Initial commit

audio/softsynth/mt32/srchelper/SamplerateAdapter.cpp

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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/>.
+ */
+
+#include "SamplerateAdapter.h"
+
+#include "../Synth.h"
+
+using namespace MT32Emu;
+
+static const unsigned int CHANNEL_COUNT = 2;
+
+long SamplerateAdapter::getInputSamples(void *cb_data, float **data) {
+	SamplerateAdapter *instance = static_cast<SamplerateAdapter *>(cb_data);
+	unsigned int length = instance->inBufferSize < 1 ? 1 : (MAX_SAMPLES_PER_RUN < instance->inBufferSize ? MAX_SAMPLES_PER_RUN : instance->inBufferSize);
+	instance->synth.render(instance->inBuffer, length);
+	*data = instance->inBuffer;
+	instance->inBufferSize -= length;
+	return length;
+}
+
+SamplerateAdapter::SamplerateAdapter(Synth &useSynth, double targetSampleRate, SamplerateConversionQuality quality) :
+	synth(useSynth),
+	inBuffer(new float[CHANNEL_COUNT * MAX_SAMPLES_PER_RUN]),
+	inBufferSize(MAX_SAMPLES_PER_RUN),
+	inputToOutputRatio(useSynth.getStereoOutputSampleRate() / targetSampleRate),
+	outputToInputRatio(targetSampleRate / useSynth.getStereoOutputSampleRate())
+{
+	int error;
+	int conversionType;
+	switch (quality) {
+	case SamplerateConversionQuality_FASTEST:
+		conversionType = SRC_LINEAR;
+		break;
+	case SamplerateConversionQuality_FAST:
+		conversionType = SRC_SINC_FASTEST;
+		break;
+	case SamplerateConversionQuality_BEST:
+		conversionType = SRC_SINC_BEST_QUALITY;
+		break;
+	case SamplerateConversionQuality_GOOD:
+	default:
+		conversionType = SRC_SINC_MEDIUM_QUALITY;
+		break;
+	};
+	resampler = src_callback_new(getInputSamples, conversionType, CHANNEL_COUNT, &error, this);
+	if (error != 0) {
+		synth.printDebug("SamplerateAdapter: Creation of Samplerate instance failed: %s\n", src_strerror(error));
+		src_delete(resampler);
+		resampler = NULL;
+	}
+}
+
+SamplerateAdapter::~SamplerateAdapter() {
+	delete[] inBuffer;
+	src_delete(resampler);
+}
+
+void SamplerateAdapter::getOutputSamples(float *buffer, unsigned int length) {
+	if (resampler == NULL) {
+		Synth::muteSampleBuffer(buffer, CHANNEL_COUNT * length);
+		return;
+	}
+	while (length > 0) {
+		inBufferSize = static_cast<unsigned int>(length * inputToOutputRatio + 0.5);
+		long gotFrames = src_callback_read(resampler, outputToInputRatio, long(length), buffer);
+		int error = src_error(resampler);
+		if (error != 0) {
+			synth.printDebug("SamplerateAdapter: Samplerate error during processing: %s > resetting\n", src_strerror(error));
+			error = src_reset(resampler);
+			if (error != 0) {
+				synth.printDebug("SamplerateAdapter: Samplerate failed to reset: %s\n", src_strerror(error));
+				src_delete(resampler);
+				resampler = NULL;
+				Synth::muteSampleBuffer(buffer, CHANNEL_COUNT * length);
+				synth.printDebug("SamplerateAdapter: Samplerate disabled\n");
+				return;
+			}
+			continue;
+		}
+		if (gotFrames <= 0) {
+			synth.printDebug("SamplerateAdapter: got %li frames from Samplerate, weird\n", gotFrames);
+		}
+		buffer += CHANNEL_COUNT * gotFrames;
+		length -= gotFrames;
+	}
+}