fully support read-only movie opening. I hope this fixes #453

BizHawk.Client.Common/movie/MovieService.cs

@@ -19,7 +19,7 @@ namespace BizHawk.Client.Common
 			if (Path.GetExtension(path).EndsWith("bkm"))
 			{
 				var bkm = new BkmMovie(path);
-				bkm.Load();
+				bkm.Load(false);
 
 				// Hackery to fix how things used to work
 				if (bkm.SystemID == "GBC")

BizHawk.Client.Common/movie/MovieSession.cs

@@ -182,7 +182,7 @@ namespace BizHawk.Client.Common
 		public bool MovieLoad()
 		{
 			MovieControllerAdapter = Movie.LogGeneratorInstance().MovieControllerAdapter;
-			return Movie.Load();
+			return Movie.Load(false);
 		}
 
 		public void StopMovie(bool saveChanges = true)
@@ -463,7 +463,7 @@ namespace BizHawk.Client.Common
 		{
 			if (!record) // The semantics of record is that we are starting a new movie, and even wiping a pre-existing movie with the same path, but non-record means we are loading an existing movie into playback mode
 			{
-				movie.Load();
+				movie.Load(false);
 				if (movie.SystemID != emulator.SystemId)
 				{
 					throw new MoviePlatformMismatchException(

BizHawk.Client.Common/movie/bk2/Bk2Movie.IO.cs

@@ -32,7 +32,7 @@ namespace BizHawk.Client.Common
 			Write(backupName);
 		}
 
-		public virtual bool Load()
+		public virtual bool Load(bool preload)
 		{
 			var file = new FileInfo(Filename);
 			if (!file.Exists)
@@ -158,7 +158,6 @@ namespace BizHawk.Client.Common
 
 		public bool PreLoadHeaderAndLength(HawkFile hawkFile)
 		{
-			// For now, preload simply loads everything
 			var file = new FileInfo(Filename);
 			if (!file.Exists)
 			{
@@ -166,7 +165,7 @@ namespace BizHawk.Client.Common
 			}
 
 			Filename = file.FullName;
-			return Load();
+			return Load(true);
 		}
 
 		protected virtual void Write(string fn)

BizHawk.Client.Common/movie/bkm/BkmMovie.IO.cs

@@ -58,7 +58,7 @@ namespace BizHawk.Client.Common
 			Write(backupName);
 		}
 
-		public bool Load()
+		public bool Load(bool preload)
 		{
 			var file = new FileInfo(Filename);
 

BizHawk.Client.Common/movie/conversions/MovieConversionExtensions.cs

@@ -34,6 +34,7 @@ namespace BizHawk.Client.Common.MovieConversionExtensions
 			}
 
 			var tas = new TasMovie(newFilename, old.StartsFromSavestate);
+			tas.TasStateManager.MountWriteAccess();
 
 			for (var i = 0; i < old.InputLogLength; i++)
 			{

BizHawk.Client.Common/movie/import/MovieImport.cs

@@ -140,7 +140,7 @@ namespace BizHawk.Client.Common
 						break;
 					case ".BKM":
 						m.Filename = path;
-						m.Load();
+						m.Load(false);
 						break;
 				}
 			}

BizHawk.Client.Common/movie/interfaces/IMovie.cs

@@ -99,7 +99,7 @@ namespace BizHawk.Client.Common
 		/// Tells the movie to load the contents of Filename
 		/// </summary>
 		/// <returns>Return whether or not the file was successfully loaded</returns>
-		bool Load();
+		bool Load(bool preload);
 
 		/// <summary>
 		/// Instructs the movie to save the current contents to Filename

BizHawk.Client.Common/movie/tasproj/TasMovie.IO.cs

@@ -107,7 +107,7 @@ namespace BizHawk.Client.Common
 			Changes = false;
 		}
 
-		public override bool Load()
+		public override bool Load(bool preload)
 		{
 			var file = new FileInfo(Filename);
 			if (!file.Exists)
@@ -221,16 +221,20 @@ namespace BizHawk.Client.Common
 					StateManager.Settings.PopulateFromString(tr.ReadToEnd());
 				});
 
