output/Interface: define a new struct AudioOutput

Hide struct FilteredAudioOutput from the plugins, preparing for hiding
MPD's core internals.

Makefile.am

@@ -1373,6 +1373,7 @@ OUTPUT_LIBS = \
 OUTPUT_API_SRC = \
 	src/output/Client.hxx \
 	src/output/OutputAPI.hxx \
+	src/output/Interface.hxx \
 	src/output/Filtered.cxx src/output/Filtered.hxx \
 	src/output/Wrapper.hxx \
 	src/output/Registry.cxx src/output/Registry.hxx \
@@ -2105,11 +2106,10 @@ test_run_convert_LDADD = \
 	libutil.a
 
 test_run_output_LDADD = $(MPD_LIBS) \
-	$(PCM_LIBS) \
 	$(OUTPUT_LIBS) \
 	$(ENCODER_LIBS) \
 	libmixer_plugins.a \
-	$(FILTER_LIBS) \
+	$(PCM_LIBS) \
 	$(TAG_LIBS) \
 	libconf.a \
 	libbasic.a \
@@ -2123,13 +2123,10 @@ test_run_output_LDADD = $(MPD_LIBS) \
 test_run_output_SOURCES = test/run_output.cxx \
 	src/Log.cxx src/LogBackend.cxx \
 	src/output/Domain.cxx \
-	src/output/Init.cxx src/output/Finish.cxx src/output/Registry.cxx \
+	src/output/Registry.cxx \
 	src/output/OutputPlugin.cxx \
 	src/mixer/MixerControl.cxx \
-	src/mixer/MixerType.cxx \
+	src/mixer/MixerType.cxx
-	src/filter/FilterPlugin.cxx \
-	src/filter/FilterConfig.cxx \
-	src/filter/Observer.cxx
 
 test_read_mixer_LDADD = \
 	libpcm.a \

src/output/Filtered.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "Filtered.hxx"
+#include "Interface.hxx"
 #include "OutputPlugin.hxx"
 #include "Domain.hxx"
 #include "Log.hxx"
@@ -31,22 +32,22 @@
 bool
 FilteredAudioOutput::SupportsEnableDisable() const noexcept
 {
-	assert((plugin.enable == nullptr) == (plugin.disable == nullptr));
+	assert((output->plugin.enable == nullptr) == (output->plugin.disable == nullptr));
 
-	return plugin.enable != nullptr;
+	return output->plugin.enable != nullptr;
 }
 
 bool
 FilteredAudioOutput::SupportsPause() const noexcept
 {
-	return plugin.pause != nullptr;
+	return output->plugin.pause != nullptr;
 }
 
 void
 FilteredAudioOutput::Enable()
 {
 	try {
-		ao_plugin_enable(*this);
+		ao_plugin_enable(*output);
 	} catch (const std::runtime_error &e) {
 		std::throw_with_nested(FormatRuntimeError("Failed to enable output %s",
 							  GetLogName()));
@@ -56,7 +57,7 @@ FilteredAudioOutput::Enable()
 void
 FilteredAudioOutput::Disable() noexcept
 {
-	ao_plugin_disable(*this);
+	ao_plugin_disable(*output);
 }
 
 void
@@ -76,7 +77,7 @@ FilteredAudioOutput::OpenOutputAndConvert(AudioFormat desired_audio_format)
 	out_audio_format = desired_audio_format;
 
 	try {
-		ao_plugin_open(*this, out_audio_format);
+		ao_plugin_open(*output, out_audio_format);
 	} catch (const std::runtime_error &e) {
 		std::throw_with_nested(FormatRuntimeError("Failed to open %s",
 							  GetLogName()));
@@ -90,7 +91,7 @@ FilteredAudioOutput::OpenOutputAndConvert(AudioFormat desired_audio_format)
 	try {
 		ConfigureConvertFilter();
 	} catch (const std::runtime_error &e) {
-		ao_plugin_close(*this);
+		ao_plugin_close(*output);
 
 		if (out_audio_format.format == SampleFormat::DSD) {
 			/* if the audio output supports DSD, but not
@@ -119,7 +120,7 @@ FilteredAudioOutput::CloseOutput(bool drain) noexcept
 	else
 		Cancel();
 
-	ao_plugin_close(*this);
+	ao_plugin_close(*output);
 }
 
 void
@@ -148,31 +149,31 @@ FilteredAudioOutput::Close(bool drain) noexcept
 std::chrono::steady_clock::duration
 FilteredAudioOutput::Delay() noexcept
 {
-	return ao_plugin_delay(*this);
+	return ao_plugin_delay(*output);
 }
 
 void
 FilteredAudioOutput::SendTag(const Tag &tag)
 {
-	ao_plugin_send_tag(*this, tag);
+	ao_plugin_send_tag(*output, tag);
 }
 
 size_t
 FilteredAudioOutput::Play(const void *data, size_t size)
 {
-	return ao_plugin_play(*this, data, size);
+	return ao_plugin_play(*output, data, size);
 }
 
 void
 FilteredAudioOutput::Drain()
 {
-	ao_plugin_drain(*this);
+	ao_plugin_drain(*output);
 }
 
 void
 FilteredAudioOutput::Cancel() noexcept
 {
-	ao_plugin_cancel(*this);
+	ao_plugin_cancel(*output);
 }
 
 void
@@ -185,7 +186,7 @@ bool
 FilteredAudioOutput::IteratePause() noexcept
 {
 	try {
-		return ao_plugin_pause(*this);
+		return ao_plugin_pause(*output);
 	} catch (const std::runtime_error &e) {
 		FormatError(e, "Failed to pause %s",
 			    GetLogName());

src/output/Filtered.hxx

@@ -33,7 +33,7 @@ class Mixer;
 class MixerListener;
 struct MusicChunk;
 struct ConfigBlock;
-struct AudioOutputPlugin;
+struct AudioOutput;
 struct ReplayGainConfig;
 struct Tag;
 
