77 lines
2.9 KiB
C++
77 lines
2.9 KiB
C++
/**
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* @author Bojan MARKOVIC
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* @author Edouard DUPIN
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* @copyright 2006, ChunkWare Music Software, OPEN-SOURCE
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* @license BSD-1 (see license file)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* * The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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#include <audio/algo/chunkware/Gate.h>
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audio::algo::chunkware::Gate::Gate() :
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AttRelEnvelope(1.0, 100.0),
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m_threshdB(0.0),
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m_threshold(1.0),
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m_overThresholdEnvelope(DC_OFFSET) {
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}
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void audio::algo::chunkware::Gate::setThresh(double _dB) {
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m_threshdB = _dB;
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m_threshold = dB2lin(_dB);
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}
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void audio::algo::chunkware::Gate::initRuntime() {
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m_overThresholdEnvelope = DC_OFFSET;
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}
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void audio::algo::chunkware::Gate::process(double& _in1, double& _in2) {
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// create sidechain
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double rect1 = fabs(_in1); // rectify input
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double rect2 = fabs(_in2);
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/* if desired, one could use another EnvelopeDetector to smooth
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* the rectified signal.
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*/
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double link = std::max(rect1, rect2); // link channels with greater of 2
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process(_in1, _in2, link); // rest of process
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}
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void audio::algo::chunkware::Gate::process(double& _in1, double& _in2, double _keyLinked) {
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_keyLinked = fabs(_keyLinked); // rectify (just in case)
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// threshold
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// key over threshold (0.0 or 1.0)
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double over = double(_keyLinked > m_threshold);
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// attack/release
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over += DC_OFFSET; // add DC offset to avoid denormal
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audio::algo::chunkware::AttRelEnvelope::run(over, m_overThresholdEnvelope); // run attack/release
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over = m_overThresholdEnvelope - DC_OFFSET; // subtract DC offset
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/* REGARDING THE DC OFFSET: In this case, since the offset is added before
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* the attack/release processes, the envelope will never fall below the offset,
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* thereby avoiding denormals. However, to prevent the offset from causing
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* constant gain reduction, we must subtract it from the envelope, yielding
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* a minimum value of 0dB.
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*/
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// output gain
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_in1 *= over; // apply gain reduction to input
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_in2 *= over;
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}
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