Merge branch 'master' into no-gameplay-clock-gameplay-offset

osu.Game.Tests/OnlinePlay/TestSceneCatchUpSyncManager.cs

@@ -19,20 +19,20 @@ namespace osu.Game.Tests.OnlinePlay
     public class TestSceneCatchUpSyncManager : OsuTestScene
     {
         private GameplayClockContainer master;
-        private CatchUpSyncManager syncManager;
+        private SpectatorSyncManager syncManager;
 
-        private Dictionary<ISpectatorPlayerClock, int> clocksById;
+        private Dictionary<SpectatorPlayerClock, int> clocksById;
-        private ISpectatorPlayerClock player1;
+        private SpectatorPlayerClock player1;
-        private ISpectatorPlayerClock player2;
+        private SpectatorPlayerClock player2;
 
         [SetUp]
         public void Setup()
         {
-            syncManager = new CatchUpSyncManager(master = new GameplayClockContainer(new TestManualClock()));
+            syncManager = new SpectatorSyncManager(master = new GameplayClockContainer(new TestManualClock()));
             player1 = syncManager.CreateManagedClock();
             player2 = syncManager.CreateManagedClock();
 
-            clocksById = new Dictionary<ISpectatorPlayerClock, int>
+            clocksById = new Dictionary<SpectatorPlayerClock, int>
             {
                 { player1, 1 },
                 { player2, 2 }
@@ -64,7 +64,7 @@ namespace osu.Game.Tests.OnlinePlay
         public void TestReadyPlayersStartWhenReadyForMaximumDelayTime()
         {
             setWaiting(() => player1, false);
-            AddWaitStep($"wait {CatchUpSyncManager.MAXIMUM_START_DELAY} milliseconds", (int)Math.Ceiling(CatchUpSyncManager.MAXIMUM_START_DELAY / TimePerAction));
+            AddWaitStep($"wait {SpectatorSyncManager.MAXIMUM_START_DELAY} milliseconds", (int)Math.Ceiling(SpectatorSyncManager.MAXIMUM_START_DELAY / TimePerAction));
             assertPlayerClockState(() => player1, true);
             assertPlayerClockState(() => player2, false);
         }
@@ -74,7 +74,7 @@ namespace osu.Game.Tests.OnlinePlay
         {
             setAllWaiting(false);
 
-            setMasterTime(CatchUpSyncManager.SYNC_TARGET + 1);
+            setMasterTime(SpectatorSyncManager.SYNC_TARGET + 1);
             assertCatchingUp(() => player1, false);
         }
 
@@ -83,7 +83,7 @@ namespace osu.Game.Tests.OnlinePlay
         {
             setAllWaiting(false);
 
-            setMasterTime(CatchUpSyncManager.MAX_SYNC_OFFSET + 1);
+            setMasterTime(SpectatorSyncManager.MAX_SYNC_OFFSET + 1);
             assertCatchingUp(() => player1, true);
             assertCatchingUp(() => player2, true);
         }
@@ -93,8 +93,8 @@ namespace osu.Game.Tests.OnlinePlay
         {
             setAllWaiting(false);
 
-            setMasterTime(CatchUpSyncManager.MAX_SYNC_OFFSET + 1);
+            setMasterTime(SpectatorSyncManager.MAX_SYNC_OFFSET + 1);
-            setPlayerClockTime(() => player1, CatchUpSyncManager.SYNC_TARGET + 1);
+            setPlayerClockTime(() => player1, SpectatorSyncManager.SYNC_TARGET + 1);
             assertCatchingUp(() => player1, true);
         }
 
@@ -103,8 +103,8 @@ namespace osu.Game.Tests.OnlinePlay
         {
             setAllWaiting(false);
 
-            setMasterTime(CatchUpSyncManager.MAX_SYNC_OFFSET + 2);
+            setMasterTime(SpectatorSyncManager.MAX_SYNC_OFFSET + 2);
-            setPlayerClockTime(() => player1, CatchUpSyncManager.SYNC_TARGET);
+            setPlayerClockTime(() => player1, SpectatorSyncManager.SYNC_TARGET);
             assertCatchingUp(() => player1, false);
             assertCatchingUp(() => player2, true);
         }
@@ -114,7 +114,7 @@ namespace osu.Game.Tests.OnlinePlay
         {
             setAllWaiting(false);
 