@@ -54,7 +54,7 @@ public:
 	/**
 	 * The plugin which implements this output device.
 	 */
-	const AudioOutputPlugin &plugin;
+	AudioOutput *const output;
 
 	/**
 	 * The #mixer object associated with this audio output device.
@@ -120,18 +120,11 @@ public:
 	/**
 	 * Throws #std::runtime_error on error.
 	 */
-	FilteredAudioOutput(const AudioOutputPlugin &_plugin,
+	FilteredAudioOutput(AudioOutput &_output,
 			    const ConfigBlock &block);
 
 	~FilteredAudioOutput();
 
-	/**
-	 * Plugins shall call this method if they require an
-	 * "audio_format" setting which evaluates
-	 * AudioFormat::IsFullyDefined().
-	 */
-	void NeedFullyDefinedAudioFormat();
-
 private:
 	void Configure(const ConfigBlock &block);
 

src/output/Finish.cxx

@@ -31,6 +31,8 @@ FilteredAudioOutput::~FilteredAudioOutput()
 	delete prepared_replay_gain_filter;
 	delete prepared_other_replay_gain_filter;
 	delete prepared_filter;
+
+	ao_plugin_finish(output);
 }
 
 void
@@ -43,5 +45,5 @@ FilteredAudioOutput::BeginDestroy() noexcept
 void
 FilteredAudioOutput::FinishDestroy() noexcept
 {
-	ao_plugin_finish(this);
+	ao_plugin_finish(output);
 }

src/output/Init.cxx

@@ -50,25 +50,21 @@
 #define AUDIO_OUTPUT_FORMAT	"format"
 #define AUDIO_FILTERS		"filters"
 
-FilteredAudioOutput::FilteredAudioOutput(const AudioOutputPlugin &_plugin,
+FilteredAudioOutput::FilteredAudioOutput(AudioOutput &_output,
 					 const ConfigBlock &block)
-	:plugin(_plugin)
+	:output(&_output)
 {
+#ifndef NDEBUG
+	const auto &plugin = output->plugin;
 	assert(plugin.finish != nullptr);
 	assert(plugin.open != nullptr);
 	assert(plugin.close != nullptr);
 	assert(plugin.play != nullptr);
+#endif
 
 	Configure(block);
 }
 
-void
-FilteredAudioOutput::NeedFullyDefinedAudioFormat()
-{
-	if (!config_audio_format.IsFullyDefined())
-		throw std::runtime_error("Need full audio format specification");
-}
-
 static const AudioOutputPlugin *
 audio_output_detect()
 {
@@ -176,7 +172,7 @@ FilteredAudioOutput::Configure(const ConfigBlock &block)
 	{
 		char buffer[64];
 		snprintf(buffer, sizeof(buffer), "\"%s\" (%s)",
-			 name, plugin.name);
+			 name, output->plugin.name);
 		log_name = buffer;
 	}
 
@@ -211,6 +207,9 @@ FilteredAudioOutput::Setup(EventLoop &event_loop,
 			   MixerListener &mixer_listener,
 			   const ConfigBlock &block)
 {
+	if (output->need_fully_defined_audio_format &&
+	    !config_audio_format.IsFullyDefined())
+		throw std::runtime_error("Need full audio format specification");
 
 	/* create the replay_gain filter */
 
@@ -234,7 +233,7 @@ FilteredAudioOutput::Setup(EventLoop &event_loop,
 
 	try {
 		mixer = audio_output_load_mixer(event_loop, *this, block,
-						plugin.mixer_plugin,
+						output->plugin.mixer_plugin,
 						*prepared_filter,
 						mixer_listener);
 	} catch (const std::runtime_error &e) {
@@ -295,13 +294,22 @@ audio_output_new(EventLoop &event_loop,
 	auto *ao = ao_plugin_init(event_loop, *plugin, block);
 	assert(ao != nullptr);
 
+	FilteredAudioOutput *f;
+
 	try {
-		ao->Setup(event_loop, replay_gain_config,
+		f = new FilteredAudioOutput(*ao, block);
-			  mixer_listener, block);
 	} catch (...) {
 		ao_plugin_finish(ao);
 		throw;
 	}
 
-	return ao;
+	try {
+		f->Setup(event_loop, replay_gain_config,
+			 mixer_listener, block);
+	} catch (...) {
+		delete f;
+		throw;
+	}
+
+	return f;
 }

src/output/Interface.hxx

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2003-2017 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_AUDIO_OUTPUT_INTERFACE_HXX
+#define MPD_AUDIO_OUTPUT_INTERFACE_HXX
+
+struct AudioOutputPlugin;
+struct FilteredAudioOutput;
+
+struct AudioOutput {
+	/**
+	 * The plugin which implements this output device.
+	 */
+	const AudioOutputPlugin &plugin;
+
+	FilteredAudioOutput *parent;
+
+	bool need_fully_defined_audio_format = false;
+
+	AudioOutput(const AudioOutputPlugin &_plugin)
+		:plugin(_plugin) {}
+
+	/**
+	 * Plugins shall call this method if they require an
+	 * "audio_format" setting which evaluates
+	 * AudioFormat::IsFullyDefined().
+	 */
+	void NeedFullyDefinedAudioFormat() {
+		need_fully_defined_audio_format = true;
+	}
+};
+
+#endif

src/output/OutputAPI.hxx

@@ -23,7 +23,7 @@
 // IWYU pragma: begin_exports
 
 #include "OutputPlugin.hxx"
-#include "Filtered.hxx"
+#include "Interface.hxx"
 #include "AudioFormat.hxx"
 #include "tag/Tag.hxx"
 #include "config/Block.hxx"

src/output/OutputPlugin.cxx

@@ -19,9 +19,11 @@
 
 #include "config.h"
 #include "OutputPlugin.hxx"
-#include "Filtered.hxx"
+#include "Interface.hxx"
 
