Refactor video player

CollapseLauncher/XAMLs/Theme/CustomControls/LayeredBackgroundImage.Events.Control.cs

@@ -344,11 +344,29 @@ private static bool SaveMediaPosition(object? source, TimeSpan timeSpan)
             timeSpan = timeSpan.Negate();
         }
 
-        ref TimeSpan span = ref CollectionsMarshal.GetValueRefOrAddDefault(SharedLastMediaPosition, hashCode, out _);
-        span = timeSpan;
+        SharedLastMediaPosition[hashCode] = timeSpan;
+
+        TrimSharedLastMediaPositionIfNeeded();
 
         return true;
     }
 
+    private static void TrimSharedLastMediaPositionIfNeeded()
+    {
+        if (SharedLastMediaPosition.Count <= MaxSharedLastMediaPositionEntries)
+            return;
+
+        int excess = SharedLastMediaPosition.Count - MaxSharedLastMediaPositionEntries;
+        foreach (var entry in SharedLastMediaPosition)
+        {
+            if (!SharedLastMediaPosition.TryRemove(entry.Key, out _))
+                continue;
+
+            excess--;
+            if (excess <= 0)
+                break;
+        }
+    }
+
     #endregion
 }

CollapseLauncher/XAMLs/Theme/CustomControls/LayeredBackgroundImage.Events.FrameInitializer.cs

@@ -156,22 +156,32 @@ private unsafe void InitializeRenderTarget()
 
     #region Disposers
 
+    private void DetachVideoPlayerEvents(MediaPlayer player)
+    {
+        player.MediaOpened -= InitializeVideoFrameOnMediaOpened;
+        player.VideoFrameAvailable -= NotifyVideoLoaded;
+        player.VideoFrameAvailable -= VideoPlayer_VideoFrameAvailableUnsafe;
+        player.VideoFrameAvailable -= VideoPlayer_VideoFrameAvailableSafe;
+        player.PlaybackSession.PositionChanged -= MediaDurationPosition_OnChangedBridge;
+    }
+
     private void DisposeVideoPlayer(bool disposeRenderImageSource = true)
     {
         try
         {
-            if (_videoPlayer.IsObjectDisposed())
+            MediaPlayer? player = _videoPlayer;
+            if (player is null || player.IsObjectDisposed())
             {
                 return;
             }
 
-            _videoPlayer.MediaOpened -= InitializeVideoFrameOnMediaOpened;
-            _videoPlayer.Pause();
+            DetachVideoPlayerEvents(player);
+            player.Pause();
 
             // Save last video player duration for later
-            if (_videoPlayer.CanSeek)
+            if (player.CanSeek)
             {
-                _ = SaveMediaPosition(BackgroundSource, _videoPlayer.Position);
+                _ = SaveMediaPosition(BackgroundSource, player.Position);
             }
 
             if (!_useSafeFrameRenderer)
@@ -180,8 +190,7 @@ private void DisposeVideoPlayer(bool disposeRenderImageSource = true)
             }
 
             Interlocked.Exchange(ref _videoFfmpegMediaSource, null)?.Dispose();
-            // ReSharper disable once ConstantConditionalAccessQualifier
-            Interlocked.Exchange(ref _videoPlayer, null!)?.Dispose();
+            Interlocked.Exchange(ref _videoPlayer, null)?.Dispose();
 
             DisposeRenderTarget(disposeRenderImageSource);
         }

CollapseLauncher/XAMLs/Theme/CustomControls/LayeredBackgroundImage.Events.FrameRenderer.cs

@@ -10,7 +10,7 @@
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Media;
 using System;
-using System.Collections.Generic;
+using System.Collections.Concurrent;
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -55,8 +55,9 @@ private static ref readonly Guid IMediaPlayer5_IID
     #endregion
 
     #region Fields
+    private const int MaxSharedLastMediaPositionEntries = 32;
 
