Add config option for rewinds every fixed number of frames. (#2893)

* wip consistent rewind intervals.

    In Bizhawk 2.3, rewinds were always made in fixed intervals.
    With the new rewinder, the rewind intervals vary depending on the
    save state size. (This is especially pronounced with delta compression.)
    While this is good for TAStudio, it is awful for regular playing / TASing.

* clean up rewind config gui a bit.

Use radio buttons to make it clear that only the numeric input field of the selected option is being used.

* use more precise variable names.

* minor whitespace cleanup

* don't use fixed rewind intervals by default.

This avoid suddenly changing the rewind behaviour when updating from previous recent versions of Bizhawk.

src/BizHawk.Client.Common/config/RewindConfig.cs

@@ -19,11 +19,21 @@
 		/// </summary>
 		long BufferSize { get; }
 
+		/// <summary>
+		/// Specifies whether TargetFrameLength or TargetRewindInterval is used.
+		/// </summary>
+		public bool UseFixedRewindInterval { get; }
+
 		/// <summary>
 		/// Desired frame length (number of emulated frames you can go back before running out of buffer)
 		/// </summary>
 		int TargetFrameLength { get; }
 
+		/// <summary>
+		/// Desired rewind interval (number of emulated frames you can go back per rewind)
+		/// </summary>
+		int TargetRewindInterval { get; }
+
 		public enum BackingStoreType
 		{
 			Memory,
@@ -39,7 +49,9 @@
 		public bool UseDelta { get; set; }
 		public bool Enabled { get; set; } = true;
 		public long BufferSize { get; set; } = 512; // in mb
+		public bool UseFixedRewindInterval { get; set; } = false;
 		public int TargetFrameLength { get; set; } = 600;
+		public int TargetRewindInterval { get; set; } = 5;
 		public IRewindSettings.BackingStoreType BackingStore { get; set; } = IRewindSettings.BackingStoreType.Memory;
 	}
 }

src/BizHawk.Client.Common/movie/tasproj/ZwinderStateManagerSettings.cs

@@ -107,6 +107,7 @@ namespace BizHawk.Client.Common
 			{
 				UseCompression = CurrentUseCompression,
 				BufferSize = CurrentBufferSize,
+				UseFixedRewindInterval = false,
 				TargetFrameLength = CurrentTargetFrameLength,
 				BackingStore = CurrentStoreType
 			};
@@ -117,6 +118,7 @@ namespace BizHawk.Client.Common
 			{
 				UseCompression = RecentUseCompression,
 				BufferSize = RecentBufferSize,
+				UseFixedRewindInterval = false,
 				TargetFrameLength = RecentTargetFrameLength,
 				BackingStore = RecentStoreType
 			};
@@ -127,6 +129,7 @@ namespace BizHawk.Client.Common
 			{
 				UseCompression = GapsUseCompression,
 				BufferSize = GapsBufferSize,
+				UseFixedRewindInterval = false,
 				TargetFrameLength = GapsTargetFrameLength,
 				BackingStore = GapsStoreType
 			};

src/BizHawk.Client.Common/rewind/ZwinderBuffer.cs

@@ -55,7 +55,16 @@ namespace BizHawk.Client.Common
 				default:
 					throw new ArgumentException("Unsupported store type for ZwinderBuffer.");
 			}
+			if (settings.UseFixedRewindInterval)
+			{
+				_fixedRewindInterval = true;
+				_targetRewindInterval = settings.TargetRewindInterval;
+			}
+			else
+			{
+				_fixedRewindInterval = false;
 				_targetFrameLength = settings.TargetFrameLength;
+			}
 			_states = new StateInfo[STATEMASK + 1];
 			_useCompression = settings.UseCompression;
 		}
@@ -98,7 +107,9 @@ namespace BizHawk.Client.Common
 
 		private readonly long _sizeMask;
 
+		private readonly bool _fixedRewindInterval;
 		private readonly int _targetFrameLength;
+		private readonly int _targetRewindInterval;
 
 		private struct StateInfo
 		{
@@ -130,6 +141,11 @@ namespace BizHawk.Client.Common
 				return 1; // shrug
 			}
 			