-FilteredAudioOutput *
+#include <assert.h>
+
+AudioOutput *
 ao_plugin_init(EventLoop &event_loop,
 	       const AudioOutputPlugin &plugin,
 	       const ConfigBlock &block)
@@ -32,39 +34,39 @@ ao_plugin_init(EventLoop &event_loop,
 }
 
 void
-ao_plugin_finish(FilteredAudioOutput *ao) noexcept
+ao_plugin_finish(AudioOutput *ao) noexcept
 {
 	ao->plugin.finish(ao);
 }
 
 void
-ao_plugin_enable(FilteredAudioOutput &ao)
+ao_plugin_enable(AudioOutput &ao)
 {
 	if (ao.plugin.enable != nullptr)
 		ao.plugin.enable(&ao);
 }
 
 void
-ao_plugin_disable(FilteredAudioOutput &ao) noexcept
+ao_plugin_disable(AudioOutput &ao) noexcept
 {
 	if (ao.plugin.disable != nullptr)
 		ao.plugin.disable(&ao);
 }
 
 void
-ao_plugin_open(FilteredAudioOutput &ao, AudioFormat &audio_format)
+ao_plugin_open(AudioOutput &ao, AudioFormat &audio_format)
 {
 	ao.plugin.open(&ao, audio_format);
 }
 
 void
-ao_plugin_close(FilteredAudioOutput &ao) noexcept
+ao_plugin_close(AudioOutput &ao) noexcept
 {
 	ao.plugin.close(&ao);
 }
 
 std::chrono::steady_clock::duration
-ao_plugin_delay(FilteredAudioOutput &ao) noexcept
+ao_plugin_delay(AudioOutput &ao) noexcept
 {
 	return ao.plugin.delay != nullptr
 		? ao.plugin.delay(&ao)
@@ -72,34 +74,34 @@ ao_plugin_delay(FilteredAudioOutput &ao) noexcept
 }
 
 void
-ao_plugin_send_tag(FilteredAudioOutput &ao, const Tag &tag)
+ao_plugin_send_tag(AudioOutput &ao, const Tag &tag)
 {
 	if (ao.plugin.send_tag != nullptr)
 		ao.plugin.send_tag(&ao, tag);
 }
 
 size_t
-ao_plugin_play(FilteredAudioOutput &ao, const void *chunk, size_t size)
+ao_plugin_play(AudioOutput &ao, const void *chunk, size_t size)
 {
 	return ao.plugin.play(&ao, chunk, size);
 }
 
 void
-ao_plugin_drain(FilteredAudioOutput &ao)
+ao_plugin_drain(AudioOutput &ao)
 {
 	if (ao.plugin.drain != nullptr)
 		ao.plugin.drain(&ao);
 }
 
 void
-ao_plugin_cancel(FilteredAudioOutput &ao) noexcept
+ao_plugin_cancel(AudioOutput &ao) noexcept
 {
 	if (ao.plugin.cancel != nullptr)
 		ao.plugin.cancel(&ao);
 }
 
 bool
-ao_plugin_pause(FilteredAudioOutput &ao)
+ao_plugin_pause(AudioOutput &ao)
 {
 	return ao.plugin.pause != nullptr && ao.plugin.pause(&ao);
 }

src/output/OutputPlugin.hxx

@@ -29,7 +29,7 @@
 struct ConfigBlock;
 struct AudioFormat;
 struct Tag;
-struct FilteredAudioOutput;
+struct AudioOutput;
 struct MixerPlugin;
 class EventLoop;
 
@@ -57,12 +57,12 @@ struct AudioOutputPlugin {
 	 * @param param the configuration section, or nullptr if there is
 	 * no configuration
 	 */
-	FilteredAudioOutput *(*init)(EventLoop &event_loop, const ConfigBlock &block);
+	AudioOutput *(*init)(EventLoop &event_loop, const ConfigBlock &block);
 
 	/**
 	 * Free resources allocated by this device.
 	 */
-	void (*finish)(FilteredAudioOutput *data);
+	void (*finish)(AudioOutput *data);
 
 	/**
 	 * Enable the device.  This may allocate resources, preparing
@@ -70,13 +70,13 @@ struct AudioOutputPlugin {
 	 *
 	 * Throws #std::runtime_error on error.
 	 */
-	void (*enable)(FilteredAudioOutput *data);
+	void (*enable)(AudioOutput *data);
 
 	/**
 	 * Disables the device.  It is closed before this method is
 	 * called.
 	 */
-	void (*disable)(FilteredAudioOutput *data);
+	void (*disable)(AudioOutput *data);
 
 	/**
 	 * Really open the device.
@@ -86,12 +86,12 @@ struct AudioOutputPlugin {
 	 * @param audio_format the audio format in which data is going
 	 * to be delivered; may be modified by the plugin
 	 */
-	void (*open)(FilteredAudioOutput *data, AudioFormat &audio_format);
+	void (*open)(AudioOutput *data, AudioFormat &audio_format);
 
