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/*******************************************************************************
* Copyright 2009-2016 Jörg Müller
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
#include "fx/Envelope.h"
#include "fx/CallbackIIRFilterReader.h"
#include <cmath>
AUD_NAMESPACE_BEGIN
struct EnvelopeParameters
{
float attack;
float release;
float threshold;
float arthreshold;
};
sample_t Envelope::envelopeFilter(CallbackIIRFilterReader* reader, EnvelopeParameters* param)
{
float in = std::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 Envelope::endEnvelopeFilter(EnvelopeParameters* param)
{
delete param;
}
Envelope::Envelope(std::shared_ptr<ISound> sound, float attack, float release, float threshold, float arthreshold) :
Effect(sound),
m_attack(attack),
m_release(release),
m_threshold(threshold),
m_arthreshold(arthreshold)
{
}
std::shared_ptr<IReader> Envelope::createReader()
{
std::shared_ptr<IReader> reader = getReader();
EnvelopeParameters* param = new EnvelopeParameters();
param->arthreshold = m_arthreshold;
param->attack = std::pow(m_arthreshold, 1.0f/(static_cast<float>(reader->getSpecs().rate) * m_attack));
param->release = std::pow(m_arthreshold, 1.0f/(static_cast<float>(reader->getSpecs().rate) * m_release));
param->threshold = m_threshold;
return std::shared_ptr<IReader>(new CallbackIIRFilterReader(reader, 1, 2,
(doFilterIIR) envelopeFilter,
(endFilterIIR) endEnvelopeFilter,
param));
}
AUD_NAMESPACE_END
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