19 files changed, 920 insertions, 6 deletions

diff --git a/src/mixer/MixerAll.cxx b/src/mixer/MixerAll.cxx
new file mode 100644
index 000000000..3cc92baee
--- /dev/null
+++ b/src/mixer/MixerAll.cxx
@@ -0,0 +1,175 @@
+/*
+ * Copyright (C) 2003-2014 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 "MixerAll.hxx"
+#include "MixerControl.hxx"
+#include "MixerInternal.hxx"
+#include "MixerList.hxx"
+#include "output/OutputAll.hxx"
+#include "output/OutputInternal.hxx"
+#include "pcm/Volume.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+#include "Log.hxx"
+
+#include <assert.h>
+
+static constexpr Domain mixer_domain("mixer");
+
+static int
+output_mixer_get_volume(unsigned i)
+{
+	struct audio_output *output;
+	int volume;
+
+	assert(i < audio_output_count());
+
+	output = audio_output_get(i);
+	if (!output->enabled)
+		return -1;
+
+	Mixer *mixer = output->mixer;
+	if (mixer == nullptr)
+		return -1;
+
+	Error error;
+	volume = mixer_get_volume(mixer, error);
+	if (volume < 0 && error.IsDefined())
+		FormatError(error,
+			    "Failed to read mixer for '%s'",
+			    output->name);
+
+	return volume;
+}
+
+int
+mixer_all_get_volume(void)
+{
+	unsigned count = audio_output_count(), ok = 0;
+	int volume, total = 0;
+
+	for (unsigned i = 0; i < count; i++) {
+		volume = output_mixer_get_volume(i);
+		if (volume >= 0) {
+			total += volume;
+			++ok;
+		}
+	}
+
+	if (ok == 0)
+		return -1;
+
+	return total / ok;
+}
+
+static bool
+output_mixer_set_volume(unsigned i, unsigned volume)
+{
+	struct audio_output *output;
+	bool success;
+
+	assert(i < audio_output_count());
+	assert(volume <= 100);
+
+	output = audio_output_get(i);
+	if (!output->enabled)
+		return false;
+
+	Mixer *mixer = output->mixer;
+	if (mixer == nullptr)
+		return false;
+
+	Error error;
+	success = mixer_set_volume(mixer, volume, error);
+	if (!success && error.IsDefined())
+		FormatError(error,
+			    "Failed to set mixer for '%s'",
+			    output->name);
+
+	return success;
+}
+
+bool
+mixer_all_set_volume(unsigned volume)
+{
+	bool success = false;
+	unsigned count = audio_output_count();
+
+	assert(volume <= 100);
+
+	for (unsigned i = 0; i < count; i++)
+		success = output_mixer_set_volume(i, volume)
+			|| success;
+
+	return success;
+}
+
+static int
+output_mixer_get_software_volume(unsigned i)
+{
+	struct audio_output *output;
+
+	assert(i < audio_output_count());
+
+	output = audio_output_get(i);
+	if (!output->enabled)
+		return -1;
+
+	Mixer *mixer = output->mixer;
+	if (mixer == nullptr || !mixer->IsPlugin(software_mixer_plugin))
+		return -1;
+
+	return mixer_get_volume(mixer, IgnoreError());
+}
+
+int
+mixer_all_get_software_volume(void)
+{
+	unsigned count = audio_output_count(), ok = 0;
+	int volume, total = 0;
+
+	for (unsigned i = 0; i < count; i++) {
+		volume = output_mixer_get_software_volume(i);
+		if (volume >= 0) {
+			total += volume;
+			++ok;
+		}
+	}
+
+	if (ok == 0)
+		return -1;
+
+	return total / ok;
+}
+
+void
+mixer_all_set_software_volume(unsigned volume)
+{
+	unsigned count = audio_output_count();
+
+	assert(volume <= PCM_VOLUME_1);
+
+	for (unsigned i = 0; i < count; i++) {
+		struct audio_output *output = audio_output_get(i);
+		if (output->mixer != nullptr &&
+		    output->mixer->plugin == &software_mixer_plugin)
+			mixer_set_volume(output->mixer, volume, IgnoreError());
+	}
+}
diff --git a/src/mixer/MixerAll.hxx b/src/mixer/MixerAll.hxx
new file mode 100644
index 000000000..f868f64b5
--- /dev/null
+++ b/src/mixer/MixerAll.hxx
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2003-2014 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.
