Do not copy state framebuffers into the core. Aside from modifying data belonging to the core, this ignores the other way that cores can provide video output, OpenGL. Instead, create a video provider for the state and use that.

Author: SuuperW

src/BizHawk.Client.Common/savestates/SavestateFile.cs

@@ -1,6 +1,5 @@
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.IO;
 
 using BizHawk.Bizware.Graphics;
 using BizHawk.Common;
@@ -25,6 +24,7 @@ public class SavestateFile
 		private readonly IEmulator _emulator;
 		private readonly IStatable _statable;
 		private readonly IVideoProvider _videoProvider;
+		public IVideoProvider LoadedVideoProvider = null;
 		private readonly IMovieSession _movieSession;
 
 		private readonly SettingsAdapter _settable;
@@ -215,10 +215,8 @@ loadedSyncSettings is null
 				}
 			}
 
-			if (_videoProvider != null)
-			{
-				bl.GetLump(BinaryStateLump.Framebuffer, false, br => PopulateFramebuffer(br, _videoProvider));
-			}
+
+			bl.GetLump(BinaryStateLump.Framebuffer, false, br => QuickBmpFile.LoadAuto(br.BaseStream, out LoadedVideoProvider));
 
 			string userData = "";
 			bl.GetLump(BinaryStateLump.UserData, abort: false, tr =>
@@ -247,13 +245,5 @@ loadedSyncSettings is null
 
 			return true;
 		}
-
-		private static void PopulateFramebuffer(BinaryReader br, IVideoProvider videoProvider)
-		{
-			using (new SimpleTime("Load Framebuffer"))
-			{
-				QuickBmpFile.Load(videoProvider, br.BaseStream);
-			}
-		}
 	}
 }

src/BizHawk.Client.EmuHawk/IMainFormForTools.cs

@@ -1,3 +1,5 @@
+using System.IO;
+
 using BizHawk.Bizware.Graphics;
 using BizHawk.Client.Common;
 using BizHawk.Emulation.Common;
@@ -64,6 +66,8 @@ public interface IMainFormForTools : IDialogController
 		/// <remarks>only referenced from <see cref="BasicBot"/></remarks>
 		bool LoadQuickSave(int slot, bool suppressOSD = false);
 
+		void LoadState(BinaryReader coreData, IVideoProvider stateScreenshotProvider, string userFriendlyStateName);
+
 		/// <remarks>only referenced from <see cref="MultiDiskBundler"/></remarks>
 		bool LoadRom(string path, LoadRomArgs args);
 

src/BizHawk.Client.EmuHawk/MainForm.cs

@@ -1163,7 +1163,7 @@ public IEmulator Emulator
 			private set
 			{
 				_emulator = value;
-				_currentVideoProvider = value.AsVideoProviderOrDefault();
+				_currentVideoProvider = _coreVideoProvider = value.AsVideoProviderOrDefault();
 				_currentSoundProvider = value.AsSoundProviderOrDefault();
 			}
 		}
@@ -1180,6 +1180,7 @@ private set
 
 		private readonly InputManager InputManager;
 
+		private IVideoProvider _coreVideoProvider = NullVideo.Instance;
 		private IVideoProvider _currentVideoProvider = NullVideo.Instance;
 
 		private ISoundProvider _currentSoundProvider = new NullSound(44100 / 60); // Reasonable default until we have a core instance
@@ -3002,6 +3003,9 @@ private void StepRunLoop_Core(bool force = false)
 			// BlockFrameAdvance (true when input it being editted in TAStudio) supercedes all other frame advance conditions
 			if ((runFrame || force) && !BlockFrameAdvance)
 			{
+				// Reset the video provider. (It may have changed due to loading a save state.)
+				_currentVideoProvider = _coreVideoProvider;
+
 				var isFastForwarding = IsFastForwarding;
 				var isFastForwardingOrRewinding = isFastForwarding || isRewinding || Config.Unthrottled;
 
@@ -4102,24 +4106,64 @@ public void DisableRewind()
 			return File.Exists(path) ? SavestateFile.GetFrameBufferFrom(path) : null;
 		}
 
