Differential D1358 Diff 4419 extern/audaspace/src/fx/Envelope.cpp

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extern/audaspace/src/fx/Envelope.cpp

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				/*******************************************************************************
				* Copyright 2009-2015 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