+ */
+
+/** \file
+ *
+ * Functions which affect the mixers of all audio outputs.
+ */
+
+#ifndef MPD_MIXER_ALL_HXX
+#define MPD_MIXER_ALL_HXX
+
+#include "Compiler.h"
+
+/**
+ * Returns the average volume of all available mixers (range 0..100).
+ * Returns -1 if no mixer can be queried.
+ */
+gcc_pure
+int
+mixer_all_get_volume(void);
+
+/**
+ * Sets the volume on all available mixers.
+ *
+ * @param volume the volume (range 0..100)
+ * @return true on success, false on failure
+ */
+bool
+mixer_all_set_volume(unsigned volume);
+
+/**
+ * Similar to mixer_all_get_volume(), but gets the volume only for
+ * software mixers.  See #software_mixer_plugin.  This function fails
+ * if no software mixer is configured.
+ */
+gcc_pure
+int
+mixer_all_get_software_volume(void);
+
+/**
+ * Similar to mixer_all_set_volume(), but sets the volume only for
+ * software mixers.  See #software_mixer_plugin.  This function cannot
+ * fail, because the underlying software mixers cannot fail either.
+ */
+void
+mixer_all_set_software_volume(unsigned volume);
+
+#endif
diff --git a/src/mixer/MixerControl.cxx b/src/mixer/MixerControl.cxx
new file mode 100644
index 000000000..bdf6fcc2b
--- /dev/null
+++ b/src/mixer/MixerControl.cxx
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2003-2014 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 "MixerControl.hxx"
+#include "MixerInternal.hxx"
+#include "util/Error.hxx"
+
+#include <assert.h>
+
+Mixer *
+mixer_new(const struct mixer_plugin *plugin, void *ao,
+	  const config_param &param,
+	  Error &error)
+{
+	Mixer *mixer;
+
+	assert(plugin != nullptr);
+
+	mixer = plugin->init(ao, param, error);
+
+	assert(mixer == nullptr || mixer->IsPlugin(*plugin));
+
+	return mixer;
+}
+
+void
+mixer_free(Mixer *mixer)
+{
+	assert(mixer != nullptr);
+	assert(mixer->plugin != nullptr);
+
+	/* mixers with the "global" flag set might still be open at
+	   this point (see mixer_auto_close()) */
+	mixer_close(mixer);
+
+	mixer->plugin->finish(mixer);
+}
+
+bool
+mixer_open(Mixer *mixer, Error &error)
+{
+	bool success;
+
+	assert(mixer != nullptr);
+	assert(mixer->plugin != nullptr);
+
+	const ScopeLock protect(mixer->mutex);
+
+	if (mixer->open)
+		success = true;
+	else if (mixer->plugin->open == nullptr)
+		success = mixer->open = true;
+	else
+		success = mixer->open = mixer->plugin->open(mixer, error);
+
+	mixer->failed = !success;
+
+	return success;
+}
+
+static void
+mixer_close_internal(Mixer *mixer)
+{
+	assert(mixer != nullptr);
+	assert(mixer->plugin != nullptr);
+	assert(mixer->open);
+
+	if (mixer->plugin->close != nullptr)
+		mixer->plugin->close(mixer);
+
+	mixer->open = false;
+}
+
+void
+mixer_close(Mixer *mixer)
+{
+	assert(mixer != nullptr);
+	assert(mixer->plugin != nullptr);
+
+	const ScopeLock protect(mixer->mutex);
+
+	if (mixer->open)
+		mixer_close_internal(mixer);
+}
+
+void
+mixer_auto_close(Mixer *mixer)
+{
+	if (!mixer->plugin->global)
+		mixer_close(mixer);
+}
+
+/*
+ * Close the mixer due to failure.  The mutex must be locked before
+ * calling this function.
