MT32: Update Munt to 2.0.3

This update uses upstream commit
777c51cdb4dbb4e02a53c23edea9086f0b600e26.

The new SampleRateConverter is added, but not built as we don't use it.
Also, building it without source changes will need additional include
directories.

This update of Munt reduces the stack size, and thus fixes bug #9630.

1 files changed, 136 insertions, 0 deletions

diff --git a/audio/softsynth/mt32/srchelper/srctools/src/SincResampler.cpp b/audio/softsynth/mt32/srchelper/srctools/src/SincResampler.cpp
new file mode 100644
index 0000000000..3ed028d261
--- /dev/null
+++ b/audio/softsynth/mt32/srchelper/srctools/src/SincResampler.cpp
@@ -0,0 +1,136 @@
+/* Copyright (C) 2015-2017 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/>.
+ */
+
+#include <cmath>
+
+#ifdef SINC_RESAMPLER_DEBUG_LOG
+#include <iostream>
+#endif
+
+#include "SincResampler.h"
+
+#ifndef M_PI
+static const double M_PI = 3.1415926535897932;
+#endif
+
+using namespace SRCTools;
+
+using namespace SincResampler;
+
+using namespace Utils;
+
+void Utils::computeResampleFactors(unsigned int &upsampleFactor, double &downsampleFactor, const double inputFrequency, const double outputFrequency, const unsigned int maxUpsampleFactor) {
+	static const double RATIONAL_RATIO_ACCURACY_FACTOR = 1E15;
+
+	upsampleFactor = static_cast<unsigned int>(outputFrequency);
+	unsigned int downsampleFactorInt = static_cast<unsigned int>(inputFrequency);
+	if ((upsampleFactor == outputFrequency) && (downsampleFactorInt == inputFrequency)) {
+		// Input and output frequencies are integers, try to reduce them
+		const unsigned int gcd = greatestCommonDivisor(upsampleFactor, downsampleFactorInt);
+		if (gcd > 1) {
+			upsampleFactor /= gcd;
+			downsampleFactor = downsampleFactorInt / gcd;
+		} else {
+			downsampleFactor = downsampleFactorInt;
+		}
+		if (upsampleFactor <= maxUpsampleFactor) return;
+	} else {
+		// Try to recover rational resample ratio by brute force
+		double inputToOutputRatio = inputFrequency / outputFrequency;
+		for (unsigned int i = 1; i <= maxUpsampleFactor; ++i) {
+			double testFactor = inputToOutputRatio * i;
+			if (floor(RATIONAL_RATIO_ACCURACY_FACTOR * testFactor + 0.5) == RATIONAL_RATIO_ACCURACY_FACTOR * floor(testFactor + 0.5)) {
+				// inputToOutputRatio found to be rational within the accuracy
+				upsampleFactor = i;
+				downsampleFactor = floor(testFactor + 0.5);
+				return;
+			}
+		}
+	}
+	// Use interpolation of FIR taps as the last resort
+	upsampleFactor = maxUpsampleFactor;
+	downsampleFactor = maxUpsampleFactor * inputFrequency / outputFrequency;
+}
+
+unsigned int Utils::greatestCommonDivisor(unsigned int a, unsigned int b) {
+	while (0 < b) {
+		unsigned int r = a % b;
+		a = b;
+		b = r;
+	}
+	return a;
+}
+
+double KaizerWindow::estimateBeta(double dbRipple) {
+	return 0.1102 * (dbRipple - 8.7);
+}
+
+unsigned int KaizerWindow::estimateOrder(double dbRipple, double fp, double fs) {
+	const double transBW = (fs - fp);
+	return static_cast<unsigned int>(ceil((dbRipple - 8) / (2.285 * 2 * M_PI * transBW)));
+}
+
+double KaizerWindow::bessel(const double x) {
+	static const double EPS = 1.11E-16;
+
+	double sum = 0.0;
+	double f = 1.0;
+	for (unsigned int i = 1;; ++i) {
+		f *= (0.5 * x / i);
+		double f2 = f * f;
+		if (f2 <= sum * EPS) break;
+		sum += f2;
+	}
+	return 1.0 + sum;
+}
+
+void KaizerWindow::windowedSinc(FIRCoefficient kernel[], const unsigned int order, const double fc, const double beta, const double amp) {
+	const double fc_pi = M_PI * fc;
+	const double recipOrder = 1.0 / order;
+	const double mult = 2.0 * fc * amp / bessel(beta);
+	for (int i = order, j = 0; 0 <= i; i -= 2, ++j) {
+		double xw = i * recipOrder;
+		double win = bessel(beta * sqrt(fabs(1.0 - xw * xw)));
+		double xs = i * fc_pi;
+		double sinc = (i == 0) ? 1.0 : sin(xs) / xs;
+		FIRCoefficient imp = FIRCoefficient(mult * sinc * win);
+		kernel[j] = imp;
+		kernel[order - j] = imp;
+	}
+}
+
+ResamplerStage *SincResampler::createSincResampler(const double inputFrequency, const double outputFrequency, const double passbandFrequency, const double stopbandFrequency, const double dbSNR, const unsigned int maxUpsampleFactor) {
+	unsigned int upsampleFactor;
+	double downsampleFactor;
+	computeResampleFactors(upsampleFactor, downsampleFactor, inputFrequency, outputFrequency, maxUpsampleFactor);
+	double baseSamplePeriod = 1.0 / (inputFrequency * upsampleFactor);
+	double fp = passbandFrequency * baseSamplePeriod;
+	double fs = stopbandFrequency * baseSamplePeriod;
+	double fc = 0.5 * (fp + fs);
+	double beta = KaizerWindow::estimateBeta(dbSNR);
+	unsigned int order = KaizerWindow::estimateOrder(dbSNR, fp, fs);
+	const unsigned int kernelLength = order + 1;
+
+#ifdef SINC_RESAMPLER_DEBUG_LOG
+	std::clog << "FIR: " << upsampleFactor << "/" << downsampleFactor << ", N=" << kernelLength << ", NPh=" << kernelLength / double(upsampleFactor) << ", C=" << 0.5 / fc << ", fp=" << fp << ", fs=" << fs << ", M=" << maxUpsampleFactor << std::endl;
+#endif
+
+	FIRCoefficient *windowedSincKernel = new FIRCoefficient[kernelLength];
+	KaizerWindow::windowedSinc(windowedSincKernel, order, fc, beta, upsampleFactor);
+	ResamplerStage *windowedSincStage = new FIRResampler(upsampleFactor, downsampleFactor, windowedSincKernel, kernelLength);
+	delete[] windowedSincKernel;
+	return windowedSincStage;
+}