fixed point resampling option

main/resample16.c

@@ -0,0 +1,163 @@
+/* 
+ *  Squeezelite - lightweight headless squeezebox emulator
+ *
+ *  (c) Adrian Smith 2012-2015, triode1@btinternet.com
+ *      Ralph Irving 2015-2017, ralph_irving@hotmail.com
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+// upsampling using libsoxr - only included if RESAMPLE set
+
+#include "squeezelite.h"
+
+#if RESAMPLE16
+
+#include <resample16.h>
+
+extern log_level loglevel;
+
+struct resample16 {
+	struct resample16_s *resampler;
+	bool max_rate;
+	bool exception;
+	bool interp;
+	resample16_filter_e filter;
+};
+
+static struct resample16 r;
+
+void resample_samples(struct processstate *process) {
+	ssize_t odone;
+	
+	odone = resample16(r.resampler, (HWORD*) process->inbuf, process->in_frames, (HWORD*) process->outbuf);
+
+	if (odone < 0) {
+		LOG_INFO("resample16 error");
+		return;
+	}
+	
+	process->out_frames = odone;
+	process->total_in  += process->in_frames;
+	process->total_out += odone;
+}
+
+bool resample_drain(struct processstate *process) {
+	process->out_frames = 0;
+	
+	LOG_INFO("resample track complete");
+
+	resample16_delete(r.resampler);
+	r.resampler = NULL;
+
+	return true;
+}
+
+bool resample_newstream(struct processstate *process, unsigned raw_sample_rate, unsigned supported_rates[]) {
+	unsigned outrate = 0;
+	int i;
+
+	if (r.exception) {
+		// find direct match - avoid resampling
+		for (i = 0; supported_rates[i]; i++) {
+			if (raw_sample_rate == supported_rates[i]) {
+				outrate = raw_sample_rate;
+				break;
+			}
+		}
+		// else find next highest sync sample rate
+		while (!outrate && i >= 0) {
+			if (supported_rates[i] > raw_sample_rate && supported_rates[i] % raw_sample_rate == 0) {
+				outrate = supported_rates[i];
+				break;
+			}
+			i--;
+		}
+	}
+
+	if (!outrate) {
+		if (r.max_rate) {
+			// resample to max rate for device
+			outrate = supported_rates[0];
+		} else {
+			// resample to max sync sample rate
+			for (i = 0; supported_rates[i]; i++) {
+				if (supported_rates[i] % raw_sample_rate == 0 || raw_sample_rate % supported_rates[i] == 0) {
+					outrate = supported_rates[i];
+					break;
+				}
+			}
+		}
+		if (!outrate) {
+			outrate = supported_rates[0];
+		}
+	}
+
+	process->in_sample_rate = raw_sample_rate;
+	process->out_sample_rate = outrate;
+
+	if (r.resampler) {
+		resample16_delete(r.resampler);
+		r.resampler = NULL;
+	}
+
+	if (raw_sample_rate != outrate) {
+
+		LOG_INFO("resampling from %u -> %u", raw_sample_rate, outrate);
+		r.resampler = resample16_create((float) outrate / raw_sample_rate, RESAMPLE16_SMALL, false);
+
+		return true;
+
+	} else {
+
+		LOG_INFO("disable resampling - rates match");
+		return false;
+	}
+}
+
+void resample_flush(void) {
+	if (r.resampler) {
+		resample16_delete(r.resampler);
+		r.resampler = NULL;
+	}
+}
+
+bool resample_init(char *opt) {
+	char *filter = NULL, *interp = NULL;
+	
+	r.resampler = NULL;
+	r.max_rate = false;
+	r.exception = false;
+
+	if (opt) {
+		filter = next_param(opt, ':');
+		interp = next_param(NULL, ':');
+	}
+
+	if (filter) {
+		if (*filter == 'm') r.filter = RESAMPLE16_SMALL;
+		else r.filter = RESAMPLE16_FAST;
+	}
+
+	if (interp && *interp == 'i') {
+		r.interp = true;	
+	}
+	
+	LOG_INFO("Resampling with filter %d %s", r.filter, r.interp ? "(interpolated)" : "");
+
+	return true;
+}
+
+#endif // #if RESAMPLE16