbackIIRFilterReader(reader, 1, 2,
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(doFilterIIR) envelopeFilter,
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(endFilterIIR) endEnvelopeFilter,
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param));
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}
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