-            setPlayerClockTime(() => player1, -CatchUpSyncManager.SYNC_TARGET);
+            setPlayerClockTime(() => player1, -SpectatorSyncManager.SYNC_TARGET);
             assertCatchingUp(() => player1, false);
             assertPlayerClockState(() => player1, true);
         }
@@ -124,7 +124,7 @@ namespace osu.Game.Tests.OnlinePlay
         {
             setAllWaiting(false);
 
-            setPlayerClockTime(() => player1, -CatchUpSyncManager.SYNC_TARGET - 1);
+            setPlayerClockTime(() => player1, -SpectatorSyncManager.SYNC_TARGET - 1);
 
             // This is a silent catchup, where IsCatchingUp = false but IsRunning = false also.
             assertCatchingUp(() => player1, false);
@@ -145,13 +145,13 @@ namespace osu.Game.Tests.OnlinePlay
             assertPlayerClockState(() => player1, false);
         }
 
-        private void setWaiting(Func<ISpectatorPlayerClock> playerClock, bool waiting)
+        private void setWaiting(Func<SpectatorPlayerClock> playerClock, bool waiting)
-            => AddStep($"set player clock {clocksById[playerClock()]} waiting = {waiting}", () => playerClock().WaitingOnFrames.Value = waiting);
+            => AddStep($"set player clock {clocksById[playerClock()]} waiting = {waiting}", () => playerClock().WaitingOnFrames = waiting);
 
         private void setAllWaiting(bool waiting) => AddStep($"set all player clocks waiting = {waiting}", () =>
         {
-            player1.WaitingOnFrames.Value = waiting;
+            player1.WaitingOnFrames = waiting;
-            player2.WaitingOnFrames.Value = waiting;
+            player2.WaitingOnFrames = waiting;
         });
 
         private void setMasterTime(double time)
@@ -160,13 +160,13 @@ namespace osu.Game.Tests.OnlinePlay
         /// <summary>
         /// clock.Time = master.Time - offsetFromMaster
         /// </summary>
-        private void setPlayerClockTime(Func<ISpectatorPlayerClock> playerClock, double offsetFromMaster)
+        private void setPlayerClockTime(Func<SpectatorPlayerClock> playerClock, double offsetFromMaster)
             => AddStep($"set player clock {clocksById[playerClock()]} = master - {offsetFromMaster}", () => playerClock().Seek(master.CurrentTime - offsetFromMaster));
 
-        private void assertCatchingUp(Func<ISpectatorPlayerClock> playerClock, bool catchingUp) =>
+        private void assertCatchingUp(Func<SpectatorPlayerClock> playerClock, bool catchingUp) =>
             AddAssert($"player clock {clocksById[playerClock()]} {(catchingUp ? "is" : "is not")} catching up", () => playerClock().IsCatchingUp == catchingUp);
 
-        private void assertPlayerClockState(Func<ISpectatorPlayerClock> playerClock, bool running)
+        private void assertPlayerClockState(Func<SpectatorPlayerClock> playerClock, bool running)
             => AddAssert($"player clock {clocksById[playerClock()]} {(running ? "is" : "is not")} running", () => playerClock().IsRunning == running);
 
         private class TestManualClock : ManualClock, IAdjustableClock

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiSpectatorScreen.cs

@@ -202,7 +202,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
             checkPausedInstant(PLAYER_2_ID, true);
 
             // Wait for the start delay seconds...
-            AddWaitStep("wait maximum start delay seconds", (int)(CatchUpSyncManager.MAXIMUM_START_DELAY / TimePerAction));
+            AddWaitStep("wait maximum start delay seconds", (int)(SpectatorSyncManager.MAXIMUM_START_DELAY / TimePerAction));
 
             // Player 1 should start playing by itself, player 2 should remain paused.
             checkPausedInstant(PLAYER_1_ID, false);
@@ -318,7 +318,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
             loadSpectateScreen();
             sendFrames(PLAYER_1_ID, 300);
 
-            AddWaitStep("wait maximum start delay seconds", (int)(CatchUpSyncManager.MAXIMUM_START_DELAY / TimePerAction));
+            AddWaitStep("wait maximum start delay seconds", (int)(SpectatorSyncManager.MAXIMUM_START_DELAY / TimePerAction));
             checkPaused(PLAYER_1_ID, false);
 
             sendFrames(PLAYER_2_ID, 300);