+ */
+static void
+mixer_failed(Mixer *mixer)
+{
+	assert(mixer->open);
+
+	mixer_close_internal(mixer);
+
+	mixer->failed = true;
+}
+
+int
+mixer_get_volume(Mixer *mixer, Error &error)
+{
+	int volume;
+
+	assert(mixer != nullptr);
+
+	if (mixer->plugin->global && !mixer->failed &&
+	    !mixer_open(mixer, error))
+		return -1;
+
+	const ScopeLock protect(mixer->mutex);
+
+	if (mixer->open) {
+		volume = mixer->plugin->get_volume(mixer, error);
+		if (volume < 0 && error.IsDefined())
+			mixer_failed(mixer);
+	} else
+		volume = -1;
+
+	return volume;
+}
+
+bool
+mixer_set_volume(Mixer *mixer, unsigned volume, Error &error)
+{
+	assert(mixer != nullptr);
+	assert(volume <= 100);
+
+	if (mixer->plugin->global && !mixer->failed &&
+	    !mixer_open(mixer, error))
+		return false;
+
+	const ScopeLock protect(mixer->mutex);
+
+	return mixer->open &&
+		mixer->plugin->set_volume(mixer, volume, error);
+}
diff --git a/src/mixer/MixerControl.hxx b/src/mixer/MixerControl.hxx
new file mode 100644
index 000000000..caa1c3054
--- /dev/null
+++ b/src/mixer/MixerControl.hxx
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2003-2014 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.
+ */
+
+/** \file
+ *
+ * Functions which manipulate a #mixer object.
+ */
+
+#ifndef MPD_MIXER_CONTROL_HXX
+#define MPD_MIXER_CONTROL_HXX
+
+class Error;
+class Mixer;
+struct mixer_plugin;
+struct config_param;
+
+Mixer *
+mixer_new(const mixer_plugin *plugin, void *ao,
+	  const config_param &param,
+	  Error &error);
+
+void
+mixer_free(Mixer *mixer);
+
+bool
+mixer_open(Mixer *mixer, Error &error);
+
+void
+mixer_close(Mixer *mixer);
+
+/**
+ * Close the mixer unless the plugin's "global" flag is set.  This is
+ * called when the #audio_output is closed.
+ */
+void
+mixer_auto_close(Mixer *mixer);
+
+int
+mixer_get_volume(Mixer *mixer, Error &error);
+
+bool
+mixer_set_volume(Mixer *mixer, unsigned volume, Error &error);
+
+#endif
diff --git a/src/mixer/MixerInternal.hxx b/src/mixer/MixerInternal.hxx
new file mode 100644
index 000000000..1732b4f3b
--- /dev/null
+++ b/src/mixer/MixerInternal.hxx
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2003-2014 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_MIXER_INTERNAL_HXX
+#define MPD_MIXER_INTERNAL_HXX
+
+#include "MixerPlugin.hxx"
+#include "MixerList.hxx"
+#include "thread/Mutex.hxx"
+
+class Mixer {
+public:
+	const struct mixer_plugin *plugin;
+
+	/**
+	 * This mutex protects all of the mixer struct, including its
+	 * implementation, so plugins don't have to deal with that.
+	 */
+	Mutex mutex;
+
+	/**
+	 * Is the mixer device currently open?
+	 */
+	bool open;
+
+	/**
+	 * Has this mixer failed, and should not be reopened
+	 * automatically?
+	 */
+	bool failed;
+
+public:
+	Mixer(const mixer_plugin &_plugin)
+		:plugin(&_plugin),
+		 open(false),
+		 failed(false) {}
+
+	bool IsPlugin(const mixer_plugin &other) const {
+		return plugin == &other;
+	}
+};
+
+#endif
diff --git a/src/mixer/MixerList.hxx b/src/mixer/MixerList.hxx
new file mode 100644
index 000000000..eb3dba938
--- /dev/null
+++ b/src/mixer/MixerList.hxx
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2003-2014 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.
+ */
+
+/** \file
+ *
+ * This header provides "extern" declarations for all mixer plugins.
+ */
+
+#ifndef MPD_MIXER_LIST_HXX
+#define MPD_MIXER_LIST_HXX
+
+extern const struct mixer_plugin software_mixer_plugin;
+extern const struct mixer_plugin alsa_mixer_plugin;
+extern const struct mixer_plugin oss_mixer_plugin;
+extern const struct mixer_plugin roar_mixer_plugin;
+extern const struct mixer_plugin pulse_mixer_plugin;
+extern const struct mixer_plugin winmm_mixer_plugin;
+
+#endif
diff --git a/src/mixer/MixerPlugin.hxx b/src/mixer/MixerPlugin.hxx
new file mode 100644
index 000000000..b29ecbab8
--- /dev/null
+++ b/src/mixer/MixerPlugin.hxx
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2003-2014 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.
