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audio/softsynth/mt32/Analog.h

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+/* Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009 Dean Beeler, Jerome Fisher
+ * Copyright (C) 2011-2022 Dean Beeler, Jerome Fisher, Sergey V. Mikayev
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation, either version 2.1 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef MT32EMU_ANALOG_H
+#define MT32EMU_ANALOG_H
+
+#include "globals.h"
+#include "internals.h"
+#include "Enumerations.h"
+#include "Types.h"
+
+namespace MT32Emu {
+
+/* Analog class is dedicated to perform fair emulation of analogue circuitry of hardware units that is responsible
+ * for processing output signal after the DAC. It appears that the analogue circuit labeled "LPF" on the schematic
+ * also applies audible changes to the signal spectra. There is a significant boost of higher frequencies observed
+ * aside from quite poor attenuation of the mirror spectra above 16 kHz which is due to a relatively low filter order.
+ *
+ * As the final mixing of multiplexed output signal is performed after the DAC, this function is migrated here from Synth.
+ * Saying precisely, mixing is performed within the LPF as the entrance resistors are actually components of a LPF
+ * designed using the multiple feedback topology. Nevertheless, the schematic separates them.
+ */
+class Analog {
+public:
+	static Analog *createAnalog(const AnalogOutputMode mode, const bool oldMT32AnalogLPF, const RendererType rendererType);
+
+	virtual ~Analog() {}
+	virtual unsigned int getOutputSampleRate() const = 0;
+	virtual Bit32u getDACStreamsLength(const Bit32u outputLength) const = 0;
+	virtual void setSynthOutputGain(const float synthGain) = 0;
+	virtual void setReverbOutputGain(const float reverbGain, const bool mt32ReverbCompatibilityMode) = 0;
+
+	virtual bool process(IntSample *outStream, const IntSample *nonReverbLeft, const IntSample *nonReverbRight, const IntSample *reverbDryLeft, const IntSample *reverbDryRight, const IntSample *reverbWetLeft, const IntSample *reverbWetRight, Bit32u outLength) = 0;
+	virtual bool process(FloatSample *outStream, const FloatSample *nonReverbLeft, const FloatSample *nonReverbRight, const FloatSample *reverbDryLeft, const FloatSample *reverbDryRight, const FloatSample *reverbWetLeft, const FloatSample *reverbWetRight, Bit32u outLength) = 0;
+};
+
+} // namespace MT32Emu
+
+#endif // #ifndef MT32EMU_ANALOG_H