 	/**
 	 * Close the device.
 	 */
-	void (*close)(FilteredAudioOutput *data);
+	void (*close)(AudioOutput *data);
 
 	/**
 	 * Returns a positive number if the output thread shall further
@@ -102,13 +102,13 @@ struct AudioOutputPlugin {
 	 *
 	 * @return the duration to wait
 	 */
-	std::chrono::steady_clock::duration (*delay)(FilteredAudioOutput *data) noexcept;
+	std::chrono::steady_clock::duration (*delay)(AudioOutput *data) noexcept;
 
 	/**
 	 * Display metadata for the next chunk.  Optional method,
 	 * because not all devices can display metadata.
 	 */
-	void (*send_tag)(FilteredAudioOutput *data, const Tag &tag);
+	void (*send_tag)(AudioOutput *data, const Tag &tag);
 
 	/**
 	 * Play a chunk of audio data.
@@ -117,19 +117,19 @@ struct AudioOutputPlugin {
 	 *
 	 * @return the number of bytes played
 	 */
-	size_t (*play)(FilteredAudioOutput *data,
+	size_t (*play)(AudioOutput *data,
 		       const void *chunk, size_t size);
 
 	/**
 	 * Wait until the device has finished playing.
 	 */
-	void (*drain)(FilteredAudioOutput *data);
+	void (*drain)(AudioOutput *data);
 
 	/**
 	 * Try to cancel data which may still be in the device's
 	 * buffers.
 	 */
-	void (*cancel)(FilteredAudioOutput *data);
+	void (*cancel)(AudioOutput *data);
 
 	/**
 	 * Pause the device.  If supported, it may perform a special
@@ -142,7 +142,7 @@ struct AudioOutputPlugin {
 	 * @return false on error (output will be closed by caller),
 	 * true for continue to pause
 	 */
-	bool (*pause)(FilteredAudioOutput *data);
+	bool (*pause)(AudioOutput *data);
 
 	/**
 	 * The mixer plugin associated with this output plugin.  This
@@ -162,43 +162,43 @@ ao_plugin_test_default_device(const AudioOutputPlugin *plugin)
 }
 
 gcc_malloc
-FilteredAudioOutput *
+AudioOutput *
 ao_plugin_init(EventLoop &event_loop,
 	       const AudioOutputPlugin &plugin,
 	       const ConfigBlock &block);
 
 void
-ao_plugin_finish(FilteredAudioOutput *ao) noexcept;
+ao_plugin_finish(AudioOutput *ao) noexcept;
 
 void
-ao_plugin_enable(FilteredAudioOutput &ao);
+ao_plugin_enable(AudioOutput &ao);
 
 void
-ao_plugin_disable(FilteredAudioOutput &ao) noexcept;
+ao_plugin_disable(AudioOutput &ao) noexcept;
 
 void
-ao_plugin_open(FilteredAudioOutput &ao, AudioFormat &audio_format);
+ao_plugin_open(AudioOutput &ao, AudioFormat &audio_format);
 
 void
-ao_plugin_close(FilteredAudioOutput &ao) noexcept;
+ao_plugin_close(AudioOutput &ao) noexcept;
 
 gcc_pure
 std::chrono::steady_clock::duration
-ao_plugin_delay(FilteredAudioOutput &ao) noexcept;
+ao_plugin_delay(AudioOutput &ao) noexcept;
 
 void
-ao_plugin_send_tag(FilteredAudioOutput &ao, const Tag &tag);
+ao_plugin_send_tag(AudioOutput &ao, const Tag &tag);
 
 size_t
-ao_plugin_play(FilteredAudioOutput &ao, const void *chunk, size_t size);
+ao_plugin_play(AudioOutput &ao, const void *chunk, size_t size);
 
 void
-ao_plugin_drain(FilteredAudioOutput &ao);
+ao_plugin_drain(AudioOutput &ao);
 
 void
-ao_plugin_cancel(FilteredAudioOutput &ao) noexcept;
+ao_plugin_cancel(AudioOutput &ao) noexcept;
 
 bool
-ao_plugin_pause(FilteredAudioOutput &ao);
+ao_plugin_pause(AudioOutput &ao);
 
 #endif

src/output/Wrapper.hxx

@@ -20,78 +20,79 @@
 #ifndef MPD_OUTPUT_WRAPPER_HXX
 #define MPD_OUTPUT_WRAPPER_HXX
 
-#include "Filtered.hxx"
+#include "Interface.hxx"
 #include "util/Cast.hxx"
 
 #include <chrono>
 
 struct ConfigBlock;
+struct AudioFormat;
 struct Tag;
 
 template<class T>
 struct AudioOutputWrapper {
-	static T &Cast(FilteredAudioOutput &ao) {
+	static T &Cast(AudioOutput &ao) {
 		return ContainerCast(ao, &T::base);
 	}
 
-	static FilteredAudioOutput *Init(EventLoop &event_loop,
+	static AudioOutput *Init(EventLoop &event_loop,
 					 const ConfigBlock &block) {
 		T *t = T::Create(event_loop, block);
 		return &t->base;
 	}
 
-	static void Finish(FilteredAudioOutput *ao) {
+	static void Finish(AudioOutput *ao) {
 		T *t = &Cast(*ao);
 		delete t;
 	}
 
-	static void Enable(FilteredAudioOutput *ao) {
+	static void Enable(AudioOutput *ao) {
 		T &t = Cast(*ao);
 		t.Enable();
 	}
 
