pcm/SoxrResampler: new resampler option using libsoxr

Makefile.am

@@ -347,10 +347,12 @@ libpcm_a_SOURCES = \
 	src/pcm/PcmPrng.hxx \
 	src/pcm/PcmUtils.hxx
 libpcm_a_CPPFLAGS = $(AM_CPPFLAGS) \
+	$(SOXR_CFLAGS) \
 	$(SAMPLERATE_CFLAGS)
 
 PCM_LIBS = \
 	libpcm.a \
+	$(SOXR_LIBS) \
 	$(SAMPLERATE_LIBS)
 
 if HAVE_LIBSAMPLERATE
@@ -358,6 +360,11 @@ libpcm_a_SOURCES += \
 	src/pcm/LibsamplerateResampler.cxx src/pcm/LibsamplerateResampler.hxx
 endif
 
+if HAVE_SOXR
+libpcm_a_SOURCES += \
+	src/pcm/SoxrResampler.cxx src/pcm/SoxrResampler.hxx
+endif
+
 # File system library
 
 libfs_a_SOURCES = \

NEWS

 ver 0.19 (not yet released)
+* new resampler option using libsoxr
 
 ver 0.18.5 (2013/11/23)
 * configuration

configure.ac

@@ -360,6 +360,11 @@ AC_ARG_ENABLE(lsr,
 		[enable libsamplerate support]),,
 	enable_lsr=auto)
 
+AC_ARG_ENABLE(soxr,
+	AS_HELP_STRING([--enable-soxr],
+		[enable the libsoxr resampler]),,
+	enable_soxr=auto)
+
 AC_ARG_ENABLE(mad,
 	AS_HELP_STRING([--enable-mad],
 		[enable libmad mp3 decoder plugin]),,
@@ -765,6 +770,15 @@ if test x$enable_lsr = xyes; then
 fi
 AM_CONDITIONAL(HAVE_LIBSAMPLERATE, test x$enable_lsr = xyes)
 
+dnl ------------------------------ libsoxr ------------------------------------
+MPD_AUTO_PKG(soxr, SOXR, [soxr],
+	[libsoxr resampler], [libsoxr not found])
+if test x$enable_soxr = xyes; then
+	AC_DEFINE([HAVE_SOXR], 1, [Define to enable libsoxr])
+fi
+
+AM_CONDITIONAL(HAVE_SOXR, test x$enable_soxr = xyes)
+
 dnl ---------------------------------------------------------------------------
 dnl Input Plugins
 dnl ---------------------------------------------------------------------------
@@ -1626,6 +1640,7 @@ results(wildmidi, [WildMidi])
 
 printf '\nOther features:\n\t'
 results(lsr, [libsamplerate])
+results(soxr, [libsoxr])
 results(libmpdclient, [libmpdclient])
 results(inotify, [inotify])
 results(sqlite, [SQLite])

doc/user.xml

@@ -655,6 +655,14 @@ systemctl start mpd.socket</programlisting>
 
           <listitem>
             <para>
+              <ulink
+              url="http://sourceforge.net/projects/soxr/">libsoxr</ulink>,
+              the SoX Resampler library
+            </para>
+          </listitem>
+
+          <listitem>
+            <para>
               internal: low CPU usage, but very poor quality.  This is
               the fallback if MPD was compiled without an external
               resampler.
@@ -692,6 +700,15 @@ systemctl start mpd.socket</programlisting>
 
               <row>
                 <entry>
+                  "<parameter>soxr</parameter>"
+                </entry>
+                <entry>
+                  Use libsoxr.
+                </entry>
+              </row>
+
+              <row>
+                <entry>
                   "<parameter>Best Sinc Interpolator</parameter>" or
                   "<parameter>0</parameter>"
                 </entry>

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

+/*
+ * 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

+/*
+ * 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