75 lines
2.9 KiB
C++
75 lines
2.9 KiB
C++
/* Copyright (C) 2015-2022 Sergey V. Mikayev
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "InternalResampler.h"
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#include "srctools/include/SincResampler.h"
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#include "srctools/include/ResamplerModel.h"
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#include "../Synth.h"
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using namespace SRCTools;
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namespace MT32Emu {
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class SynthWrapper : public FloatSampleProvider {
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Synth &synth;
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public:
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SynthWrapper(Synth &useSynth) : synth(useSynth)
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{}
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void getOutputSamples(FloatSample *outBuffer, unsigned int size) {
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synth.render(outBuffer, size);
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}
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};
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static FloatSampleProvider &createModel(Synth &synth, SRCTools::FloatSampleProvider &synthSource, double targetSampleRate, SamplerateConversionQuality quality) {
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static const double MAX_AUDIBLE_FREQUENCY = 20000.0;
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const double sourceSampleRate = synth.getStereoOutputSampleRate();
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if (quality != SamplerateConversionQuality_FASTEST) {
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const bool oversampledMode = synth.getStereoOutputSampleRate() == Synth::getStereoOutputSampleRate(AnalogOutputMode_OVERSAMPLED);
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// Oversampled input allows to bypass IIR interpolation stage and, in some cases, IIR decimation stage
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if (oversampledMode && (0.5 * sourceSampleRate) <= targetSampleRate) {
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// NOTE: In the oversampled mode, the transition band starts at 20kHz and ends at 28kHz
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double passband = MAX_AUDIBLE_FREQUENCY;
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double stopband = 0.5 * sourceSampleRate + MAX_AUDIBLE_FREQUENCY;
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ResamplerStage &resamplerStage = *SincResampler::createSincResampler(sourceSampleRate, targetSampleRate, passband, stopband, ResamplerModel::DEFAULT_DB_SNR, ResamplerModel::DEFAULT_WINDOWED_SINC_MAX_UPSAMPLE_FACTOR);
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return ResamplerModel::createResamplerModel(synthSource, resamplerStage);
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}
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}
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return ResamplerModel::createResamplerModel(synthSource, sourceSampleRate, targetSampleRate, static_cast<ResamplerModel::Quality>(quality));
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}
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} // namespace MT32Emu
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using namespace MT32Emu;
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InternalResampler::InternalResampler(Synth &synth, double targetSampleRate, SamplerateConversionQuality quality) :
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synthSource(*new SynthWrapper(synth)),
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model(createModel(synth, synthSource, targetSampleRate, quality))
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{}
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InternalResampler::~InternalResampler() {
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ResamplerModel::freeResamplerModel(model, synthSource);
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delete &synthSource;
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}
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void InternalResampler::getOutputSamples(float *buffer, unsigned int length) {
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model.getOutputSamples(buffer, length);
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}
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