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

@@ -1,37 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-using osu.Framework.Bindables;
-using osu.Framework.Timing;
-
-namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
-{
-    /// <summary>
-    /// A clock which is used by <see cref="MultiSpectatorPlayer"/>s and managed by an <see cref="ISyncManager"/>.
-    /// </summary>
-    public interface ISpectatorPlayerClock : IFrameBasedClock, IAdjustableClock
-    {
-        /// <summary>
-        /// Starts this <see cref="ISpectatorPlayerClock"/>.
-        /// </summary>
-        new void Start();
-
-        /// <summary>
-        /// Stops this <see cref="ISpectatorPlayerClock"/>.
-        /// </summary>
-        new void Stop();
-
-        /// <summary>
-        /// Whether this clock is waiting on frames to continue playback.
-        /// </summary>
-        Bindable<bool> WaitingOnFrames { get; }
-
-        /// <summary>
-        /// Whether this clock is behind the master clock and running at a higher rate to catch up to it.
-        /// </summary>
-        /// <remarks>
-        /// Of note, this will be false if this clock is *ahead* of the master clock.
-        /// </remarks>
-        bool IsCatchingUp { get; set; }
-    }
-}

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

@@ -1,42 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-using System;
-using osu.Framework.Bindables;
-using osu.Game.Screens.Play;
-
-namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
-{
-    /// <summary>
-    /// Manages the synchronisation between one or more <see cref="ISpectatorPlayerClock"/>s in relation to a master clock.
-    /// </summary>
-    public interface ISyncManager
-    {
-        /// <summary>
-        /// An event which is invoked when gameplay is ready to start.
-        /// </summary>
-        event Action? ReadyToStart;
-
-        /// <summary>
-        /// The master clock which player clocks should synchronise to.
-        /// </summary>
-        GameplayClockContainer MasterClock { get; }
-
-        /// <summary>
-        /// An event which is invoked when the state of <see cref="MasterClock"/> is changed.
-        /// </summary>
-        IBindable<MasterClockState> MasterState { get; }
-
-        /// <summary>
-        /// Create a new managed <see cref="ISpectatorPlayerClock"/>.
-        /// </summary>
-        /// <returns>The newly created <see cref="ISpectatorPlayerClock"/>.</returns>
-        ISpectatorPlayerClock CreateManagedClock();
-
-        /// <summary>
-        /// Removes an <see cref="ISpectatorPlayerClock"/>, stopping it from being managed by this <see cref="ISyncManager"/>.
-        /// </summary>
-        /// <param name="clock">The <see cref="ISpectatorPlayerClock"/> to remove.</param>
-        void RemoveManagedClock(ISpectatorPlayerClock clock);
-    }
-}

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

@@ -2,7 +2,6 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Framework.Allocation;
-using osu.Framework.Bindables;
 using osu.Game.Beatmaps;
 using osu.Game.Scoring;
 using osu.Game.Screens.Play;
@@ -14,15 +13,14 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
     /// </summary>
     public class MultiSpectatorPlayer : SpectatorPlayer
     {
-        private readonly Bindable<bool> waitingOnFrames = new Bindable<bool>(true);
+        private readonly SpectatorPlayerClock spectatorPlayerClock;
-        private readonly ISpectatorPlayerClock spectatorPlayerClock;
 
         /// <summary>
         /// Creates a new <see cref="MultiSpectatorPlayer"/>.
         /// </summary>
         /// <param name="score">The score containing the player's replay.</param>
         /// <param name="spectatorPlayerClock">The clock controlling the gameplay running state.</param>
-        public MultiSpectatorPlayer(Score score, ISpectatorPlayerClock spectatorPlayerClock)
+        public MultiSpectatorPlayer(Score score, SpectatorPlayerClock spectatorPlayerClock)
             : base(score, new PlayerConfiguration { AllowUserInteraction = false })
         {
             this.spectatorPlayerClock = spectatorPlayerClock;
@@ -31,8 +29,6 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         [BackgroundDependencyLoader]
         private void load()
         {
-            spectatorPlayerClock.WaitingOnFrames.BindTo(waitingOnFrames);
-
             HUDOverlay.PlayerSettingsOverlay.Expire();
             HUDOverlay.HoldToQuit.Expire();
         }
@@ -40,9 +36,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         protected override void Update()
         {
             // The player clock's running state is controlled externally, but the local pausing state needs to be updated to start/stop gameplay.
-            CatchUpSpectatorPlayerClock catchUpClock = (CatchUpSpectatorPlayerClock)GameplayClockContainer.SourceClock;
+            if (GameplayClockContainer.SourceClock.IsRunning)
-
-            if (catchUpClock.IsRunning)
                 GameplayClockContainer.Start();
             else
                 GameplayClockContainer.Stop();
@@ -55,7 +49,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             base.UpdateAfterChildren();
 