+ */
+
+/** \file
+ *
+ * This header declares the mixer_plugin class.  It should not be
+ * included directly; use MixerInternal.hxx instead in mixer
+ * implementations.
+ */
+
+#ifndef MPD_MIXER_PLUGIN_HXX
+#define MPD_MIXER_PLUGIN_HXX
+
+struct config_param;
+class Mixer;
+class Error;
+
+struct mixer_plugin {
+	/**
+         * Alocates and configures a mixer device.
+	 *
+	 * @param ao the pointer returned by audio_output_plugin.init
+	 * @param param the configuration section
+	 * @param error_r location to store the error occurring, or
+	 * nullptr to ignore errors
+	 * @return a mixer object, or nullptr on error
+	 */
+	Mixer *(*init)(void *ao, const config_param &param,
+		       Error &error);
+
+	/**
+	 * Finish and free mixer data
+         */
+	void (*finish)(Mixer *data);
+
+	/**
+	 * Open mixer device
+	 *
+	 * @param error_r location to store the error occurring, or
+	 * nullptr to ignore errors
+	 * @return true on success, false on error
+	 */
+	bool (*open)(Mixer *data, Error &error);
+
+	/**
+	 * Close mixer device
+	 */
+	void (*close)(Mixer *data);
+
+	/**
+	 * Reads the current volume.
+	 *
+	 * @param error_r location to store the error occurring, or
+	 * nullptr to ignore errors
+	 * @return the current volume (0..100 including) or -1 if
+	 * unavailable or on error (error set, mixer will be closed)
+	 */
+	int (*get_volume)(Mixer *mixer, Error &error);
+
+	/**
+	 * Sets the volume.
+	 *
+	 * @param error_r location to store the error occurring, or
+	 * nullptr to ignore errors
+	 * @param volume the new volume (0..100 including)
+	 * @return true on success, false on error
+	 */
+	bool (*set_volume)(Mixer *mixer, unsigned volume,
+			   Error &error);
+
+	/**
+	 * If true, then the mixer is automatically opened, even if
+	 * its audio output is not open.  If false, then the mixer is
+	 * disabled as long as its audio output is closed.
+	 */
+	bool global;
+};
+
+#endif
diff --git a/src/mixer/MixerType.cxx b/src/mixer/MixerType.cxx
new file mode 100644
index 000000000..cd45db0d9
--- /dev/null
+++ b/src/mixer/MixerType.cxx
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2003-2014 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 "MixerType.hxx"
+
+#include <assert.h>
+#include <string.h>
+
+enum mixer_type
+mixer_type_parse(const char *input)
+{
+	assert(input != NULL);
+
+	if (strcmp(input, "none") == 0 || strcmp(input, "disabled") == 0)
+		return MIXER_TYPE_NONE;
+	else if (strcmp(input, "hardware") == 0)
+		return MIXER_TYPE_HARDWARE;
+	else if (strcmp(input, "software") == 0)
+		return MIXER_TYPE_SOFTWARE;
+	else
+		return MIXER_TYPE_UNKNOWN;
+}
diff --git a/src/mixer/MixerType.hxx b/src/mixer/MixerType.hxx
new file mode 100644
index 000000000..bfa2637b7
--- /dev/null
+++ b/src/mixer/MixerType.hxx
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2003-2014 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_MIXER_TYPE_HXX
+#define MPD_MIXER_TYPE_HXX
+
+enum mixer_type {
+	/** parser error */
+	MIXER_TYPE_UNKNOWN,
+
+	/** mixer disabled */
+	MIXER_TYPE_NONE,
+
+	/** software mixer with pcm_volume() */
+	MIXER_TYPE_SOFTWARE,
+
+	/** hardware mixer (output's plugin) */
+	MIXER_TYPE_HARDWARE,
+};
+
+/**
+ * Parses a "mixer_type" setting from the configuration file.
