pcm/SoxrResampler: new resampler option using libsoxr

src/pcm/ConfiguredResampler.cxx

@@ -29,6 +29,10 @@
 #include "LibsamplerateResampler.hxx"
 #endif
 
+#ifdef HAVE_SOXR
+#include "SoxrResampler.hxx"
+#endif
+
 #include <string.h>
 
 enum class SelectedResampler {
@@ -37,6 +41,10 @@ enum class SelectedResampler {
 #ifdef HAVE_LIBSAMPLERATE
 	LIBSAMPLERATE,
 #endif
+
+#ifdef HAVE_SOXR
+	SOXR,
+#endif
 };
 
 static SelectedResampler selected_resampler = SelectedResampler::FALLBACK;
@@ -50,6 +58,13 @@ pcm_resampler_global_init(Error &error)
 	if (strcmp(converter, "internal") == 0)
 		return true;
 
+#ifdef HAVE_SOXR
+	if (strcmp(converter, "soxr") == 0) {
+		selected_resampler = SelectedResampler::SOXR;
+		return true;
+	}
+#endif
+
 #ifdef HAVE_LIBSAMPLERATE
 	selected_resampler = SelectedResampler::LIBSAMPLERATE;
 	return pcm_resample_lsr_global_init(converter, error);
@@ -75,6 +90,11 @@ pcm_resampler_create()
 	case SelectedResampler::LIBSAMPLERATE:
 		return new LibsampleratePcmResampler();
 #endif
+
+#ifdef HAVE_SOXR
+	case SelectedResampler::SOXR:
+		return new SoxrPcmResampler();
+#endif
 	}
 
 	gcc_unreachable();

src/pcm/SoxrResampler.cxx

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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 2 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, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "SoxrResampler.hxx"
+#include "AudioFormat.hxx"
+#include "util/ASCII.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+#include "Log.hxx"
+
+#include <soxr.h>
+
+#include <assert.h>
+
+static constexpr Domain soxr_domain("soxr");
+
+AudioFormat
+SoxrPcmResampler::Open(AudioFormat &af, unsigned new_sample_rate,
+		       Error &error)
+{
+	assert(af.IsValid());
+	assert(audio_valid_sample_rate(new_sample_rate));
+
+	soxr_error_t e;
+	soxr = soxr_create(af.sample_rate, new_sample_rate,
+			   af.channels, &e,
+			   nullptr, nullptr, nullptr);
+	if (soxr == nullptr) {
+		error.Format(soxr_domain,
+			     "soxr initialization has failed: %s", e);
+		return AudioFormat::Undefined();
+	}
+
+	FormatDebug(soxr_domain, "soxr engine '%s'", soxr_engine(soxr));
+
+	channels = af.channels;
+
+	ratio = float(new_sample_rate) / float(af.sample_rate);
+	FormatDebug(soxr_domain,
+		    "samplerate conversion ratio to %.2lf",
+		    ratio);
+
+	/* libsoxr works with floating point samples */
+	af.format = SampleFormat::FLOAT;
+
+	AudioFormat result = af;
+	result.sample_rate = new_sample_rate;
+	return result;
+}
+
+void
+SoxrPcmResampler::Close()
+{
+	soxr_delete(soxr);
+}
+
+ConstBuffer<void>
+SoxrPcmResampler::Resample(ConstBuffer<void> src, Error &error)
+{
+	const size_t frame_size = channels * sizeof(float);
+	assert(src.size % frame_size == 0);
+
+	const size_t n_frames = src.size / frame_size;
+
+	const size_t o_frames = size_t(n_frames * ratio + 0.5);
+
+	float *output_buffer = (float *)buffer.Get(o_frames * frame_size);
+
+	size_t i_done, o_done;
+	soxr_error_t e = soxr_process(soxr, src.data, n_frames, &i_done,
+				      output_buffer, o_frames, &o_done);
+	if (e != nullptr) {
+		error.Format(soxr_domain, "soxr error: %s", e);
+		return nullptr;
+	}
+
+	return { output_buffer, o_done * frame_size };
+}

src/pcm/SoxrResampler.hxx

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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 2 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, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_PCM_SOXR_RESAMPLER_HXX
+#define MPD_PCM_SOXR_RESAMPLER_HXX
+
+#include "Resampler.hxx"
+#include "PcmBuffer.hxx"
+
+struct AudioFormat;
+
+/**
+ * A resampler using soxr.
+ */
+class SoxrPcmResampler final : public PcmResampler {
+	struct soxr *soxr;
+
+	unsigned channels;
+	float ratio;
+
+	PcmBuffer buffer;
+
+public:
+	virtual AudioFormat Open(AudioFormat &af, unsigned new_sample_rate,
+				 Error &error) override;
+	virtual void Close() override;
+	virtual ConstBuffer<void> Resample(ConstBuffer<void> src,
+					   Error &error) override;
+};
+
+#endif