             // This is required because the frame stable clock is set to WaitingOnFrames = false for one frame.
-            waitingOnFrames.Value = DrawableRuleset.FrameStableClock.WaitingOnFrames.Value || Score.Replay.Frames.Count == 0;
+            spectatorPlayerClock.WaitingOnFrames = DrawableRuleset.FrameStableClock.WaitingOnFrames.Value || Score.Replay.Frames.Count == 0;
         }
 
         protected override GameplayClockContainer CreateGameplayClockContainer(WorkingBeatmap beatmap, double gameplayStart)

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

@@ -4,12 +4,9 @@
 using System;
 using System.Linq;
 using osu.Framework.Allocation;
-using osu.Framework.Bindables;
 using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
-using osu.Framework.Logging;
-using osu.Game.Beatmaps;
 using osu.Game.Graphics;
 using osu.Game.Online.Multiplayer;
 using osu.Game.Online.Rooms;
@@ -48,11 +45,10 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
 
         private readonly PlayerArea[] instances;
         private MasterGameplayClockContainer masterClockContainer = null!;
-        private ISyncManager syncManager = null!;
+        private SpectatorSyncManager syncManager = null!;
         private PlayerGrid grid = null!;
         private MultiSpectatorLeaderboard leaderboard = null!;
         private PlayerArea? currentAudioSource;
-        private bool canStartMasterClock;
 
         private readonly Room room;
         private readonly MultiplayerRoomUser[] users;
@@ -77,50 +73,54 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             FillFlowContainer leaderboardFlow;
             Container scoreDisplayContainer;
 
-            masterClockContainer = CreateMasterGameplayClockContainer(Beatmap.Value);
+            InternalChildren = new Drawable[]
-
-            InternalChildren = new[]
             {
-                (Drawable)(syncManager = new CatchUpSyncManager(masterClockContainer)),
+                masterClockContainer = new MasterGameplayClockContainer(Beatmap.Value, 0)
-                masterClockContainer.WithChild(new GridContainer
                 {
-                    RelativeSizeAxes = Axes.Both,
+                    Child = new GridContainer
-                    RowDimensions = new[] { new Dimension(GridSizeMode.AutoSize) },
-                    Content = new[]
                     {
-                        new Drawable[]
+                        RelativeSizeAxes = Axes.Both,
+                        RowDimensions = new[] { new Dimension(GridSizeMode.AutoSize) },
+                        Content = new[]
                         {
-                            scoreDisplayContainer = new Container
+                            new Drawable[]
                             {
-                                RelativeSizeAxes = Axes.X,
+                                scoreDisplayContainer = new Container
-                                AutoSizeAxes = Axes.Y
-                            },
-                        },
-                        new Drawable[]
-                        {
-                            new GridContainer
-                            {
-                                RelativeSizeAxes = Axes.Both,
-                                ColumnDimensions = new[] { new Dimension(GridSizeMode.AutoSize) },
-                                Content = new[]
                                 {
-                                    new Drawable[]
+                                    RelativeSizeAxes = Axes.X,
+                                    AutoSizeAxes = Axes.Y
+                                },
+                            },
+                            new Drawable[]
+                            {
+                                new GridContainer
+                                {
+                                    RelativeSizeAxes = Axes.Both,
+                                    ColumnDimensions = new[] { new Dimension(GridSizeMode.AutoSize) },
+                                    Content = new[]
                                     {
-                                        leaderboardFlow = new FillFlowContainer
+                                        new Drawable[]
                                         {
-                                            Anchor = Anchor.CentreLeft,
+                                            leaderboardFlow = new FillFlowContainer
-                                            Origin = Anchor.CentreLeft,
+                                            {
-                                            AutoSizeAxes = Axes.Both,
+                                                Anchor = Anchor.CentreLeft,
-                                            Direction = FillDirection.Vertical,
+                                                Origin = Anchor.CentreLeft,
-                                            Spacing = new Vector2(5)
+                                                AutoSizeAxes = Axes.Both,
-                                        },
+                                                Direction = FillDirection.Vertical,
-                                        grid = new PlayerGrid { RelativeSizeAxes = Axes.Both }
+                                                Spacing = new Vector2(5)
+                                            },
+                                            grid = new PlayerGrid { RelativeSizeAxes = Axes.Both }
+                                        }
                                     }
                                 }
                             }
                         }
                     }
-                })
+                },
+                syncManager = new SpectatorSyncManager(masterClockContainer)
+                {
+                    ReadyToStart = performInitialSeek,
+                }
             };
 
