Initial commit

audio/softsynth/mt32/srchelper/srctools/include/FIRResampler.h

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+/* Copyright (C) 2015-2022 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 SRCTOOLS_FIR_RESAMPLER_H
+#define SRCTOOLS_FIR_RESAMPLER_H
+
+#include "ResamplerStage.h"
+
+namespace SRCTools {
+
+typedef FloatSample FIRCoefficient;
+
+static const unsigned int FIR_INTERPOLATOR_CHANNEL_COUNT = 2;
+
+class FIRResampler : public ResamplerStage {
+public:
+	FIRResampler(const unsigned int upsampleFactor, const double downsampleFactor, const FIRCoefficient kernel[], const unsigned int kernelLength);
+	~FIRResampler();
+
+	void process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength);
+	unsigned int estimateInLength(const unsigned int outLength) const;
+
+private:
+	const struct Constants {
+		// Filter coefficients
+		const FIRCoefficient *taps;
+		// Indicates whether to interpolate filter taps
+		bool usePhaseInterpolation;
+		// Size of array of filter coefficients
+		unsigned int numberOfTaps;
+		// Upsampling factor
+		unsigned int numberOfPhases;
+		// Downsampling factor
+		double phaseIncrement;
+		// Index of last delay line element, generally greater than numberOfTaps to form a proper binary mask
+		unsigned int delayLineMask;
+		// Delay line
+		FloatSample(*ringBuffer)[FIR_INTERPOLATOR_CHANNEL_COUNT];
+
+		Constants(const unsigned int upsampleFactor, const double downsampleFactor, const FIRCoefficient kernel[], const unsigned int kernelLength);
+	} constants;
+	// Index of current sample in delay line
+	unsigned int ringBufferPosition;
+	// Current phase
+	double phase;
+
+	bool needNextInSample() const;
+	void addInSamples(const FloatSample *&inSamples);
+	void getOutSamplesStereo(FloatSample *&outSamples);
+}; // class FIRResampler
+
+} // namespace SRCTools
+
+#endif // SRCTOOLS_FIR_RESAMPLER_H

audio/softsynth/mt32/srchelper/srctools/include/FloatSampleProvider.h

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+/* Copyright (C) 2015-2022 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 SRCTOOLS_FLOAT_SAMPLE_PROVIDER_H
+#define SRCTOOLS_FLOAT_SAMPLE_PROVIDER_H
+
+namespace SRCTools {
+
+typedef float FloatSample;
+
+/** Interface defines an abstract source of samples. It can either define a single channel stream or a stream with interleaved channels. */
+class FloatSampleProvider {
+public:
+	virtual ~FloatSampleProvider() {}
+
+	virtual void getOutputSamples(FloatSample *outBuffer, unsigned int size) = 0;
+};
+
+} // namespace SRCTools
+
+#endif // SRCTOOLS_FLOAT_SAMPLE_PROVIDER_H