-    private static readonly Dictionary<int, TimeSpan> SharedLastMediaPosition = new();
+    private static readonly ConcurrentDictionary<int, TimeSpan> SharedLastMediaPosition = new();
 
     private CanvasRenderTarget? _canvasRenderTarget;
     private nint                _canvasRenderTargetNativePtr;
@@ -462,7 +463,8 @@ public void DisposeAndPauseVideoView(Action?           actionOnPause
             DispatcherQueue?.TryEnqueue(() => SetValue(IsVideoPlayProperty, false));
             actionOnPause?.Invoke();
 
-            if (_videoPlayer == null!)
+            MediaPlayer? playerAtDisposeStart = _videoPlayer;
+            if (playerAtDisposeStart is null)
             {
                 actionAfterPause?.Invoke();
                 return;
@@ -471,26 +473,27 @@ public void DisposeAndPauseVideoView(Action?           actionOnPause
             if (disposeVideoPlayer)
             {
                 // Unsubscribe early to avoid wasted skipped frames.
-                _videoPlayer.VideoFrameAvailable -= !_useSafeFrameRenderer
-                    ? VideoPlayer_VideoFrameAvailableUnsafe
-                    : VideoPlayer_VideoFrameAvailableSafe;
-
-                _videoPlayer.PlaybackSession.PositionChanged -= MediaDurationPosition_OnChangedBridge;
+                DetachVideoPlayerEvents(playerAtDisposeStart);
             }
 
             // Interlocked.Exchange(ref _isBlockVideoFrameDraw, 1); // Blocks early
+            // Guard: skip deferred dispose if the player was already swapped out by a
+            // concurrent source switch (the old player was disposed synchronously).
             PauseVideoView(Impl, volumeFadeDurationMs, volumeFadeResolutionMs, token);
             return;
 
             void Impl()
             {
                 try
                 {
-                    if (_videoPlayer != null! && DispatcherQueue != null!)
+                    if (_videoPlayer != null! &&
+                        ReferenceEquals(_videoPlayer, playerAtDisposeStart) &&
+                        DispatcherQueue != null!)
                     {
                         DispatcherQueue.TryEnqueue(DispatcherQueuePriority.High, () =>
                                                    {
-                                                       if (disposeVideoPlayer)
+                                                       if (disposeVideoPlayer &&
+                                                           ReferenceEquals(_videoPlayer, playerAtDisposeStart))
                                                            DisposeVideoPlayer(disposeRenderImageSource);
                                                    });
                     }

CollapseLauncher/XAMLs/Theme/CustomControls/LayeredBackgroundImage.Events.Loaders.cs

@@ -219,8 +219,16 @@ private void LoadFromSourceAsyncDetached(
 
             if (lastMediaType == MediaSourceType.Video)
             {
-                // Dispose and Invalidate Video Player
-                DisposeAndPauseVideoView();
+                // Synchronously dispose the old player before loading the new source,
+                // cancelling any in-flight fade-out that would otherwise dispose it later.
+                CancellationTokenSource? fadeCts = Interlocked.Exchange(ref _videoPlayerFadeCts, null);
+                fadeCts?.Cancel();
+                fadeCts?.Dispose();
+                SetValue(IsVideoPlayProperty, false);
+                if (_videoPlayer != null!)
+                {
+                    DisposeVideoPlayer();
+                }
             }
 
             _ = InnerLoadDetached().ConfigureAwait(false);
@@ -379,6 +387,11 @@ private static async Task<bool> LoadVideoFromSourceAsync(
                             VideoOutputAllowBgra8 = true,
                             VideoOutputAllowNv12  = true,
                             VideoDecoderMode      = instance.FfmpegDecoderMode
+                        },
+                        General =
+                        {
+                            ReadAheadBufferEnabled  = true,
+                            ReadAheadBufferDuration = TimeSpan.FromSeconds(15)
                         }
                     };
 
@@ -423,6 +436,8 @@ private static async Task<bool> LoadVideoFromSourceAsync(
                             : instance.VideoPlayer_VideoFrameAvailableSafe;
 
                         ffmpegMediaSource.Dispose();
+                        sourceStreamRandom?.Dispose();
+                        sourceStreamRandom = null;
 
                         if (loadFfmpegRetry <= 0)
                         {