             for (int i = 0; i < Users.Count; i++)
@@ -156,8 +156,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         {
             base.LoadComplete();
 
-            syncManager.ReadyToStart += onReadyToStart;
+            masterClockContainer.Reset();
-            syncManager.MasterState.BindValueChanged(onMasterStateChanged, true);
         }
 
         protected override void Update()
@@ -167,7 +166,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             if (!isCandidateAudioSource(currentAudioSource?.GameplayClock))
             {
                 currentAudioSource = instances.Where(i => isCandidateAudioSource(i.GameplayClock))
-                                              .OrderBy(i => Math.Abs(i.GameplayClock.CurrentTime - syncManager.MasterClock.CurrentTime))
+                                              .OrderBy(i => Math.Abs(i.GameplayClock.CurrentTime - syncManager.CurrentMasterTime))
                                               .FirstOrDefault();
 
                 foreach (var instance in instances)
@@ -175,10 +174,10 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             }
         }
 
-        private bool isCandidateAudioSource(ISpectatorPlayerClock? clock)
+        private bool isCandidateAudioSource(SpectatorPlayerClock? clock)
-            => clock?.IsRunning == true && !clock.IsCatchingUp && !clock.WaitingOnFrames.Value;
+            => clock?.IsRunning == true && !clock.IsCatchingUp && !clock.WaitingOnFrames;
 
-        private void onReadyToStart()
+        private void performInitialSeek()
         {
             // Seek the master clock to the gameplay time.
             // This is chosen as the first available frame in the players' replays, which matches the seek by each individual SpectatorPlayer.
@@ -188,28 +187,8 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
                                         .DefaultIfEmpty(0)
                                         .Min();
 
-            masterClockContainer.Reset(startTime, true);
+            masterClockContainer.StartTime = startTime;
-
+            masterClockContainer.Reset(true);
-            // Although the clock has been started, this flag is set to allow for later synchronisation state changes to also be able to start it.
-            canStartMasterClock = true;
-        }
-
-        private void onMasterStateChanged(ValueChangedEvent<MasterClockState> state)
-        {
-            Logger.Log($"{nameof(MultiSpectatorScreen)}'s master clock become {state.NewValue}");
-
-            switch (state.NewValue)
-            {
-                case MasterClockState.Synchronised:
-                    if (canStartMasterClock)
-                        masterClockContainer.Start();
-
-                    break;
-
-                case MasterClockState.TooFarAhead:
-                    masterClockContainer.Stop();
-                    break;
-            }
         }
 
         protected override void OnNewPlayingUserState(int userId, SpectatorState spectatorState)
@@ -251,7 +230,5 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
 
             return base.OnBackButton();
         }
-
-        protected virtual MasterGameplayClockContainer CreateMasterGameplayClockContainer(WorkingBeatmap beatmap) => new MasterGameplayClockContainer(beatmap, 0);
     }
 }

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

@@ -38,9 +38,9 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         public readonly int UserId;
 
         /// <summary>
-        /// The <see cref="ISpectatorPlayerClock"/> used to control the gameplay running state of a loaded <see cref="Player"/>.
+        /// The <see cref="SpectatorPlayerClock"/> used to control the gameplay running state of a loaded <see cref="Player"/>.
         /// </summary>
-        public readonly ISpectatorPlayerClock GameplayClock;
+        public readonly SpectatorPlayerClock GameplayClock;
 
         /// <summary>
         /// The currently-loaded score.
@@ -55,7 +55,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         private readonly LoadingLayer loadingLayer;
         private OsuScreenStack? stack;
 
-        public PlayerArea(int userId, ISpectatorPlayerClock clock)
+        public PlayerArea(int userId, SpectatorPlayerClock clock)
         {
             UserId = userId;
             GameplayClock = clock;