audio/softsynth/mt32/srchelper/srctools/include/IIR2xResampler.h

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+/* Copyright (C) 2015-2022 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 SRCTOOLS_IIR_2X_RESAMPLER_H
+#define SRCTOOLS_IIR_2X_RESAMPLER_H
+
+#include "ResamplerStage.h"
+
+namespace SRCTools {
+
+static const unsigned int IIR_RESAMPER_CHANNEL_COUNT = 2;
+static const unsigned int IIR_SECTION_ORDER = 2;
+
+typedef FloatSample IIRCoefficient;
+typedef FloatSample BufferedSample;
+
+typedef BufferedSample SectionBuffer[IIR_SECTION_ORDER];
+
+// Non-trivial coefficients of a 2nd-order section of a parallel bank
+// (zero-order numerator coefficient is always zero, zero-order denominator coefficient is always unity)
+struct IIRSection {
+	IIRCoefficient num1;
+	IIRCoefficient num2;
+	IIRCoefficient den1;
+	IIRCoefficient den2;
+};
+
+class IIRResampler : public ResamplerStage {
+public:
+	enum Quality {
+		// Used when providing custom IIR filter coefficients.
+		CUSTOM,
+		// Use fast elliptic filter with symmetric ripple: N=8, Ap=As=-99 dB, fp=0.125, fs = 0.25 (in terms of sample rate)
+		FAST,
+		// Use average elliptic filter with symmetric ripple: N=12, Ap=As=-106 dB, fp=0.193, fs = 0.25 (in terms of sample rate)
+		GOOD,
+		// Use sharp elliptic filter with symmetric ripple: N=18, Ap=As=-106 dB, fp=0.238, fs = 0.25 (in terms of sample rate)
+		BEST
+	};
+
+	// Returns the retained fraction of the passband for the given standard quality value
+	static double getPassbandFractionForQuality(Quality quality);
+
+protected:
+	explicit IIRResampler(const Quality quality);
+	explicit IIRResampler(const unsigned int useSectionsCount, const IIRCoefficient useFIR, const IIRSection useSections[]);
+	~IIRResampler();
+
+	const struct Constants {
+		// Coefficient of the 0-order FIR part
+		IIRCoefficient fir;
+		// 2nd-order sections that comprise a parallel bank
+		const IIRSection *sections;
+		// Number of 2nd-order sections
+		unsigned int sectionsCount;
+		// Delay line per channel per section
+		SectionBuffer *buffer;
+
+		Constants(const unsigned int useSectionsCount, const IIRCoefficient useFIR, const IIRSection useSections[], const Quality quality);
+	} constants;
+}; // class IIRResampler
+
+class IIR2xInterpolator : public IIRResampler {
+public:
+	explicit IIR2xInterpolator(const Quality quality);
+	explicit IIR2xInterpolator(const unsigned int useSectionsCount, const IIRCoefficient useFIR, const IIRSection useSections[]);
+
+	void process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength);
+	unsigned int estimateInLength(const unsigned int outLength) const;
+
+private:
+	FloatSample lastInputSamples[IIR_RESAMPER_CHANNEL_COUNT];
+	unsigned int phase;
+};
+
+class IIR2xDecimator : public IIRResampler {
+public:
+	explicit IIR2xDecimator(const Quality quality);
+	explicit IIR2xDecimator(const unsigned int useSectionsCount, const IIRCoefficient useFIR, const IIRSection useSections[]);
+
+	void process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength);
+	unsigned int estimateInLength(const unsigned int outLength) const;
+};
+
+} // namespace SRCTools
+
+#endif // SRCTOOLS_IIR_2X_RESAMPLER_H

audio/softsynth/mt32/srchelper/srctools/include/LinearResampler.h

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+/* Copyright (C) 2015-2022 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 SRCTOOLS_LINEAR_RESAMPLER_H
+#define SRCTOOLS_LINEAR_RESAMPLER_H
+
+#include "ResamplerStage.h"
+
+namespace SRCTools {
+
+static const unsigned int LINEAR_RESAMPER_CHANNEL_COUNT = 2;
+
+class LinearResampler : public ResamplerStage {
+public:
+	LinearResampler(double sourceSampleRate, double targetSampleRate);
+	~LinearResampler() {}
+
+	unsigned int estimateInLength(const unsigned int outLength) const;
+	void process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength);
+
+private:
+	const double inputToOutputRatio;
+	double position;
+	FloatSample lastInputSamples[LINEAR_RESAMPER_CHANNEL_COUNT];
+};
+
+} // namespace SRCTools
+
+#endif // SRCTOOLS_LINEAR_RESAMPLER_H