+			if (_fixedRewindInterval)
+			{
+				return _targetRewindInterval;
+			}
+
 			// assume that the most recent state size is representative of stuff
 			var sizeRatio = Size / (float)_states[HeadStateIndex].Size;
 			var frameRatio = _targetFrameLength / sizeRatio;
@@ -144,7 +160,8 @@ namespace BizHawk.Client.Common
 			long size = 1L << (int)Math.Floor(Math.Log(targetSize, 2));
 			return Size == size &&
 				_useCompression == settings.UseCompression &&
-				_targetFrameLength == settings.TargetFrameLength &&
+				_fixedRewindInterval == settings.UseFixedRewindInterval &&
+				(_fixedRewindInterval ? _targetRewindInterval == settings.TargetRewindInterval : _targetFrameLength == settings.TargetFrameLength) &&
 				_backingStoreType == settings.BackingStore;
 		}
 
@@ -349,7 +366,9 @@ namespace BizHawk.Client.Common
 				ret = new ZwinderBuffer(new RewindConfig
 				{
 					BufferSize = (int)(size >> 20),
+					UseFixedRewindInterval = false,
 					TargetFrameLength = targetFrameLength,
+					TargetRewindInterval = 5,
 					UseCompression = useCompression
 				});
 				if (ret.Size != size || ret._sizeMask != sizeMask)