-	static void Disable(FilteredAudioOutput *ao) {
+	static void Disable(AudioOutput *ao) {
 		T &t = Cast(*ao);
 		t.Disable();
 	}
 
-	static void Open(FilteredAudioOutput *ao, AudioFormat &audio_format) {
+	static void Open(AudioOutput *ao, AudioFormat &audio_format) {
 		T &t = Cast(*ao);
 		t.Open(audio_format);
 	}
 
-	static void Close(FilteredAudioOutput *ao) {
+	static void Close(AudioOutput *ao) {
 		T &t = Cast(*ao);
 		t.Close();
 	}
 
 	gcc_pure
-	static std::chrono::steady_clock::duration Delay(FilteredAudioOutput *ao) noexcept {
+	static std::chrono::steady_clock::duration Delay(AudioOutput *ao) noexcept {
 		T &t = Cast(*ao);
 		return t.Delay();
 	}
 
-	static void SendTag(FilteredAudioOutput *ao, const Tag &tag) {
+	static void SendTag(AudioOutput *ao, const Tag &tag) {
 		T &t = Cast(*ao);
 		t.SendTag(tag);
 	}
 
-	static size_t Play(FilteredAudioOutput *ao, const void *chunk, size_t size) {
+	static size_t Play(AudioOutput *ao, const void *chunk, size_t size) {
 		T &t = Cast(*ao);
 		return t.Play(chunk, size);
 	}
 
-	static void Drain(FilteredAudioOutput *ao) {
+	static void Drain(AudioOutput *ao) {
 		T &t = Cast(*ao);
 		t.Drain();
 	}
 
-	static void Cancel(FilteredAudioOutput *ao) {
+	static void Cancel(AudioOutput *ao) {
 		T &t = Cast(*ao);
 		t.Cancel();
 	}
 
-	static bool Pause(FilteredAudioOutput *ao) {
+	static bool Pause(AudioOutput *ao) {
 		T &t = Cast(*ao);
 		return t.Pause();
 	}

src/output/plugins/AlsaOutputPlugin.cxx

@@ -64,7 +64,7 @@ class AlsaOutput final
 
 	friend struct AudioOutputWrapper<AlsaOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	Manual<PcmExport> pcm_export;
 
@@ -414,7 +414,7 @@ static constexpr Domain alsa_output_domain("alsa_output");
 
 AlsaOutput::AlsaOutput(EventLoop &loop, const ConfigBlock &block)
 	:MultiSocketMonitor(loop), DeferredMonitor(loop),
-	 base(alsa_output_plugin, block),
+	 base(alsa_output_plugin),
 	 device(block.GetBlockValue("device", "")),
 #ifdef ENABLE_DSD
 	 dop(block.GetBlockValue("dop", false) ||

src/output/plugins/AoOutputPlugin.cxx

@@ -40,7 +40,7 @@ static unsigned ao_output_ref;
 class AoOutput {
 	friend struct AudioOutputWrapper<AoOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const size_t write_size;
 	int driver;
@@ -95,7 +95,7 @@ MakeAoError()
 }
 
 AoOutput::AoOutput(const ConfigBlock &block)
-	:base(ao_output_plugin, block),
+	:base(ao_output_plugin),
 	 write_size(block.GetBlockValue("write_size", 1024u))
 {
 	if (ao_output_ref == 0) {

src/output/plugins/FifoOutputPlugin.cxx

@@ -37,7 +37,7 @@
 class FifoOutput {
 	friend struct AudioOutputWrapper<FifoOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const AllocatedPath path;
 	std::string path_utf8;
@@ -75,7 +75,7 @@ public:
 static constexpr Domain fifo_output_domain("fifo_output");
 
 FifoOutput::FifoOutput(const ConfigBlock &block)
-	:base(fifo_output_plugin, block),
+	:base(fifo_output_plugin),
 	 path(block.GetPath("path"))
 {
 	if (path.IsNull())

src/output/plugins/HaikuOutputPlugin.cxx

@@ -48,7 +48,7 @@ class HaikuOutput {
 	friend int haiku_output_get_volume(HaikuOutput &haiku);
 	friend bool haiku_output_set_volume(HaikuOutput &haiku, unsigned volume);
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	size_t write_size;
 
@@ -66,7 +66,7 @@ class HaikuOutput {
 
 public:
 	HaikuOutput(const ConfigBlock &block)
-		:base(haiku_output_plugin, block),
+		:base(haiku_output_plugin),
 		 /* XXX: by default we should let the MediaKit propose the buffer size */
 		 write_size(block.GetBlockValue("write_size", 4096u)) {}
 

src/output/plugins/JackOutputPlugin.cxx

@@ -43,7 +43,7 @@ static constexpr unsigned MAX_PORTS = 16;
 static constexpr size_t jack_sample_size = sizeof(jack_default_audio_sample_t);
 
 struct JackOutput {
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	/**
 	 * libjack options passed to jack_client_open().
@@ -162,7 +162,7 @@ parse_port_list(const char *source, std::string dest[])
 }
 
 JackOutput::JackOutput(const ConfigBlock &block)
-	:base(jack_output_plugin, block),
+	:base(jack_output_plugin),
 	 name(block.GetBlockValue("client_name", nullptr)),
 	 server_name(block.GetBlockValue("server_name", nullptr))
 {
@@ -443,7 +443,7 @@ JackOutput::Disable()
 	}
 }
 
-static FilteredAudioOutput *
+static AudioOutput *
 mpd_jack_init(EventLoop &, const ConfigBlock &block)
 {
 	jack_set_error_function(mpd_jack_error);

src/output/plugins/NullOutputPlugin.cxx

@@ -26,7 +26,7 @@
 class NullOutput {
 	friend struct AudioOutputWrapper<NullOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const bool sync;
 