+ *
+ * @param input the configured string value; must not be NULL
+ * @return a #mixer_type value; MIXER_TYPE_UNKNOWN means #input could
+ * not be parsed
+ */
+enum mixer_type
+mixer_type_parse(const char *input);
+
+#endif
diff --git a/src/mixer/Volume.cxx b/src/mixer/Volume.cxx
new file mode 100644
index 000000000..4c897b21f
--- /dev/null
+++ b/src/mixer/Volume.cxx
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2003-2014 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 "Volume.hxx"
+#include "MixerAll.hxx"
+#include "Idle.hxx"
+#include "GlobalEvents.hxx"
+#include "util/StringUtil.hxx"
+#include "util/Domain.hxx"
+#include "system/PeriodClock.hxx"
+#include "Log.hxx"
+
+#include <assert.h>
+#include <stdlib.h>
+
+#define SW_VOLUME_STATE                         "sw_volume: "
+
+static constexpr Domain volume_domain("volume");
+
+static unsigned volume_software_set = 100;
+
+/** the cached hardware mixer value; invalid if negative */
+static int last_hardware_volume = -1;
+/** the age of #last_hardware_volume */
+static PeriodClock hardware_volume_clock;
+
+/**
+ * Handler for #GlobalEvents::MIXER.
+ */
+static void
+mixer_event_callback(void)
+{
+	/* flush the hardware volume cache */
+	last_hardware_volume = -1;
+
+	/* notify clients */
+	idle_add(IDLE_MIXER);
+}
+
+void volume_init(void)
+{
+	GlobalEvents::Register(GlobalEvents::MIXER, mixer_event_callback);
+}
+
+int volume_level_get(void)
+{
+	if (last_hardware_volume >= 0 &&
+	    !hardware_volume_clock.CheckUpdate(1000))
+		/* throttle access to hardware mixers */
+		return last_hardware_volume;
+
+	last_hardware_volume = mixer_all_get_volume();
+	return last_hardware_volume;
+}
+
+static bool software_volume_change(unsigned volume)
+{
+	assert(volume <= 100);
+
+	volume_software_set = volume;
+	mixer_all_set_software_volume(volume);
+
+	return true;
+}
+
+static bool hardware_volume_change(unsigned volume)
+{
+	/* reset the cache */
+	last_hardware_volume = -1;
+
+	return mixer_all_set_volume(volume);
+}
+
+bool volume_level_change(unsigned volume)
+{
+	assert(volume <= 100);
+
+	volume_software_set = volume;
+
+	idle_add(IDLE_MIXER);
+
+	return hardware_volume_change(volume);
+}
+
+bool
+read_sw_volume_state(const char *line)
+{
+	char *end = nullptr;
+	long int sv;
+
+	if (!StringStartsWith(line, SW_VOLUME_STATE))
+		return false;
+
+	line += sizeof(SW_VOLUME_STATE) - 1;
+	sv = strtol(line, &end, 10);
+	if (*end == 0 && sv >= 0 && sv <= 100)
+		software_volume_change(sv);
+	else
+		FormatWarning(volume_domain,
+			      "Can't parse software volume: %s", line);
+	return true;
+}
+
+void save_sw_volume_state(FILE *fp)
+{
+	fprintf(fp, SW_VOLUME_STATE "%u\n", volume_software_set);
+}
+
+unsigned
+sw_volume_state_get_hash(void)
+{
+	return volume_software_set;
+}
diff --git a/src/mixer/Volume.hxx b/src/mixer/Volume.hxx
new file mode 100644
index 000000000..06d3551eb
--- /dev/null
+++ b/src/mixer/Volume.hxx
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2003-2014 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_VOLUME_HXX
+#define MPD_VOLUME_HXX
+
+#include "Compiler.h"
+
+#include <stdio.h>
+
+void volume_init(void);
+
+gcc_pure
+int volume_level_get(void);
+
+bool volume_level_change(unsigned volume);
+
+bool
+read_sw_volume_state(const char *line);
+
+void save_sw_volume_state(FILE *fp);
+
+/**
+ * Generates a hash number for the current state of the software
+ * volume control.  This is used by timer_save_state_file() to
+ * determine whether the state has changed and the state file should
+ * be saved.
