Use AL_SOFT_direct_channels_remix extension for non-positional stereo sounds

builtin/settingtypes.txt

@@ -1870,6 +1870,11 @@ texture_min_size (Base texture size) int 64 1 32768
 #    Systems with a low-end GPU (or no GPU) would benefit from smaller values.
 client_mesh_chunk (Client Mesh Chunksize) int 1 1 16
 
+[**Sound]
+#    Comma-separated list of AL and ALC extensions that should not be used.
+#    Useful for testing. See al_extensions.[h,cpp] for details.
+sound_extensions_blacklist (Sound Extensions Blacklist) string
+
 [**Font]
 
 font_bold (Font bold by default) bool false

src/client/CMakeLists.txt

@@ -2,6 +2,7 @@ set(sound_SRCS ${CMAKE_CURRENT_SOURCE_DIR}/sound.cpp)
 
 if(USE_SOUND)
 	set(sound_SRCS ${sound_SRCS}
+		${CMAKE_CURRENT_SOURCE_DIR}/sound/al_extensions.cpp
 		${CMAKE_CURRENT_SOURCE_DIR}/sound/al_helpers.cpp
 		${CMAKE_CURRENT_SOURCE_DIR}/sound/ogg_file.cpp
 		${CMAKE_CURRENT_SOURCE_DIR}/sound/playing_sound.cpp

src/client/sound/al_extensions.cpp

@@ -0,0 +1,58 @@
+/*
+Minetest
+Copyright (C) 2023 DS
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; ifnot, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "al_extensions.h"
+
+#include "settings.h"
+#include "util/string.h"
+#include <unordered_set>
+
+namespace sound {
+
+ALExtensions::ALExtensions(const ALCdevice *deviceHandle [[maybe_unused]])
+{
+	auto blacklist_vec = str_split(g_settings->get("sound_extensions_blacklist"), ',');
+	for (auto &s : blacklist_vec) {
+		s = trim(s);
+	}
+	std::unordered_set<std::string> blacklist;
+	blacklist.insert(blacklist_vec.begin(), blacklist_vec.end());
+
+	{
+		constexpr const char *ext_name = "AL_SOFT_direct_channels_remix";
+		bool blacklisted = blacklist.find(ext_name) != blacklist.end();
+		if (blacklisted)
+			infostream << "ALExtensions: Blacklisted: " << ext_name << std::endl;
+#ifndef AL_SOFT_direct_channels_remix
+		infostream << "ALExtensions: Not compiled with: " << ext_name << std::endl;
+#else
+		bool found = alIsExtensionPresent(ext_name);
+		if (found)
+			infostream << "ALExtensions: Found: " << ext_name << std::endl;
+		else
+			infostream << "ALExtensions: Not found: " << ext_name << std::endl;
+
+		if (found && !blacklisted) {
+			have_ext_AL_SOFT_direct_channels_remix = true;
+		}
+#endif
+	}
+}
+
+}

src/client/sound/al_extensions.h

@@ -0,0 +1,38 @@
+/*
+Minetest
+Copyright (C) 2023 DS
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; ifnot, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include "al_helpers.h"
+
+namespace sound {
+
+/**
+ * Struct for AL and ALC extensions
+ */
+struct ALExtensions
+{
+	explicit ALExtensions(const ALCdevice *deviceHandle [[maybe_unused]]);
+
+#ifdef AL_SOFT_direct_channels_remix
+	bool have_ext_AL_SOFT_direct_channels_remix = false;
+#endif
+};
+
+}

src/client/sound/playing_sound.cpp

@@ -24,6 +24,7 @@ with this program; ifnot, write to the Free Software Foundation, Inc.,
 
 #include "playing_sound.h"
 
+#include "al_extensions.h"
 #include "debug.h"
 #include <cassert>
 #include <cmath>
@@ -32,7 +33,8 @@ namespace sound {
 