@@ -34,7 +34,7 @@ class NullOutput {
 
 public:
 	NullOutput(const ConfigBlock &block)
-		:base(null_output_plugin, block),
+		:base(null_output_plugin),
 		 sync(block.GetBlockValue("sync", true)) {}
 
 	static NullOutput *Create(EventLoop &event_loop,

src/output/plugins/OSXOutputPlugin.cxx

@@ -36,7 +36,7 @@
 #include <memory>
 
 struct OSXOutput {
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	/* configuration settings */
 	OSType component_subtype;
@@ -80,7 +80,7 @@ osx_output_test_default_device(void)
 }
 
 OSXOutput::OSXOutput(const ConfigBlock &block)
-	:base(osx_output_plugin, block)
+	:base(osx_output_plugin)
 {
 	const char *device = block.GetBlockValue("device");
 
@@ -103,7 +103,7 @@ OSXOutput::OSXOutput(const ConfigBlock &block)
 	sync_sample_rate = block.GetBlockValue("sync_sample_rate", false);
 }
 
-static FilteredAudioOutput *
+static AudioOutput *
 osx_output_init(EventLoop &, const ConfigBlock &block)
 {
 	OSXOutput *oo = new OSXOutput(block);
@@ -128,7 +128,7 @@ osx_output_init(EventLoop &, const ConfigBlock &block)
 }
 
 static void
-osx_output_finish(FilteredAudioOutput *ao)
+osx_output_finish(AudioOutput *ao)
 {
 	OSXOutput *oo = (OSXOutput *)ao;
 
@@ -514,7 +514,7 @@ osx_render(void *vdata,
 }
 
 static void
-osx_output_enable(FilteredAudioOutput *ao)
+osx_output_enable(AudioOutput *ao)
 {
 	char errormsg[1024];
 	OSXOutput *oo = (OSXOutput *)ao;
@@ -550,7 +550,7 @@ osx_output_enable(FilteredAudioOutput *ao)
 }
 
 static void
-osx_output_disable(FilteredAudioOutput *ao)
+osx_output_disable(AudioOutput *ao)
 {
 	OSXOutput *oo = (OSXOutput *)ao;
 
@@ -562,7 +562,7 @@ osx_output_disable(FilteredAudioOutput *ao)
 }
 
 static void
-osx_output_close(FilteredAudioOutput *ao)
+osx_output_close(AudioOutput *ao)
 {
 	OSXOutput *od = (OSXOutput *)ao;
 
@@ -573,7 +573,7 @@ osx_output_close(FilteredAudioOutput *ao)
 }
 
 static void
-osx_output_open(FilteredAudioOutput *ao, AudioFormat &audio_format)
+osx_output_open(AudioOutput *ao, AudioFormat &audio_format)
 {
 	char errormsg[1024];
 	OSXOutput *od = (OSXOutput *)ao;
@@ -663,14 +663,14 @@ osx_output_open(FilteredAudioOutput *ao, AudioFormat &audio_format)
 }
 
 static size_t
-osx_output_play(FilteredAudioOutput *ao, const void *chunk, size_t size)
+osx_output_play(AudioOutput *ao, const void *chunk, size_t size)
 {
 	OSXOutput *od = (OSXOutput *)ao;
 	return od->ring_buffer->push((uint8_t *)chunk, size);
 }
 
 static std::chrono::steady_clock::duration
-osx_output_delay(FilteredAudioOutput *ao) noexcept
+osx_output_delay(AudioOutput *ao) noexcept
 {
 	OSXOutput *od = (OSXOutput *)ao;
 	return od->ring_buffer->write_available()

src/output/plugins/OpenALOutputPlugin.cxx

@@ -39,7 +39,7 @@ class OpenALOutput {
 	/* should be enough for buffer size = 2048 */
 	static constexpr unsigned NUM_BUFFERS = 16;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const char *device_name;
 	ALCdevice *device;
@@ -138,7 +138,7 @@ OpenALOutput::SetupContext()
 }
 
 OpenALOutput::OpenALOutput(const ConfigBlock &block)
-	:base(openal_output_plugin, block),
+	:base(openal_output_plugin),
 	 device_name(block.GetBlockValue("device"))
 {
 	if (device_name == nullptr)

src/output/plugins/OssOutputPlugin.cxx

@@ -63,7 +63,7 @@
 class OssOutput {
 	friend struct AudioOutputWrapper<OssOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 #ifdef AFMT_S24_PACKED
 	Manual<PcmExport> pcm_export;
@@ -85,8 +85,8 @@ class OssOutput {
 	int oss_format;
 
 public:
-	OssOutput(const ConfigBlock &block, const char *_device=nullptr)
+	explicit OssOutput(const char *_device=nullptr)
-		:base(oss_output_plugin, block),
+		:base(oss_output_plugin),
 		 fd(-1), device(_device) {}
 
 	static OssOutput *Create(EventLoop &event_loop,
@@ -192,11 +192,10 @@ oss_open_default()
 	int err[ARRAY_SIZE(default_devices)];
 	enum oss_stat ret[ARRAY_SIZE(default_devices)];
 