+ */
+gcc_pure
+unsigned
+sw_volume_state_get_hash(void);
+
+#endif
diff --git a/src/mixer/AlsaMixerPlugin.cxx b/src/mixer/plugins/AlsaMixerPlugin.cxx
index 9d04ad98b..a15820fc7 100644
--- a/src/mixer/AlsaMixerPlugin.cxx
+++ b/src/mixer/plugins/AlsaMixerPlugin.cxx
@@ -18,7 +18,7 @@
  */
 
 #include "config.h"
-#include "MixerInternal.hxx"
+#include "mixer/MixerInternal.hxx"
 #include "output/OutputAPI.hxx"
 #include "GlobalEvents.hxx"
 #include "Main.hxx"
diff --git a/src/mixer/OssMixerPlugin.cxx b/src/mixer/plugins/OssMixerPlugin.cxx
index 4e116c2fb..095ace015 100644
--- a/src/mixer/OssMixerPlugin.cxx
+++ b/src/mixer/plugins/OssMixerPlugin.cxx
@@ -18,7 +18,7 @@
  */
 
 #include "config.h"
-#include "MixerInternal.hxx"
+#include "mixer/MixerInternal.hxx"
 #include "config/ConfigData.hxx"
 #include "system/fd_util.h"
 #include "util/ASCII.hxx"
diff --git a/src/mixer/PulseMixerPlugin.cxx b/src/mixer/plugins/PulseMixerPlugin.cxx
index a379cebae..4df88d06b 100644
--- a/src/mixer/PulseMixerPlugin.cxx
+++ b/src/mixer/plugins/PulseMixerPlugin.cxx
@@ -19,7 +19,7 @@
 
 #include "config.h"
 #include "PulseMixerPlugin.hxx"
-#include "MixerInternal.hxx"
+#include "mixer/MixerInternal.hxx"
 #include "output/plugins/PulseOutputPlugin.hxx"
 #include "GlobalEvents.hxx"
 #include "util/Error.hxx"
diff --git a/src/mixer/PulseMixerPlugin.hxx b/src/mixer/plugins/PulseMixerPlugin.hxx
index 993945e9b..993945e9b 100644
--- a/src/mixer/PulseMixerPlugin.hxx
+++ b/src/mixer/plugins/PulseMixerPlugin.hxx
diff --git a/src/mixer/RoarMixerPlugin.cxx b/src/mixer/plugins/RoarMixerPlugin.cxx
index 18f8c14f8..958688cd7 100644
--- a/src/mixer/RoarMixerPlugin.cxx
+++ b/src/mixer/plugins/RoarMixerPlugin.cxx
@@ -20,7 +20,7 @@
 
 
 #include "config.h"
-#include "MixerInternal.hxx"
+#include "mixer/MixerInternal.hxx"
 #include "output/plugins/RoarOutputPlugin.hxx"
 #include "Compiler.h"
 
diff --git a/src/mixer/SoftwareMixerPlugin.cxx b/src/mixer/plugins/SoftwareMixerPlugin.cxx
index a0de727af..67ddee1a4 100644
--- a/src/mixer/SoftwareMixerPlugin.cxx
+++ b/src/mixer/plugins/SoftwareMixerPlugin.cxx
@@ -19,7 +19,7 @@
 
 #include "config.h"
 #include "SoftwareMixerPlugin.hxx"
-#include "MixerInternal.hxx"
+#include "mixer/MixerInternal.hxx"
 #include "filter/FilterPlugin.hxx"
 #include "filter/FilterRegistry.hxx"
 #include "filter/FilterInternal.hxx"
diff --git a/src/mixer/SoftwareMixerPlugin.hxx b/src/mixer/plugins/SoftwareMixerPlugin.hxx
index 581d2ac17..581d2ac17 100644
--- a/src/mixer/SoftwareMixerPlugin.hxx
+++ b/src/mixer/plugins/SoftwareMixerPlugin.hxx
diff --git a/src/mixer/WinmmMixerPlugin.cxx b/src/mixer/plugins/WinmmMixerPlugin.cxx
index 6f10fd71b..093a026a9 100644
--- a/src/mixer/WinmmMixerPlugin.cxx
+++ b/src/mixer/plugins/WinmmMixerPlugin.cxx
@@ -18,7 +18,7 @@
  */
 
 #include "config.h"
-#include "MixerInternal.hxx"
+#include "mixer/MixerInternal.hxx"
 #include "output/OutputAPI.hxx"
 #include "output/plugins/WinmmOutputPlugin.hxx"
 #include "util/Error.hxx"