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76 lines
3.4 KiB
C++
76 lines
3.4 KiB
C++
/* Copyright (C) 2015-2020 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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#ifndef MT32EMU_SAMPLE_RATE_CONVERTER_H
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#define MT32EMU_SAMPLE_RATE_CONVERTER_H
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#include "globals.h"
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#include "Types.h"
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#include "Enumerations.h"
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namespace MT32Emu {
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class Synth;
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/* SampleRateConverter class allows to convert the synthesiser output to any desired sample rate.
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* It processes the completely mixed stereo output signal as it passes the analogue circuit emulation,
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* so emulating the synthesiser output signal passing further through an ADC.
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* Several conversion quality options are provided which allow to trade-off the conversion speed vs. the passband width.
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* All the options except FASTEST guarantee full suppression of the aliasing noise in terms of the 16-bit integer samples.
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*/
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class MT32EMU_EXPORT SampleRateConverter {
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public:
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// Returns the value of AnalogOutputMode for which the output signal may retain its full frequency spectrum
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// at the sample rate specified by the targetSampleRate argument.
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static AnalogOutputMode getBestAnalogOutputMode(double targetSampleRate);
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// Returns the sample rate supported by the sample rate conversion implementation currently in effect
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// that is closest to the one specified by the desiredSampleRate argument.
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static double getSupportedOutputSampleRate(double desiredSampleRate);
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// Creates a SampleRateConverter instance that converts output signal from the synth to the given sample rate
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// with the specified conversion quality.
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SampleRateConverter(Synth &synth, double targetSampleRate, SamplerateConversionQuality quality);
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~SampleRateConverter();
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// Fills the provided output buffer with the results of the sample rate conversion.
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// The input samples are automatically retrieved from the synth as necessary.
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void getOutputSamples(MT32Emu::Bit16s *buffer, unsigned int length);
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// Fills the provided output buffer with the results of the sample rate conversion.
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// The input samples are automatically retrieved from the synth as necessary.
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void getOutputSamples(float *buffer, unsigned int length);
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// Returns the number of samples produced at the internal synth sample rate (32000 Hz)
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// that correspond to the number of samples at the target sample rate.
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// Intended to facilitate audio time synchronisation.
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double convertOutputToSynthTimestamp(double outputTimestamp) const;
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// Returns the number of samples produced at the target sample rate
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// that correspond to the number of samples at the internal synth sample rate (32000 Hz).
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// Intended to facilitate audio time synchronisation.
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double convertSynthToOutputTimestamp(double synthTimestamp) const;
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private:
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const double synthInternalToTargetSampleRateRatio;
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const bool useSynthDelegate;
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void * const srcDelegate;
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}; // class SampleRateConverter
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} // namespace MT32Emu
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#endif // MT32EMU_SAMPLE_RATE_CONVERTER_H
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