-	const ConfigBlock empty;
 	for (int i = ARRAY_SIZE(default_devices); --i >= 0; ) {
 		ret[i] = oss_stat_device(default_devices[i], &err[i]);
 		if (ret[i] == OSS_STAT_NO_ERROR)
-			return new OssOutput(empty, default_devices[i]);
+			return new OssOutput(default_devices[i]);
 	}
 
 	for (int i = ARRAY_SIZE(default_devices); --i >= 0; ) {
@@ -231,7 +230,7 @@ OssOutput::Create(EventLoop &, const ConfigBlock &block)
 {
 	const char *device = block.GetBlockValue("device");
 	if (device != nullptr)
-		return new OssOutput(block, device);
+		return new OssOutput(device);
 
 	return oss_open_default();
 }

src/output/plugins/PipeOutputPlugin.cxx

@@ -31,7 +31,7 @@
 class PipeOutput {
 	friend struct AudioOutputWrapper<PipeOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const std::string cmd;
 	FILE *fh;
@@ -52,7 +52,7 @@ public:
 };
 
 PipeOutput::PipeOutput(const ConfigBlock &block)
-	:base(pipe_output_plugin, block),
+	:base(pipe_output_plugin),
 	 cmd(block.GetBlockValue("command", ""))
 {
 	if (cmd.empty())

src/output/plugins/PulseOutputPlugin.cxx

@@ -47,7 +47,7 @@
 class PulseOutput {
 	friend struct AudioOutputWrapper<PulseOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const char *name;
 	const char *server;
@@ -179,7 +179,7 @@ private:
 };
 
 PulseOutput::PulseOutput(const ConfigBlock &block)
-	:base(pulse_output_plugin, block),
+	:base(pulse_output_plugin),
 	 name(block.GetBlockValue("name", "mpd_pulse")),
 	 server(block.GetBlockValue("server")),
 	 sink(block.GetBlockValue("sink"))

src/output/plugins/RecorderOutputPlugin.cxx

@@ -45,7 +45,7 @@ static constexpr Domain recorder_domain("recorder");
 class RecorderOutput {
 	friend struct AudioOutputWrapper<RecorderOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	/**
 	 * The configured encoder plugin.
@@ -114,7 +114,7 @@ private:
 };
 
 RecorderOutput::RecorderOutput(const ConfigBlock &block)
-	:base(recorder_output_plugin, block)
+	:base(recorder_output_plugin)
 {
 	/* read configuration */
 

src/output/plugins/RoarOutputPlugin.cxx

@@ -39,7 +39,7 @@
 class RoarOutput {
 	friend struct AudioOutputWrapper<RoarOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const std::string host, name;
 
@@ -54,7 +54,7 @@ class RoarOutput {
 public:
 	RoarOutput(const ConfigBlock &block);
 
-	operator FilteredAudioOutput *() {
+	operator AudioOutput *() {
 		return &base;
 	}
 
@@ -86,7 +86,7 @@ GetConfiguredRole(const ConfigBlock &block) noexcept
 }
 
 RoarOutput::RoarOutput(const ConfigBlock &block)
-	:base(roar_output_plugin, block),
+	:base(roar_output_plugin),
 	 host(block.GetBlockValue("server", "")),
 	 name(block.GetBlockValue("name", "MPD")),
 	 role(GetConfiguredRole(block))

src/output/plugins/ShoutOutputPlugin.cxx

@@ -40,7 +40,7 @@
 static constexpr unsigned DEFAULT_CONN_TIMEOUT = 2;
 
 struct ShoutOutput final {
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	shout_t *shout_conn;
 	shout_metadata_t *shout_meta;
@@ -113,7 +113,7 @@ ShoutSetAudioInfo(shout_t *shout_conn, const AudioFormat &audio_format)
 }
 
 ShoutOutput::ShoutOutput(const ConfigBlock &block)
-	:base(shout_output_plugin, block),
+	:base(shout_output_plugin),
 	 shout_conn(shout_new()),
 	 shout_meta(shout_metadata_new())
 {

src/output/plugins/SndioOutputPlugin.cxx

@@ -47,7 +47,7 @@ static constexpr Domain sndio_output_domain("sndio_output");
 
 class SndioOutput {
 	friend struct AudioOutputWrapper<SndioOutput>;
-	FilteredAudioOutput base;
+	AudioOutput base;
 	const char *const device;
 	const unsigned buffer_time; /* in ms */
 	struct sio_hdl *sio_hdl;
@@ -65,7 +65,7 @@ public:
 };
 
 SndioOutput::SndioOutput(const ConfigBlock &block)
-	:base(sndio_output_plugin, block),
+	:base(sndio_output_plugin),
 	 device(block.GetBlockValue("device", SIO_DEVANY)),
 	 buffer_time(block.GetBlockValue("buffer_time",
 					 MPD_SNDIO_BUFFER_TIME_MS))

src/output/plugins/SolarisOutputPlugin.cxx

@@ -53,7 +53,7 @@ struct audio_info {
 class SolarisOutput {
 	friend struct AudioOutputWrapper<SolarisOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	/* configuration */
 	const char *const device;
@@ -61,7 +61,7 @@ class SolarisOutput {
 	int fd;
 
 	explicit SolarisOutput(const ConfigBlock &block)
-		:base(solaris_output_plugin, block),
+		:base(solaris_output_plugin),
 		 device(block.GetBlockValue("device", "/dev/audio")) {}
 
 public:

src/output/plugins/WinmmOutputPlugin.cxx

@@ -42,7 +42,7 @@ struct WinmmBuffer {
 class WinmmOutput {
 	friend struct AudioOutputWrapper<WinmmOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	const UINT device_id;
 	HWAVEOUT handle;
@@ -148,7 +148,7 @@ get_device_id(const char *device_name)
 }
 
