Expose experimental WASAPI support as a user config toggle

osu.Framework/Audio/AudioManager.cs

@@ -96,6 +96,13 @@ namespace osu.Framework.Audio
         /// </summary>
         public readonly Bindable<string> AudioDevice = new Bindable<string>();
 
+        /// <summary>
+        /// Whether to use experimental WASAPI initialisation on windows.
+        /// This generally results in lower audio latency, but also changes the audio synchronisation from
+        /// historical expectations, meaning users / application will have to account for different offsets.
+        /// </summary>
+        public readonly BindableBool UseExperimentalWasapi = new BindableBool();
+
         /// <summary>
         /// Volume of all samples played game-wide.
         /// </summary>
@@ -176,6 +183,7 @@ namespace osu.Framework.Audio
             thread.RegisterManager(this);
 
             AudioDevice.ValueChanged += _ => onDeviceChanged();
+            UseExperimentalWasapi.ValueChanged += _ => onDeviceChanged();
             GlobalMixerHandle.ValueChanged += handle =>
             {
                 onDeviceChanged();
@@ -430,10 +438,16 @@ namespace osu.Framework.Audio
             // See https://www.un4seen.com/forum/?topic=19601 for more information.
             Bass.Configure((ManagedBass.Configuration)70, false);
 
-            if (!thread.InitDevice(device))
-                return false;
+            if (UseExperimentalWasapi.Value)
+            {
+                if (thread.InitDevice(device, true))
+                    return true;
 
-            return true;
+                Logger.Log($"BASS device {device} failed to initialise with experimental WASAPI, disabling", level: LogLevel.Error);
+                UseExperimentalWasapi.Value = false;
+            }
+
+            return thread.InitDevice(device, false);
         }
 
         private void syncAudioDevices()

osu.Framework/Configuration/FrameworkConfigManager.cs

@@ -32,6 +32,7 @@ namespace osu.Framework.Configuration
             SetDefault(FrameworkSetting.WindowedPositionY, 0.5, -0.5, 1.5);
             SetDefault(FrameworkSetting.LastDisplayDevice, DisplayIndex.Default);
             SetDefault(FrameworkSetting.AudioDevice, string.Empty);
+            SetDefault(FrameworkSetting.AudioUseExperimentalWasapi, false);
             SetDefault(FrameworkSetting.VolumeUniversal, 1.0, 0.0, 1.0, 0.01);
             SetDefault(FrameworkSetting.VolumeMusic, 1.0, 0.0, 1.0, 0.01);
             SetDefault(FrameworkSetting.VolumeEffect, 1.0, 0.0, 1.0, 0.01);
@@ -79,6 +80,7 @@ namespace osu.Framework.Configuration
         ShowLogOverlay,
 
         AudioDevice,
+        AudioUseExperimentalWasapi,
         VolumeUniversal,
         VolumeEffect,
         VolumeMusic,

osu.Framework/FrameworkEnvironment.cs

@@ -21,7 +21,6 @@ namespace osu.Framework
         public static bool NoStructuredBuffers { get; }
         public static string? DeferredRendererEventsOutputPath { get; }
         public static bool UseSDL3 { get; }
-        public static bool UseWasapi { get; }
 
         /// <summary>
         /// Whether non-SSL requests should be allowed. Debug only. Defaults to disabled.
@@ -56,8 +55,6 @@ namespace osu.Framework
 
             // Desktop has many issues, see https://github.com/ppy/osu-framework/issues/6540.
             UseSDL3 = RuntimeInfo.IsMobile || (parseBool(Environment.GetEnvironmentVariable("OSU_SDL3")) ?? false);
-
-            UseWasapi = parseBool(Environment.GetEnvironmentVariable("OSU_AUDIO_WASAPI_EXPERIMENTAL")) ?? false;
         }
 
         private static bool? parseBool(string? value)

osu.Framework/Game.cs

@@ -196,6 +196,7 @@ namespace osu.Framework
 
             // attach our bindables to the audio subsystem.
             config.BindWith(FrameworkSetting.AudioDevice, Audio.AudioDevice);
+            config.BindWith(FrameworkSetting.AudioUseExperimentalWasapi, Audio.UseExperimentalWasapi);
             config.BindWith(FrameworkSetting.VolumeUniversal, Audio.Volume);
             config.BindWith(FrameworkSetting.VolumeEffect, Audio.VolumeSample);
             config.BindWith(FrameworkSetting.VolumeMusic, Audio.VolumeTrack);

osu.Framework/Threading/AudioThread.cs

@@ -130,7 +130,7 @@ namespace osu.Framework.Threading
         /// </summary>
         private readonly Bindable<int?> globalMixerHandle = new Bindable<int?>();
 
-        internal bool InitDevice(int deviceId)
+        internal bool InitDevice(int deviceId, bool useExperimentalWasapi)
         {
             Debug.Assert(ThreadSafety.IsAudioThread);
             Trace.Assert(deviceId != -1); // The real device ID should always be used, as the -1 device has special cases which are hard to work with.
@@ -139,9 +139,7 @@ namespace osu.Framework.Threading
             if (!Bass.Init(deviceId, Flags: (DeviceInitFlags)128)) // 128 == BASS_DEVICE_REINIT
                 return false;
 
-            // That this has not been mass-tested since https://github.com/ppy/osu-framework/pull/6651 and probably needs to be.
-            // Currently envvar gated for users to test at their own discretion.
-            if (FrameworkEnvironment.UseWasapi)
+            if (useExperimentalWasapi)
                 attemptWasapiInitialisation();
 
             initialised_devices.Add(deviceId);
@@ -182,10 +180,10 @@ namespace osu.Framework.Threading
             }
         }
 
-        private void attemptWasapiInitialisation()
+        private bool attemptWasapiInitialisation()
         {
             if (RuntimeInfo.OS != RuntimeInfo.Platform.Windows)
-                return;
+                return false;
 
             Logger.Log("Attempting local BassWasapi initialisation");
 
@@ -219,10 +217,10 @@ namespace osu.Framework.Threading
 
             // To keep things in a sane state let's only keep one device initialised via wasapi.
             freeWasapi();
-            initWasapi(wasapiDevice);
+            return initWasapi(wasapiDevice);
         }
 
-        private void initWasapi(int wasapiDevice)
+        private bool initWasapi(int wasapiDevice)
         {
             // This is intentionally initialised inline and stored to a field.
             // If we don't do this, it gets GC'd away.
@@ -246,13 +244,14 @@ namespace osu.Framework.Threading
             Logger.Log($"Initialising BassWasapi for device {wasapiDevice}...{(initialised ? "success!" : "FAILED")}");
 
             if (!initialised)
-                return;
+                return false;
 
             BassWasapi.GetInfo(out var wasapiInfo);
             globalMixerHandle.Value = BassMix.CreateMixerStream(wasapiInfo.Frequency, wasapiInfo.Channels, BassFlags.MixerNonStop | BassFlags.Decode | BassFlags.Float);
             BassWasapi.Start();
 
             BassWasapi.SetNotify(wasapiNotifyProcedure);
+            return true;
         }
 
         private void freeWasapi()