+		public void LoadState(BinaryReader coreData, IVideoProvider stateScreenshotProvider, string userFriendlyStateName)
+		{
+			IStatable emulator = Emulator.ServiceProvider.GetService<IStatable>();
+			if (emulator == null) return;
+
+			emulator.LoadStateBinary(coreData);
+			if (stateScreenshotProvider != null)
+			{
+				_currentVideoProvider = stateScreenshotProvider;
+			}
+			else
+			{
+				DisplayManager.DiscardApiHawkSurfaces();
+			}
+			// Apparently, we don't reset the counters BEFORE capturing the movie start state. So...
+			if (Emulator.Frame == 0 && MovieSession.Movie.StartsFromSavestate)
+			{
+				Emulator.ResetCounters();
+			}
+
+			LoadStateCommon(userFriendlyStateName);
+		}
+
 		public bool LoadState(string path, string userFriendlyStateName, bool suppressOSD = false) // Move to client.common
 		{
 			if (!Emulator.HasSavestates()) return false;
 			if (ToolControllingSavestates is { } tool) return tool.LoadState();
 
-			if (!new SavestateFile(Emulator, MovieSession, MovieSession.UserBag).Load(path, this))
+			SavestateFile stateFile = new SavestateFile(Emulator, MovieSession, MovieSession.UserBag);
+			if (!stateFile.Load(path, this))
 			{
 				AddOnScreenMessage("Loadstate error!");
 				return false;
 			}
+			else
+			{
+				_currentVideoProvider = stateFile.LoadedVideoProvider;
+			}
 
+			RA?.OnLoadState(path);
+			LoadStateCommon(userFriendlyStateName);
+
+			if (!suppressOSD)
+			{
+				AddOnScreenMessage($"Loaded state: {userFriendlyStateName}");
+			}
+
+			return true;
+		}
+
+		private void LoadStateCommon(string userFriendlyStateName)
+		{
 			OSD.ClearGuiText();
 			if (SavestateLoaded is not null)
 			{
 				StateLoadedEventArgs args = new(userFriendlyStateName);
 				SavestateLoaded(this, args);
 			}
-			RA?.OnLoadState(path);
 
 			if (Tools.Has<LuaConsole>())
 			{
@@ -4138,12 +4182,6 @@ public bool LoadState(string path, string userFriendlyStateName, bool suppressOS
 			{
 				Rewinder?.Clear();
 			}
-
-			if (!suppressOSD)
-			{
-				AddOnScreenMessage($"Loaded state: {userFriendlyStateName}");
-			}
-			return true;
 		}
 
 		public bool LoadQuickSave(int slot, bool suppressOSD = false)

src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.Navigation.cs

@@ -1,4 +1,6 @@
-using BizHawk.Client.Common;
+using System.IO;
+
+using BizHawk.Client.Common;
 
 namespace BizHawk.Client.EmuHawk
 {
@@ -26,7 +28,7 @@ public void GoToFrame(int frame, bool OnLeftMouseDown = false)
 			var closestState = GetPriorStateForFramebuffer(frame);
 			if (frame < Emulator.Frame || closestState.Key > Emulator.Frame)
 			{
-				LoadState(closestState, true);
+				MainForm.LoadState(new BinaryReader(closestState.Value), null, $"frame {closestState.Key}");
 			}
 			closestState.Value.Dispose();
 

src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs

@@ -860,22 +860,6 @@ private KeyValuePair<int,Stream> GetPriorStateForFramebuffer(int frame)
 			return CurrentTasMovie.TasStateManager.GetStateClosestToFrame(frame > 0 ? frame - 1 : 0);
 		}
 
-		public void LoadState(KeyValuePair<int, Stream> state, bool discardApiHawkSurfaces = false)
-		{
-			StatableEmulator.LoadStateBinary(new BinaryReader(state.Value));
-
-			if (state.Key == 0 && CurrentTasMovie.StartsFromSavestate)
-			{
-				Emulator.ResetCounters();
-			}
-
-			UpdateTools();
-			if (discardApiHawkSurfaces)
-			{
-				DisplayManager.DiscardApiHawkSurfaces();
-			}
-		}
-
 		public void AddBranchExternal() => BookMarkControl.AddBranchExternal();
 		public void RemoveBranchExternal() => BookMarkControl.RemoveBranchExternal();
 
@@ -1146,10 +1130,12 @@ public void LoadBranch(TasBranch branch)
 			}
 
 			CurrentTasMovie.LoadBranch(branch);
-			LoadState(new(branch.Frame, new MemoryStream(branch.CoreData, false)));
-
+			MainForm.LoadState(
+				new BinaryReader(new MemoryStream(branch.CoreData)),
+				new BitmapBufferVideoProvider(branch.CoreFrameBuffer),
+				$"branch {branch.UserText}"
+			);
 			CurrentTasMovie.TasStateManager.Capture(Emulator.Frame, Emulator.AsStatable());
-			QuickBmpFile.Copy(new BitmapBufferVideoProvider(branch.CoreFrameBuffer), VideoProvider);
 
 			if (Settings.OldControlSchemeForBranches && TasPlaybackBox.RecordingMode)
 			{