audio/softsynth/mt32/srchelper/srctools/include/ResamplerModel.h

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+/* Copyright (C) 2015-2022 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 SRCTOOLS_RESAMPLER_MODEL_H
+#define SRCTOOLS_RESAMPLER_MODEL_H
+
+#include "FloatSampleProvider.h"
+
+namespace SRCTools {
+
+class ResamplerStage;
+
+/** Model consists of one or more ResampleStage instances connected in a cascade. */
+namespace ResamplerModel {
+
+// Seems to be a good choice for 16-bit integer samples.
+static const double DEFAULT_DB_SNR = 106;
+
+// When using linear interpolation, oversampling factor necessary to achieve the DEFAULT_DB_SNR is about 256.
+// This figure is the upper estimation, and it can be found by analysing the frequency response of the linear interpolator.
+// When less SNR is desired, this value should also decrease in accordance.
+static const unsigned int DEFAULT_WINDOWED_SINC_MAX_DOWNSAMPLE_FACTOR = 256;
+
+// In the default resampler model, the input to the windowed sinc filter is always at least 2x oversampled during upsampling,
+// so oversampling factor of 128 should be sufficient to achieve the DEFAULT_DB_SNR with linear interpolation.
+static const unsigned int DEFAULT_WINDOWED_SINC_MAX_UPSAMPLE_FACTOR = DEFAULT_WINDOWED_SINC_MAX_DOWNSAMPLE_FACTOR / 2;
+
+
+enum Quality {
+	// Use when the speed is more important than the audio quality.
+	FASTEST,
+	// Use FAST quality setting of the IIR stage (50% of passband retained).
+	FAST,
+	// Use GOOD quality setting of the IIR stage (77% of passband retained).
+	GOOD,
+	// Use BEST quality setting of the IIR stage (95% of passband retained).
+	BEST
+};
+
+FloatSampleProvider &createResamplerModel(FloatSampleProvider &source, double sourceSampleRate, double targetSampleRate, Quality quality);
+FloatSampleProvider &createResamplerModel(FloatSampleProvider &source, ResamplerStage **stages, unsigned int stageCount);
+FloatSampleProvider &createResamplerModel(FloatSampleProvider &source, ResamplerStage &stage);
+
+void freeResamplerModel(FloatSampleProvider &model, FloatSampleProvider &source);
+
+} // namespace ResamplerModel
+
+} // namespace SRCTools
+
+#endif // SRCTOOLS_RESAMPLER_MODEL_H

audio/softsynth/mt32/srchelper/srctools/include/ResamplerStage.h

@@ -0,0 +1,38 @@
+/* Copyright (C) 2015-2022 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 SRCTOOLS_RESAMPLER_STAGE_H
+#define SRCTOOLS_RESAMPLER_STAGE_H
+
+#include "FloatSampleProvider.h"
+
+namespace SRCTools {
+
+/** Interface defines an abstract source of samples. It can either define a single channel stream or a stream with interleaved channels. */
+class ResamplerStage {
+public:
+	virtual ~ResamplerStage() {}
+
+	/** Returns a lower estimation of required number of input samples to produce the specified number of output samples. */
+	virtual unsigned int estimateInLength(const unsigned int outLength) const = 0;
+
+	/** Generates output samples. The arguments are adjusted in accordance with the number of samples processed. */
+	virtual void process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength) = 0;
+};
+
+} // namespace SRCTools
+
+#endif // SRCTOOLS_RESAMPLER_STAGE_H

audio/softsynth/mt32/srchelper/srctools/include/SincResampler.h

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+/* Copyright (C) 2015-2022 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 SRCTOOLS_SINC_RESAMPLER_H
+#define SRCTOOLS_SINC_RESAMPLER_H
+
+#include "FIRResampler.h"
+
+namespace SRCTools {
+
+class ResamplerStage;
+
+namespace SincResampler {
+
+	ResamplerStage *createSincResampler(const double inputFrequency, const double outputFrequency, const double passbandFrequency, const double stopbandFrequency, const double dbSNR, const unsigned int maxUpsampleFactor);
+
+	namespace Utils {
+		void computeResampleFactors(unsigned int &upsampleFactor, double &downsampleFactor, const double inputFrequency, const double outputFrequency, const unsigned int maxUpsampleFactor);
+		unsigned int greatestCommonDivisor(unsigned int a, unsigned int b);
+	}
+
+	namespace KaizerWindow {
+		double estimateBeta(double dbRipple);
+		unsigned int estimateOrder(double dbRipple, double fp, double fs);
+		double bessel(const double x);
+		void windowedSinc(FIRCoefficient kernel[], const unsigned int order, const double fc, const double beta, const double amp);
+	}
+
+} // namespace SincResampler
+
+} // namespace SRCTools
+
+#endif // SRCTOOLS_SINC_RESAMPLER_H