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

@@ -0,0 +1,100 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Framework.Timing;
+using osu.Game.Screens.Play;
+
+namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
+{
+    /// <summary>
+    /// A clock which catches up using rate adjustment.
+    /// </summary>
+    public class SpectatorPlayerClock : IFrameBasedClock, IAdjustableClock
+    {
+        /// <summary>
+        /// The catch up rate.
+        /// </summary>
+        private const double catchup_rate = 2;
+
+        private readonly GameplayClockContainer masterClock;
+
+        public double CurrentTime { get; private set; }
+
+        /// <summary>
+        /// Whether this clock is waiting on frames to continue playback.
+        /// </summary>
+        public bool WaitingOnFrames { get; set; } = true;
+
+        /// <summary>
+        /// Whether this clock is behind the master clock and running at a higher rate to catch up to it.
+        /// </summary>
+        /// <remarks>
+        /// Of note, this will be false if this clock is *ahead* of the master clock.
+        /// </remarks>
+        public bool IsCatchingUp { get; set; }
+
+        /// <summary>
+        /// Whether this spectator clock should be running.
+        /// Use instead of <see cref="Start"/> / <see cref="Stop"/> to control time.
+        /// </summary>
+        public bool IsRunning { get; set; }
+
+        public SpectatorPlayerClock(GameplayClockContainer masterClock)
+        {
+            this.masterClock = masterClock;
+        }
+
+        public void Reset() => CurrentTime = 0;
+
+        public void Start()
+        {
+            // Our running state should only be managed by SpectatorSyncManager via IsRunning.
+        }
+
+        public void Stop()
+        {
+            // Our running state should only be managed by an SpectatorSyncManager via IsRunning.
+        }
+
+        public bool Seek(double position)
+        {
+            CurrentTime = position;
+            return true;
+        }
+
+        public void ResetSpeedAdjustments()
+        {
+        }
+
+        public double Rate
+        {
+            get => IsCatchingUp ? catchup_rate : 1;
+            set => throw new NotImplementedException();
+        }
+
+        public void ProcessFrame()
+        {
+            if (IsRunning)
+            {
+                double elapsedSource = masterClock.ElapsedFrameTime;
+                double elapsed = elapsedSource * Rate;
+
+                CurrentTime += elapsed;
+                ElapsedFrameTime = elapsed;
+                FramesPerSecond = masterClock.FramesPerSecond;
+            }
+            else
+            {
+                ElapsedFrameTime = 0;
+                FramesPerSecond = 0;
+            }
+        }
+
+        public double ElapsedFrameTime { get; private set; }
+
+        public double FramesPerSecond { get; private set; }
+
+        public FrameTimeInfo TimeInfo => new FrameTimeInfo { Elapsed = ElapsedFrameTime, Current = CurrentTime };
+    }
+}

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

@@ -4,16 +4,16 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using osu.Framework.Bindables;
 using osu.Framework.Graphics;
+using osu.Framework.Logging;
 using osu.Game.Screens.Play;
 
 namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
 {
     /// <summary>
-    /// A <see cref="ISyncManager"/> which synchronises de-synced player clocks through catchup.
+    /// Manages the synchronisation between one or more <see cref="SpectatorPlayerClock"/>s in relation to a master clock.
     /// </summary>
-    public class CatchUpSyncManager : Component, ISyncManager
+    public class SpectatorSyncManager : Component
     {
         /// <summary>
         /// The offset from the master clock to which player clocks should remain within to be considered in-sync.
@@ -30,41 +30,53 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         /// </summary>
         public const double MAXIMUM_START_DELAY = 15000;
 
-        public event Action? ReadyToStart;
+        /// <summary>
+        /// An event which is invoked when gameplay is ready to start.
+        /// </summary>
+        public Action? ReadyToStart;
+
+        public double CurrentMasterTime => masterClock.CurrentTime;
 
         /// <summary>
         /// The master clock which is used to control the timing of all player clocks clocks.
         /// </summary>
-        public GameplayClockContainer MasterClock { get; }
+        private readonly GameplayClockContainer masterClock;
-
-        public IBindable<MasterClockState> MasterState => masterState;
 
         /// <summary>
         /// The player clocks.
         /// </summary>
-        private readonly List<ISpectatorPlayerClock> playerClocks = new List<ISpectatorPlayerClock>();
+        private readonly List<SpectatorPlayerClock> playerClocks = new List<SpectatorPlayerClock>();
 
