Fix multiplayer spectator not getting gameplay adjustments applied

osu.Game/Screens/OnlinePlay/Multiplayer/Spectate/MultiSpectatorPlayer.cs

@@ -53,6 +53,15 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         }
 
         protected override GameplayClockContainer CreateGameplayClockContainer(WorkingBeatmap beatmap, double gameplayStart)
-            => new GameplayClockContainer(spectatorPlayerClock);
+        {
+            var gameplayClockContainer = new GameplayClockContainer(spectatorPlayerClock);
+
+            // Directionality is important, as BindAdjustments is... not actually a bidirectional bind...
+            // We want to ensure that any adjustments applied by the Player instance are applied to the SpectatorPlayerClock
+            // so they can be consumed by the spectator screen (and applied to the master clock / track).
+            spectatorPlayerClock.GameplayAdjustments.BindAdjustments(gameplayClockContainer.GameplayAdjustments);
+
+            return gameplayClockContainer;
+        }
     }
 }

osu.Game/Screens/OnlinePlay/Multiplayer/Spectate/MultiSpectatorScreen.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Linq;
 using osu.Framework.Allocation;
+using osu.Framework.Audio;
 using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -43,6 +44,8 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         [Resolved]
         private MultiplayerClient multiplayerClient { get; set; } = null!;
 
+        private AudioAdjustments? boundAdjustments;
+
         private readonly PlayerArea[] instances;
         private MasterGameplayClockContainer masterClockContainer = null!;
         private SpectatorSyncManager syncManager = null!;
@@ -157,6 +160,9 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             base.LoadComplete();
 
             masterClockContainer.Reset();
+
+            // Start with adjustments from the first player to keep a sane state.
+            bindAudioAdjustments(instances.First());
         }
 
         protected override void Update()
@@ -169,11 +175,24 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
                                               .OrderBy(i => Math.Abs(i.SpectatorPlayerClock.CurrentTime - syncManager.CurrentMasterTime))
                                               .FirstOrDefault();
 
+                // Only bind adjustments if there's actually a valid source, else just use the previous ones to ensure no sudden changes to audio.
+                if (currentAudioSource != null)
+                    bindAudioAdjustments(currentAudioSource);
+
                 foreach (var instance in instances)
                     instance.Mute = instance != currentAudioSource;
             }
         }
 
+        private void bindAudioAdjustments(PlayerArea first)
+        {
+            if (boundAdjustments != null)
+                masterClockContainer.GameplayAdjustments.UnbindAdjustments(boundAdjustments);
+
+            boundAdjustments = first.SpectatorPlayerClock.GameplayAdjustments;
+            masterClockContainer.GameplayAdjustments.BindAdjustments(boundAdjustments);
+        }
+
         private bool isCandidateAudioSource(SpectatorPlayerClock? clock)
             => clock?.IsRunning == true && !clock.IsCatchingUp && !clock.WaitingOnFrames;
 

osu.Game/Screens/OnlinePlay/Multiplayer/Spectate/SpectatorPlayerClock.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using osu.Framework.Audio;
 using osu.Framework.Timing;
 using osu.Game.Screens.Play;
 
@@ -19,6 +20,8 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
 
         private readonly GameplayClockContainer masterClock;
 
+        public readonly AudioAdjustments GameplayAdjustments = new AudioAdjustments();
+
         public double CurrentTime { get; private set; }
 
         /// <summary>