 WinmmOutput::WinmmOutput(const ConfigBlock &block)
-	:base(winmm_output_plugin, block),
+	:base(winmm_output_plugin),
 	 device_id(get_device_id(block.GetBlockValue("device")))
 {
 }

src/output/plugins/httpd/HttpdInternal.hxx

@@ -52,7 +52,7 @@ struct Tag;
 class HttpdOutput final : ServerSocket, DeferredMonitor {
 	friend struct AudioOutputWrapper<HttpdOutput>;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	/**
 	 * True if the audio output is open and accepts client
@@ -160,7 +160,7 @@ public:
 	static HttpdOutput *Create(EventLoop &event_loop,
 				   const ConfigBlock &block);
 
-	static constexpr HttpdOutput *Cast(FilteredAudioOutput *ao) {
+	static constexpr HttpdOutput *Cast(AudioOutput *ao) {
 		return &ContainerCast(*ao, &HttpdOutput::base);
 	}
 

src/output/plugins/httpd/HttpdOutputPlugin.cxx

@@ -51,7 +51,7 @@ const Domain httpd_output_domain("httpd_output");
 inline
 HttpdOutput::HttpdOutput(EventLoop &_loop, const ConfigBlock &block)
 	:ServerSocket(_loop), DeferredMonitor(_loop),
-	 base(httpd_output_plugin, block),
+	 base(httpd_output_plugin),
 	 encoder(nullptr), unflushed_input(0),
 	 metadata(nullptr)
 {

src/output/plugins/sles/SlesOutputPlugin.cxx

@@ -43,7 +43,7 @@ class SlesOutput {
 	static constexpr unsigned N_BUFFERS = 3;
 	static constexpr size_t BUFFER_SIZE = 65536;
 
-	FilteredAudioOutput base;
+	AudioOutput base;
 
 	SLES::Object engine_object, mix_object, play_object;
 	SLES::Play play;
@@ -87,9 +87,9 @@ class SlesOutput {
 	uint8_t buffers[N_BUFFERS][BUFFER_SIZE];
 
 public:
-	SlesOutput(const ConfigBlock &block);
+	SlesOutput();
 
-	operator FilteredAudioOutput *() {
+	operator AudioOutput *() {
 		return &base;
 	}
 
@@ -129,8 +129,8 @@ private:
 
 static constexpr Domain sles_domain("sles");
 
-SlesOutput::SlesOutput(const ConfigBlock &block)
+SlesOutput::SlesOutput()
-	:base(sles_output_plugin, block)
+	:base(sles_output_plugin)
 {
 }
 
@@ -416,9 +416,9 @@ sles_test_default_device()
 }
 
 inline SlesOutput *
-SlesOutput::Create(EventLoop &, const ConfigBlock &block)
+SlesOutput::Create(EventLoop &, const ConfigBlock &)
 {
-	return new SlesOutput(block);
+	return new SlesOutput();
 }
 
 typedef AudioOutputWrapper<SlesOutput> Wrapper;

test/run_output.cxx

@@ -18,19 +18,17 @@
  */
 
 #include "config.h"
-#include "output/Filtered.hxx"
+#include "output/Interface.hxx"
+#include "output/Registry.hxx"
 #include "output/OutputPlugin.hxx"
 #include "config/Param.hxx"
 #include "config/ConfigGlobal.hxx"
 #include "config/ConfigOption.hxx"
-#include "Idle.hxx"
+#include "config/Block.hxx"
-#include "Main.hxx"
 #include "event/Thread.hxx"
 #include "fs/Path.hxx"
 #include "AudioParser.hxx"
-#include "ReplayGainConfig.hxx"
 #include "pcm/PcmConvert.hxx"
-#include "filter/FilterRegistry.hxx"
 #include "util/StringBuffer.hxx"
 #include "util/RuntimeError.hxx"
 #include "util/ScopeExit.hxx"
@@ -42,28 +40,29 @@
 #include <stdlib.h>
 #include <stdio.h>
 
-const FilterPlugin *
+static AudioOutput *
-filter_plugin_by_name(gcc_unused const char *name) noexcept
-{
-	assert(false);
-	return NULL;
-}
-
-static FilteredAudioOutput *
 load_audio_output(EventLoop &event_loop, const char *name)
 {
-	const auto *param = config_find_block(ConfigBlockOption::AUDIO_OUTPUT,
+	const auto *block = config_find_block(ConfigBlockOption::AUDIO_OUTPUT,
 					      "name", name);
-	if (param == NULL)
+	if (block == nullptr)
-		throw FormatRuntimeError("No such configured audio output: %s\n",
+		throw FormatRuntimeError("No such configured audio output: %s",
 					 name);
 
-	return audio_output_new(event_loop, ReplayGainConfig(), *param,
+	const char *plugin_name = block->GetBlockValue("type");
-				*(MixerListener *)nullptr);
+	if (plugin_name == nullptr)
+		throw std::runtime_error("Missing \"type\" configuration");
+
+	const auto *plugin = AudioOutputPlugin_get(plugin_name);
+	if (plugin == nullptr)
+		throw FormatRuntimeError("No such audio output plugin: %s",
+					 plugin_name);
+
+	return ao_plugin_init(event_loop, *plugin, *block);
 }
 
 static void
-run_output(FilteredAudioOutput &ao, AudioFormat audio_format)
+run_output(AudioOutput &ao, AudioFormat audio_format)
 {
 	/* open the audio output */
 
@@ -140,8 +139,7 @@ try {
 
 	/* cleanup and exit */
 
-	ao->BeginDestroy();
+	ao_plugin_finish(ao);
-	ao->FinishDestroy();
 
 	config_global_finish();