Use decibel scaling for volume control

osu.Framework/Audio/AudioManager.cs

@@ -90,23 +90,20 @@ public class AudioManager : AudioCollectionManager<AudioComponent>
         /// </summary>
         public readonly Bindable<string> AudioDevice = new Bindable<string>();
 
+        /// <summary>
+        /// Volume of all audio game-wide.
+        /// </summary>
+        public new readonly BindableVolume Volume;
+
         /// <summary>
         /// Volume of all samples played game-wide.
         /// </summary>
-        public readonly BindableDouble VolumeSample = new BindableDouble(1)
-        {
-            MinValue = 0,
-            MaxValue = 1
-        };
+        public readonly BindableVolume VolumeSample = new BindableVolume();
 
         /// <summary>
         /// Volume of all tracks played game-wide.
         /// </summary>
-        public readonly BindableDouble VolumeTrack = new BindableDouble(1)
-        {
-            MinValue = 0,
-            MaxValue = 1
-        };
+        public readonly BindableVolume VolumeTrack = new BindableVolume();
 
         /// <summary>
         /// Whether a global mixer is being used for audio routing.
@@ -179,19 +176,21 @@ public AudioManager(AudioThread audioThread, ResourceStore<byte[]> trackStore, R
             AddItem(TrackMixer = createAudioMixer(null, nameof(TrackMixer)));
             AddItem(SampleMixer = createAudioMixer(null, nameof(SampleMixer)));
 
+            Volume = new BindableVolume(base.Volume);
+
             globalTrackStore = new Lazy<TrackStore>(() =>
             {
                 var store = new TrackStore(trackStore, TrackMixer);
                 AddItem(store);
-                store.AddAdjustment(AdjustableProperty.Volume, VolumeTrack);
+                store.AddAdjustment(AdjustableProperty.Volume, VolumeTrack.Real);
                 return store;
             });
 
             globalSampleStore = new Lazy<SampleStore>(() =>
             {
                 var store = new SampleStore(sampleStore, SampleMixer);
                 AddItem(store);
-                store.AddAdjustment(AdjustableProperty.Volume, VolumeSample);
+                store.AddAdjustment(AdjustableProperty.Volume, VolumeSample.Real);
                 return store;
             });
 

osu.Framework/Audio/BindableVolume.cs

@@ -0,0 +1,47 @@
+// Copyright (c) ppy Pty Ltd <[email protected]>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Framework.Bindables;
+
+namespace osu.Framework.Audio
+{
+    public class BindableVolume
+    {
+        public const double MIN = -60;
+        public const double STEP = 0.5;
+
+        private const double ln_ten = 2.302585092994045684017991454684364208;
+        private const double k = ln_ten / 20;
+
+        public readonly BindableNumber<double> Real;
+        public readonly BindableNumber<double> Scaled = new BindableNumber<double>(1)
+        {
+            MinValue = MIN,
+            MaxValue = 0,
+            Precision = STEP,
+        };
+
+        private double scaledToReal(double x) => x <= MIN ? 0 : Math.Exp(k * x);
+
+        private double realToScaled(double x) => x <= 0 ? MIN : Math.Log(x) / k;
+
+        public BindableVolume(BindableNumber<double>? real = null)
+        {
+            Real = real ?? new BindableNumber<double>(1) { MinValue = 0, MaxValue = 1 };
+            Scaled.BindValueChanged(x => Real.Value = scaledToReal(x.NewValue));
+        }
+
+        public double Value
+        {
+            get => Real.Value;
+            set => Scaled.Value = realToScaled(value);
+        }
+
+        public void Scale()
+        {
+            Scaled.Value = realToScaled(Real.Value);
+            Scaled.Default = realToScaled(Real.Default);
+        }
+    }
+}

osu.Framework/Configuration/FrameworkConfigManager.cs

@@ -32,9 +32,9 @@ protected override void InitialiseDefaults()
             SetDefault(FrameworkSetting.WindowedPositionY, 0.5, -0.5, 1.5);
             SetDefault(FrameworkSetting.LastDisplayDevice, DisplayIndex.Default);
             SetDefault(FrameworkSetting.AudioDevice, string.Empty);
-            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);
+            SetDefault(FrameworkSetting.VolumeUniversal, 1.0, 0.0, 1.0);
+            SetDefault(FrameworkSetting.VolumeMusic, 1.0, 0.0, 1.0);
+            SetDefault(FrameworkSetting.VolumeEffect, 1.0, 0.0, 1.0);
             SetDefault(FrameworkSetting.HardwareVideoDecoder, HardwareVideoDecoder.Any);
             SetDefault(FrameworkSetting.SizeFullscreen, new Size(9999, 9999), new Size(320, 240));
             SetDefault(FrameworkSetting.MinimiseOnFocusLossInFullscreen, RuntimeInfo.IsDesktop);

osu.Framework/Game.cs

@@ -173,9 +173,13 @@ private void load(FrameworkConfigManager config)
 
             // attach our bindables to the audio subsystem.
             config.BindWith(FrameworkSetting.AudioDevice, Audio.AudioDevice);
-            config.BindWith(FrameworkSetting.VolumeUniversal, Audio.Volume);
-            config.BindWith(FrameworkSetting.VolumeEffect, Audio.VolumeSample);
-            config.BindWith(FrameworkSetting.VolumeMusic, Audio.VolumeTrack);
+            config.BindWith(FrameworkSetting.VolumeUniversal, Audio.Volume.Real);
+            config.BindWith(FrameworkSetting.VolumeEffect, Audio.VolumeSample.Real);
+            config.BindWith(FrameworkSetting.VolumeMusic, Audio.VolumeTrack.Real);
+
+            Audio.Volume.Scale();
+            Audio.VolumeSample.Scale();
+            Audio.VolumeTrack.Scale();
 
             Shaders = new ShaderManager(Host.Renderer, new NamespacedResourceStore<byte[]>(Resources, @"Shaders"));
             dependencies.Cache(Shaders);