-        private readonly Bindable<MasterClockState> masterState = new Bindable<MasterClockState>();
+        private MasterClockState masterState = MasterClockState.Synchronised;
 
         private bool hasStarted;
+
         private double? firstStartAttemptTime;
 
-        public CatchUpSyncManager(GameplayClockContainer master)
+        public SpectatorSyncManager(GameplayClockContainer master)
         {
-            MasterClock = master;
+            masterClock = master;
         }
 
-        public ISpectatorPlayerClock CreateManagedClock()
+        /// <summary>
+        /// Create a new managed <see cref="SpectatorPlayerClock"/>.
+        /// </summary>
+        /// <returns>The newly created <see cref="SpectatorPlayerClock"/>.</returns>
+        public SpectatorPlayerClock CreateManagedClock()
         {
-            var clock = new CatchUpSpectatorPlayerClock(MasterClock);
+            var clock = new SpectatorPlayerClock(masterClock);
             playerClocks.Add(clock);
             return clock;
         }
 
-        public void RemoveManagedClock(ISpectatorPlayerClock clock)
+        /// <summary>
+        /// Removes an <see cref="SpectatorPlayerClock"/>, stopping it from being managed by this <see cref="SpectatorSyncManager"/>.
+        /// </summary>
+        /// <param name="clock">The <see cref="SpectatorPlayerClock"/> to remove.</param>
+        public void RemoveManagedClock(SpectatorPlayerClock clock)
         {
             playerClocks.Remove(clock);
-            clock.Stop();
+            clock.IsRunning = false;
         }
 
         protected override void Update()
@@ -75,7 +87,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             {
                 // Ensure all player clocks are stopped until the start succeeds.
                 foreach (var clock in playerClocks)
-                    clock.Stop();
+                    clock.IsRunning = false;
                 return;
             }
 
@@ -95,7 +107,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
             if (playerClocks.Count == 0)
                 return false;
 
-            int readyCount = playerClocks.Count(s => !s.WaitingOnFrames.Value);
+            int readyCount = playerClocks.Count(s => !s.WaitingOnFrames);
 
             if (readyCount == playerClocks.Count)
                 return performStart();
@@ -128,7 +140,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
 
                 // How far this player's clock is out of sync, compared to the master clock.
                 // A negative value means the player is running fast (ahead); a positive value means the player is running behind (catching up).
-                double timeDelta = MasterClock.CurrentTime - clock.CurrentTime;
+                double timeDelta = masterClock.CurrentTime - clock.CurrentTime;
 
                 // Check that the player clock isn't too far ahead.
                 // This is a quiet case in which the catchup is done by the master clock, so IsCatchingUp is not set on the player clock.
@@ -137,15 +149,12 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
                     // Importantly, set the clock to a non-catchup state. if this isn't done, updateMasterState may incorrectly pause the master clock
                     // when it is required to be running (ie. if all players are ahead of the master).
                     clock.IsCatchingUp = false;
-                    clock.Stop();
+                    clock.IsRunning = false;
                     continue;
                 }
 
                 // Make sure the player clock is running if it can.
-                if (!clock.WaitingOnFrames.Value)
+                clock.IsRunning = !clock.WaitingOnFrames;
-                    clock.Start();
-                else
-                    clock.Stop();
 
                 if (clock.IsCatchingUp)
                 {
@@ -167,8 +176,26 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         /// </summary>
         private void updateMasterState()
         {
-            bool anyInSync = playerClocks.Any(s => !s.IsCatchingUp);
+            MasterClockState newState = playerClocks.Any(s => !s.IsCatchingUp) ? MasterClockState.Synchronised : MasterClockState.TooFarAhead;
-            masterState.Value = anyInSync ? MasterClockState.Synchronised : MasterClockState.TooFarAhead;
+
+            if (masterState == newState)
+                return;
+
+            masterState = newState;
+            Logger.Log($"{nameof(SpectatorSyncManager)}'s master clock become {masterState}");
+
+            switch (masterState)
+            {
+                case MasterClockState.Synchronised:
+                    if (hasStarted)
+                        masterClock.Start();
+
+                    break;
+
+                case MasterClockState.TooFarAhead:
+                    masterClock.Stop();
+                    break;
+            }
         }
     }
 }