[3.x] Add ability to mute AudioServer.

doc/classes/AudioServer.xml

@@ -182,6 +182,12 @@
 				If [code]true[/code], the bus at index [code]bus_idx[/code] is in solo mode.
 			</description>
 		</method>
+		<method name="is_enabled" qualifiers="const">
+			<return type="bool" />
+			<description>
+				If [code]false[/code], the audio server is disabled / muted.
+			</description>
+		</method>
 		<method name="lock">
 			<return type="void" />
 			<description>
@@ -276,6 +282,13 @@
 				Sets the volume of the bus at index [code]bus_idx[/code] to [code]volume_db[/code].
 			</description>
 		</method>
+		<method name="set_enabled">
+			<return type="void" />
+			<argument index="0" name="enabled" type="bool" />
+			<description>
+				Allows disabling / muting the audio server. As well as muting, this will minimize audio CPU usage.
+			</description>
+		</method>
 		<method name="swap_bus_effects">
 			<return type="void" />
 			<argument index="0" name="bus_idx" type="int" />

doc/classes/ProjectSettings.xml

@@ -290,6 +290,19 @@
 		<member name="audio/mix_rate.web" type="int" setter="" getter="" default="0">
 			Safer override for [member audio/mix_rate] in the Web platform. Here [code]0[/code] means "let the browser choose" (since some browsers do not like forcing the mix rate).
 		</member>
+		<member name="audio/muting/mute_driver" type="bool" setter="" getter="" default="false">
+			If [code]true[/code], the current audio driver will be disabled, minimizing CPU usage. This will affect both audio output and input.
+			[b]Note:[/b] The driver can be enabled and disabled at runtime using the [method AudioServer.set_enabled] function.
+		</member>
+		<member name="audio/muting/mute_on_focus_loss" type="bool" setter="" getter="" default="false">
+			If [code]true[/code], the current audio driver will be automatically disabled when the application loses focus, and re-enabled when the application regains focus.
+		</member>
+		<member name="audio/muting/mute_on_pause" type="bool" setter="" getter="" default="true">
+			If [code]true[/code], the current audio driver will be automatically disabled when the application is paused by the OS, and re-enabled when the application is resumed.
+		</member>
+		<member name="audio/muting/mute_on_silence" type="bool" setter="" getter="" default="false">
+			If [code]true[/code], the current audio driver will be automatically disabled after a period of silence is detected, and re-enabled when audio attempts to play.
+		</member>
 		<member name="audio/output_latency" type="int" setter="" getter="" default="15">
 			Specifies the preferred output latency in milliseconds for audio. Lower values will result in lower audio latency at the cost of increased CPU usage. Low values may result in audible cracking on slower hardware.
 			Audio output latency may be constrained by the host operating system and audio hardware drivers. If the host can not provide the specified audio output latency then Godot will attempt to use the nearest latency allowed by the host. As such you should always use [method AudioServer.get_output_latency] to determine the actual audio output latency.

editor/editor_node.cpp

@@ -6048,6 +6048,12 @@ EditorNode::EditorNode() {
 	EDITOR_DEF("interface/editor/update_continuously", false);
 	EDITOR_DEF("interface/editor/update_vital_only", false);
 	EDITOR_DEF("interface/editor/localize_settings", true);
+
+	AudioServer::get_singleton()->set_enabled(!EDITOR_DEF_RST("interface/audio/muting/mute_driver", false));
+	AudioDriverManager::set_mute_sensitivity(AudioDriverManager::MUTE_FLAG_SILENCE, EDITOR_DEF_RST("interface/audio/muting/mute_on_silence", true));
+	AudioDriverManager::set_mute_sensitivity(AudioDriverManager::MUTE_FLAG_PAUSED, EDITOR_DEF_RST("interface/audio/muting/mute_on_pause", true));
+	AudioDriverManager::set_mute_sensitivity(AudioDriverManager::MUTE_FLAG_FOCUS_LOSS, EDITOR_DEF_RST("interface/audio/muting/mute_on_focus_loss", true));
+
 	EDITOR_DEF_RST("interface/scene_tabs/restore_scenes_on_load", false);
 	EDITOR_DEF_RST("interface/scene_tabs/show_thumbnail_on_hover", true);
 	EDITOR_DEF_RST("interface/inspector/default_property_name_style", EditorPropertyNameProcessor::STYLE_CAPITALIZED);

scene/main/scene_tree.cpp

@@ -49,6 +49,7 @@
 #include "scene/resources/mesh.h"
 #include "scene/resources/packed_scene.h"
 #include "scene/scene_string_names.h"
+#include "servers/audio_server.h"
 #include "servers/navigation_server.h"
 #include "servers/physics_2d_server.h"
 #include "servers/physics_server.h"
@@ -819,6 +820,8 @@ void SceneTree::_notification(int p_notification) {
 		} break;
 
 		case NOTIFICATION_WM_FOCUS_IN: {
+			AudioDriverManager::set_mute_flag(AudioDriverManager::MUTE_FLAG_FOCUS_LOSS, false);
+
 			InputDefault *id = Object::cast_to<InputDefault>(Input::get_singleton());
 			if (id) {
 				id->ensure_touch_mouse_raised();
@@ -839,16 +842,25 @@ void SceneTree::_notification(int p_notification) {
 			get_root()->propagate_notification(p_notification);
 
 		} break;
+		case NOTIFICATION_WM_FOCUS_OUT: {
+			AudioDriverManager::set_mute_flag(AudioDriverManager::MUTE_FLAG_FOCUS_LOSS, true);
+			get_root()->propagate_notification(p_notification);
+		} break;
+		case NOTIFICATION_APP_PAUSED: {
+			AudioDriverManager::set_mute_flag(AudioDriverManager::MUTE_FLAG_PAUSED, true);
+			get_root()->propagate_notification(p_notification);
+		} break;
+		case NOTIFICATION_APP_RESUMED: {
+			AudioDriverManager::set_mute_flag(AudioDriverManager::MUTE_FLAG_PAUSED, false);
+			get_root()->propagate_notification(p_notification);
+		} break;
 
 		case NOTIFICATION_OS_MEMORY_WARNING:
 		case NOTIFICATION_OS_IME_UPDATE:
 		case NOTIFICATION_WM_MOUSE_ENTER:
 		case NOTIFICATION_WM_MOUSE_EXIT:
-		case NOTIFICATION_WM_FOCUS_OUT:
 		case NOTIFICATION_WM_ABOUT:
-		case NOTIFICATION_CRASH:
-		case NOTIFICATION_APP_RESUMED:
-		case NOTIFICATION_APP_PAUSED: {
+		case NOTIFICATION_CRASH: {
 			get_root()->propagate_notification(p_notification);
 		} break;
 

servers/audio/audio_driver_dummy.cpp

@@ -98,6 +98,7 @@ void AudioDriverDummy::finish() {
 
 	if (samples_in) {
 		memdelete_arr(samples_in);
+		samples_in = nullptr;
 	};
 };