 PlayingSound::PlayingSound(ALuint source_id, std::shared_ptr<ISoundDataOpen> data,
 		bool loop, f32 volume, f32 pitch, f32 start_time,
-		const std::optional<std::pair<v3f, v3f>> &pos_vel_opt)
+		const std::optional<std::pair<v3f, v3f>> &pos_vel_opt,
+		const ALExtensions &exts [[maybe_unused]])
 	: m_source_id(source_id), m_data(std::move(data)), m_looping(loop),
 	m_is_positional(pos_vel_opt.has_value())
 {
@@ -113,6 +115,15 @@ PlayingSound::PlayingSound(ALuint source_id, std::shared_ptr<ISoundDataOpen> dat
 		alSource3f(m_source_id, AL_POSITION, 0.0f, 0.0f, 0.0f);
 		alSource3f(m_source_id, AL_VELOCITY, 0.0f, 0.0f, 0.0f);
 		warn_if_al_error("PlayingSound::PlayingSound at making position-less");
+
+#ifdef AL_SOFT_direct_channels_remix
+		// Play directly on stereo output channels if possible. Improves sound quality.
+		if (exts.have_ext_AL_SOFT_direct_channels_remix
+				&& m_data->m_decode_info.is_stereo) {
+			alSourcei(m_source_id, AL_DIRECT_CHANNELS_SOFT, AL_REMIX_UNMATCHED_SOFT);
+			warn_if_al_error("PlayingSound::PlayingSound at setting AL_DIRECT_CHANNELS_SOFT");
+		}
+#endif
 	}
 	setGain(volume);
 	setPitch(pitch);

src/client/sound/playing_sound.h

@@ -25,6 +25,7 @@ with this program; ifnot, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include "sound_data.h"
+namespace sound { struct ALExtensions; }
 
 namespace sound {
 
@@ -51,7 +52,8 @@ class PlayingSound final
 public:
 	PlayingSound(ALuint source_id, std::shared_ptr<ISoundDataOpen> data, bool loop,
 			f32 volume, f32 pitch, f32 start_time,
-			const std::optional<std::pair<v3f, v3f>> &pos_vel_opt);
+			const std::optional<std::pair<v3f, v3f>> &pos_vel_opt,
+			const ALExtensions &exts [[maybe_unused]]);
 
 	~PlayingSound() noexcept
 	{

src/client/sound/sound_manager.cpp

@@ -181,7 +181,7 @@ std::shared_ptr<PlayingSound> OpenALSoundManager::createPlayingSound(
 	}
 
 	auto sound = std::make_shared<PlayingSound>(source_id, std::move(lsnd), loop,
-			volume, pitch, start_time, pos_vel_opt);
+			volume, pitch, start_time, pos_vel_opt, m_exts);
 
 	sound->play();
 
@@ -271,7 +271,8 @@ OpenALSoundManager::OpenALSoundManager(SoundManagerSingleton *smg,
 	Thread("OpenALSoundManager"),
 	m_fallback_path_provider(std::move(fallback_path_provider)),
 	m_device(smg->m_device.get()),
-	m_context(smg->m_context.get())
+	m_context(smg->m_context.get()),
+	m_exts(m_device)
 {
 	SANITY_CHECK(!!m_fallback_path_provider);
 

src/client/sound/sound_manager.h

@@ -25,6 +25,7 @@ with this program; ifnot, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include "playing_sound.h"
+#include "al_extensions.h"
 #include "sound_constants.h"
 #include "sound_manager_messages.h"
 #include "../sound.h"
@@ -51,8 +52,10 @@ class OpenALSoundManager final : public Thread
 private:
 	std::unique_ptr<SoundFallbackPathProvider> m_fallback_path_provider;
 
-	ALCdevice *m_device;
-	ALCcontext *m_context;
+	ALCdevice *const m_device;
+	ALCcontext *const m_context;
+
+	const ALExtensions m_exts;
 
 	// time in seconds until which removeDeadSounds will be called again
 	f32 m_time_until_dead_removal = REMOVE_DEAD_SOUNDS_INTERVAL;

src/defaultsettings.cpp

@@ -42,6 +42,7 @@ void set_default_settings()
 	settings->setDefault("sound_volume", "0.8");
 	settings->setDefault("sound_volume_unfocused", "0.3");
 	settings->setDefault("mute_sound", "false");
+	settings->setDefault("sound_extensions_blacklist", "");
 	settings->setDefault("enable_mesh_cache", "false");
 	settings->setDefault("mesh_generation_interval", "0");
 	settings->setDefault("mesh_generation_threads", "0");