-				if (StateManager.Settings.SaveStateHistory)
+				if(!preload)
 				{
-					bl.GetLump(BinaryStateLump.StateHistory, false, delegate(BinaryReader br, long length)
+					if (StateManager.Settings.SaveStateHistory)
 					{
-						StateManager.Load(br);
-					});
+						bl.GetLump(BinaryStateLump.StateHistory, false, delegate(BinaryReader br, long length)
+						{
+							StateManager.Load(br);
+						});
+					}
+
+					// Movie should always have a state at frame 0.
+					if (!this.StartsFromSavestate)
+						StateManager.Capture();
 				}
-				// Movie should always have a state at frame 0.
-				if (!this.StartsFromSavestate)
-					StateManager.Capture();
 
 				bl.GetLump(BinaryStateLump.Markers, false, delegate(TextReader tr)
 				{

BizHawk.Client.Common/movie/tasproj/TasStateManager.cs

@@ -36,7 +36,7 @@ namespace BizHawk.Client.Common
 		}
 
 		private Guid guid = Guid.NewGuid();
-		private readonly SortedList<int, byte[]> States = new SortedList<int, byte[]>();
+		private SortedList<int, byte[]> States = new SortedList<int, byte[]>();
 		private string statePath
 		{
 			get
@@ -46,6 +46,7 @@ namespace BizHawk.Client.Common
 			}
 		}
 
+		private bool _isMountedForWrite;
 		private readonly TasMovie _movie;
 		private ulong _expectedStateSize = 0;
 
@@ -80,6 +81,25 @@ namespace BizHawk.Client.Common
 
 			Settings = new TasStateManagerSettings(Global.Config.DefaultTasProjSettings);
 
+			accessed = new List<int>();
+		}
+
+		/// <summary>
+		/// Mounts this instance for write access. Prior to that it's read-only
+		/// </summary>
+		public void MountWriteAccess()
+		{
+			if (_isMountedForWrite)
+				return;
+
+			_isMountedForWrite = true;
+
+			if (Directory.Exists(statePath))
+			{
+				Directory.Delete(statePath, true); // To delete old files that may still exist.
+			}
+			Directory.CreateDirectory(statePath);
+
 			int limit = 0;
 
 			_expectedStateSize = (ulong)Core.SaveStateBinary().Length;
@@ -90,20 +110,6 @@ namespace BizHawk.Client.Common
 			}
 
 			States = new SortedList<int, byte[]>(limit);
-
-			accessed = new List<int>();
-		}
-
-		/// <summary>
-		/// Mounts this instance for write access. Prior to that it's read-only
-		/// </summary>
-		public void MountWriteAccess()
-		{
-			if (Directory.Exists(statePath))
-			{
-				Directory.Delete(statePath, true); // To delete old files that may still exist.
-			}
-			Directory.CreateDirectory(statePath);
 		}
 
 		public TasStateManagerSettings Settings { get; set; }

BizHawk.Client.EmuHawk/MainForm.Movie.cs

@@ -30,6 +30,9 @@ namespace BizHawk.Client.EmuHawk
 
 			try
 			{
+				var tasmovie = (movie as TasMovie);
+				if (tasmovie != null)
+					tasmovie.TasStateManager.MountWriteAccess();
 				Global.MovieSession.QueueNewMovie(movie, record, Global.Emulator);
 			}
 			catch (MoviePlatformMismatchException ex)

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

@@ -407,7 +407,7 @@ namespace BizHawk.Client.EmuHawk
 			CurrentTasMovie.Filename = file.FullName;
 			try
 			{
-				CurrentTasMovie.Load();
+				CurrentTasMovie.Load(false);
 			}
 			catch
 			{