Enforce minimum gameplay sample volume of 5%

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableHoldNote.cs

@@ -108,7 +108,11 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
                     RelativeSizeAxes = Axes.X
                 },
                 tailContainer = new Container<DrawableHoldNoteTail> { RelativeSizeAxes = Axes.Both },
-                slidingSample = new PausableSkinnableSound { Looping = true }
+                slidingSample = new PausableSkinnableSound
+                {
+                    Looping = true,
+                    MinimumSampleVolume = MINIMUM_SAMPLE_VOLUME,
+                }
             });
 
             maskedContents.AddRange(new[]

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

@@ -107,7 +107,11 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
                 headContainer = new Container<DrawableSliderHead> { RelativeSizeAxes = Axes.Both },
                 OverlayElementContainer = new Container { RelativeSizeAxes = Axes.Both, },
                 Ball,
-                slidingSample = new PausableSkinnableSound { Looping = true }
+                slidingSample = new PausableSkinnableSound
+                {
+                    Looping = true,
+                    MinimumSampleVolume = MINIMUM_SAMPLE_VOLUME,
+                }
             });
 
             PositionBindable.BindValueChanged(_ => Position = HitObject.StackedPosition);

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSpinner.cs

@@ -99,6 +99,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
                 spinningSample = new PausableSkinnableSound
                 {
                     Volume = { Value = 0 },
+                    MinimumSampleVolume = MINIMUM_SAMPLE_VOLUME,
                     Looping = true,
                     Frequency = { Value = spinning_sample_initial_frequency }
                 }

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -159,6 +159,26 @@ namespace osu.Game.Rulesets.Objects.Drawables
         /// </summary>
         internal bool IsInitialized;
 
+        /// <summary>
+        /// The minimum allowable volume for sample playback.
+        /// <see cref="Samples"/> quieter than that will be forcibly played at this volume instead.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// Drawable hitobjects adding their own custom samples, or other sample playback sources
+        /// (i.e. <see cref="GameplaySampleTriggerSource"/>) must enforce this themselves.
+        /// </para>
+        /// <para>
+        /// This sample volume floor is present in stable, although it is set at 8% rather than 5%.
+        /// See: https://github.com/peppy/osu-stable-reference/blob/3ea48705eb67172c430371dcfc8a16a002ed0d3d/osu!/Audio/AudioEngine.cs#L1070,
+        /// https://github.com/peppy/osu-stable-reference/blob/3ea48705eb67172c430371dcfc8a16a002ed0d3d/osu!/Audio/AudioEngine.cs#L1404-L1405.
+        /// The reason why it is 5% here is that the 8% cap was enforced in a silent manner
+        /// (i.e. the minimum selectable volume in the editor was 5%, but it would be played at 8% anyways),
+        /// which is confusing and arbitrary, so we're just doing 5% here at the cost of sacrificing strict parity.
+        /// </para>
+        /// </remarks>
+        public const int MINIMUM_SAMPLE_VOLUME = 5;
+
         /// <summary>
         /// Creates a new <see cref="DrawableHitObject"/>.
         /// </summary>
@@ -181,7 +201,10 @@ namespace osu.Game.Rulesets.Objects.Drawables
             comboColourBrightness.BindTo(gameplaySettings.ComboColourNormalisationAmount);
 
             // Explicit non-virtual function call in case a DrawableHitObject overrides AddInternal.
-            base.AddInternal(Samples = new PausableSkinnableSound());
+            base.AddInternal(Samples = new PausableSkinnableSound
+            {
+                MinimumSampleVolume = MINIMUM_SAMPLE_VOLUME
+            });
 
             CurrentSkin = skinSource;
             CurrentSkin.SourceChanged += skinSourceChanged;

osu.Game/Rulesets/UI/GameplaySampleTriggerSource.cs

@@ -7,6 +7,7 @@ using osu.Framework.Allocation;
 using osu.Framework.Graphics.Containers;
 using osu.Game.Audio;
 using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Screens.Play;
 using osu.Game.Skinning;
@@ -45,7 +46,10 @@ namespace osu.Game.Rulesets.UI
                 Child = hitSounds = new Container<SkinnableSound>
                 {
                     Name = "concurrent sample pool",
-                    ChildrenEnumerable = Enumerable.Range(0, max_concurrent_hitsounds).Select(_ => new PausableSkinnableSound())
+                    ChildrenEnumerable = Enumerable.Range(0, max_concurrent_hitsounds).Select(_ => new PausableSkinnableSound
+                    {
+                        MinimumSampleVolume = DrawableHitObject.MINIMUM_SAMPLE_VOLUME
+                    })
                 }
             };
         }

osu.Game/Skinning/SkinnableSound.cs

@@ -20,6 +20,12 @@ namespace osu.Game.Skinning
     /// </summary>
     public partial class SkinnableSound : SkinReloadableDrawable, IAdjustableAudioComponent
     {
+        /// <summary>
+        /// The minimum allowable volume for <see cref="Samples"/>.
+        /// <see cref="Samples"/> that specify a lower <see cref="ISampleInfo.Volume"/> will be forcibly pulled up to this volume.
+        /// </summary>
+        public int MinimumSampleVolume { get; set; }
+
         public override bool RemoveWhenNotAlive => false;
         public override bool RemoveCompletedTransforms => false;
 
@@ -156,7 +162,7 @@ namespace osu.Game.Skinning
             {
                 var sample = samplePool?.GetPooledSample(s) ?? new PoolableSkinnableSample(s);
                 sample.Looping = Looping;
-                sample.Volume.Value = s.Volume / 100.0;
+                sample.Volume.Value = Math.Max(s.Volume, MinimumSampleVolume) / 100.0;
 
                 samplesContainer.Add(sample);
             }