adjust VideoPlayer to unload AV1 streams on Unload

src/Video/VideoAV1Stream.cs

@@ -8,6 +8,7 @@ namespace MoonWorks.Video
 		public IntPtr Handle => handle;
 		IntPtr handle;
 
+		public bool Loaded => handle != IntPtr.Zero;
 		public bool Ended => Dav1dfile.df_eos(Handle) == 1;
 
 		public IntPtr yDataHandle;
@@ -20,21 +21,41 @@ namespace MoonWorks.Video
 
 		public bool FrameDataUpdated { get; set; }
 
+		private VideoAV1 Parent;
+
 		public VideoAV1Stream(GraphicsDevice device, VideoAV1 video) : base(device)
 		{
-			if (Dav1dfile.df_fopen(video.Filename, out handle) == 0)
+			handle = IntPtr.Zero;
-			{
+			Parent = video;
-				throw new Exception("Failed to open video file!");
+		}
-			}
 
-			Reset();
+		public void Load()
+		{
+			if (!Loaded)
+			{
+				if (Dav1dfile.df_fopen(Parent.Filename, out handle) == 0)
+				{
+					throw new Exception("Failed to load video file!");
+				}
+
+				Reset();
+			}
+		}
+
+		public void Unload()
+		{
+			if (Loaded)
+			{
+				Dav1dfile.df_close(handle);
+				handle = IntPtr.Zero;
+			}
 		}
 
 		public void Reset()
 		{
 			lock (this)
 			{
-				Dav1dfile.df_reset(Handle);
+				Dav1dfile.df_reset(handle);
 				ReadNextFrame();
 			}
 		}
@@ -46,7 +67,7 @@ namespace MoonWorks.Video
 				if (!Ended)
 				{
 					if (Dav1dfile.df_readvideo(
-						Handle,
+						handle,
 						1,
 						out var yDataHandle,
 						out var uDataHandle,
@@ -74,7 +95,7 @@ namespace MoonWorks.Video
 		{
 			if (!IsDisposed)
 			{
-				Dav1dfile.df_close(Handle);
+				Unload();
 			}
 			base.Dispose(disposing);
 		}

src/Video/VideoPlayer.cs

@@ -164,9 +164,18 @@ namespace MoonWorks.Video
 		/// </summary>
 		public void Unload()
 		{
-			Stop();
+			ReadNextFrameTask?.Wait();
 			ResetTask?.Wait();
 			ResetSecondaryStreamTask?.Wait();
+
+			Stop();
+
+			Video.StreamA.Unload();
+			Video.StreamB.Unload();
+
+			ReadNextFrameTask = null;
+			ResetTask = null;
+			ResetSecondaryStreamTask = null;
 			Video = null;
 		}
 
@@ -224,6 +233,7 @@ namespace MoonWorks.Video
 			lock (CurrentStream)
 			{
 				ResetTask?.Wait();
+				ResetTask = null;
 
 				var commandBuffer = Device.AcquireCommandBuffer();
 
@@ -322,7 +332,11 @@ namespace MoonWorks.Video
 
 		private void InitializeDav1dStream()
 		{
+			Video.StreamA.Load();
+			Video.StreamB.Load();
+
 			ReadNextFrameTask?.Wait();
+			ReadNextFrameTask = null;
 
 			ResetTask = Task.Run(Video.StreamA.Reset);
 			ResetTask.ContinueWith(HandleTaskException, TaskContinuationOptions.OnlyOnFaulted);