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extern/audaspace/src/fx/LowpassCalculator.cpp
- This file was added.
| /******************************************************************************* | |||||
| * 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/LowpassCalculator.h" | |||||
| #include <cmath> | |||||
| AUD_NAMESPACE_BEGIN | |||||
| LowpassCalculator::LowpassCalculator(float frequency, float Q) : | |||||
| m_frequency(frequency), | |||||
| m_Q(Q) | |||||
| { | |||||
| } | |||||
| void LowpassCalculator::recalculateCoefficients(SampleRate rate, std::vector<float> &b, std::vector<float> &a) | |||||
| { | |||||
| float w0 = 2 * M_PI * m_frequency / rate; | |||||
| float alpha = std::sin(w0) / (2 * m_Q); | |||||
| float norm = 1 + alpha; | |||||
| float c = std::cos(w0); | |||||
| a.push_back(1); | |||||
| a.push_back(-2 * c / norm); | |||||
| a.push_back((1 - alpha) / norm); | |||||
| b.push_back((1 - c) / (2 * norm)); | |||||
| b.push_back((1 - c) / norm); | |||||
| b.push_back(b[0]); | |||||
| } | |||||
| AUD_NAMESPACE_END | |||||