src/BizHawk.Client.EmuHawk/config/RewindConfig.Designer.cs

@@ -47,7 +47,7 @@
 			this.labelEx1 = new BizHawk.WinForms.Controls.LabelEx();
 			this.cbDeltaCompression = new System.Windows.Forms.CheckBox();
 			this.TargetFrameLengthNumeric = new System.Windows.Forms.NumericUpDown();
-			this.label2 = new BizHawk.WinForms.Controls.LocLabelEx();
+			this.TargetRewindIntervalNumeric = new System.Windows.Forms.NumericUpDown();
 			this.EstTimeLabel = new BizHawk.WinForms.Controls.LocLabelEx();
 			this.label11 = new BizHawk.WinForms.Controls.LocLabelEx();
 			this.ApproxFramesLabel = new BizHawk.WinForms.Controls.LocLabelEx();
@@ -73,10 +73,13 @@
 			this.label16 = new BizHawk.WinForms.Controls.LocLabelEx();
 			this.BackupSavestatesCheckbox = new System.Windows.Forms.CheckBox();
 			this.label12 = new BizHawk.WinForms.Controls.LocLabelEx();
+			this.TargetFrameLengthRadioButton = new System.Windows.Forms.RadioButton();
+			this.TargetRewindIntervalRadioButton = new System.Windows.Forms.RadioButton();
 			((System.ComponentModel.ISupportInitialize)(this.BufferSizeUpDown)).BeginInit();
 			this.groupBox4.SuspendLayout();
 			this.locSingleRowFLP1.SuspendLayout();
 			((System.ComponentModel.ISupportInitialize)(this.TargetFrameLengthNumeric)).BeginInit();
+			((System.ComponentModel.ISupportInitialize)(this.TargetRewindIntervalNumeric)).BeginInit();
 			this.groupBox6.SuspendLayout();
 			((System.ComponentModel.ISupportInitialize)(this.trackBarCompression)).BeginInit();
 			((System.ComponentModel.ISupportInitialize)(this.nudCompression)).BeginInit();
@@ -120,9 +123,9 @@
 			// UseCompression
 			// 
 			this.UseCompression.AutoSize = true;
-			this.UseCompression.Location = new System.Drawing.Point(15, 170);
+			this.UseCompression.Location = new System.Drawing.Point(15, 194);
 			this.UseCompression.Name = "UseCompression";
-			this.UseCompression.Size = new System.Drawing.Size(306, 17);
+			this.UseCompression.Size = new System.Drawing.Size(324, 17);
 			this.UseCompression.TabIndex = 5;
 			this.UseCompression.Text = "Use zlib compression (economizes buffer usage at cost of CPU)";
 			this.UseCompression.UseVisualStyleBackColor = true;
@@ -136,7 +139,7 @@
 			// 
 			// BufferSizeUpDown
 			// 
-			this.BufferSizeUpDown.Location = new System.Drawing.Point(0, 0);
+			this.BufferSizeUpDown.Location = new System.Drawing.Point(25, 3);
 			this.BufferSizeUpDown.Maximum = new decimal(new int[] {
 			15,
 			0,
@@ -189,10 +192,12 @@
 			// 
 			// groupBox4
 			// 
+			this.groupBox4.Controls.Add(this.TargetRewindIntervalRadioButton);
+			this.groupBox4.Controls.Add(this.TargetFrameLengthRadioButton);
 			this.groupBox4.Controls.Add(this.locSingleRowFLP1);
 			this.groupBox4.Controls.Add(this.cbDeltaCompression);
 			this.groupBox4.Controls.Add(this.TargetFrameLengthNumeric);
-			this.groupBox4.Controls.Add(this.label2);
+			this.groupBox4.Controls.Add(this.TargetRewindIntervalNumeric);
 			this.groupBox4.Controls.Add(this.UseCompression);
 			this.groupBox4.Controls.Add(this.RewindEnabledBox);
 			this.groupBox4.Controls.Add(this.label3);
@@ -208,7 +213,7 @@
 			this.groupBox4.Controls.Add(this.StateSizeLabel);
 			this.groupBox4.Location = new System.Drawing.Point(12, 12);
 			this.groupBox4.Name = "groupBox4";
-			this.groupBox4.Size = new System.Drawing.Size(371, 218);
+			this.groupBox4.Size = new System.Drawing.Size(371, 248);
 			this.groupBox4.TabIndex = 2;
 			this.groupBox4.TabStop = false;
 			this.groupBox4.Text = "RewindSettings";
@@ -244,16 +249,16 @@
 			// cbDeltaCompression
 			// 
 			this.cbDeltaCompression.AutoSize = true;
-			this.cbDeltaCompression.Location = new System.Drawing.Point(15, 193);
+			this.cbDeltaCompression.Location = new System.Drawing.Point(15, 217);
 			this.cbDeltaCompression.Name = "cbDeltaCompression";
-			this.cbDeltaCompression.Size = new System.Drawing.Size(149, 17);
+			this.cbDeltaCompression.Size = new System.Drawing.Size(332, 17);
 			this.cbDeltaCompression.TabIndex = 35;
 			this.cbDeltaCompression.Text = "Use delta compression (economizes buffer usage at cost of CPU)";
 			this.cbDeltaCompression.UseVisualStyleBackColor = true;
 			// 
 			// TargetFrameLengthNumeric
 			// 
-			this.TargetFrameLengthNumeric.Location = new System.Drawing.Point(125, 135);
+			this.TargetFrameLengthNumeric.Location = new System.Drawing.Point(146, 138);
 			this.TargetFrameLengthNumeric.Maximum = new decimal(new int[] {
 			500000,
 			0,
@@ -273,11 +278,27 @@
 			0,
 			0});
 			// 
-			// label2
+			// TargetRewindIntervalNumeric
 			// 
-			this.label2.Location = new System.Drawing.Point(12, 138);
+			this.TargetRewindIntervalNumeric.Location = new System.Drawing.Point(231, 162);
-			this.label2.Name = "label2";
+			this.TargetRewindIntervalNumeric.Maximum = new decimal(new int[] {
-			this.label2.Text = "Desired frame length:";
+			500000,
+			0,
+			0,
+			0});
+			this.TargetRewindIntervalNumeric.Minimum = new decimal(new int[] {
+			1,
+			0,
+			0,
+			0});
+			this.TargetRewindIntervalNumeric.Name = "TargetRewindIntervalNumeric";
+			this.TargetRewindIntervalNumeric.Size = new System.Drawing.Size(52, 20);
+			this.TargetRewindIntervalNumeric.TabIndex = 21;
+			this.TargetRewindIntervalNumeric.Value = new decimal(new int[] {
+			5,
+			0,
+			0,
+			0});
 			// 
 			// EstTimeLabel
 			// 
@@ -365,7 +386,7 @@
 			this.trackBarCompression.Location = new System.Drawing.Point(22, 37);
 			this.trackBarCompression.Maximum = 9;
 			this.trackBarCompression.Name = "trackBarCompression";
-			this.trackBarCompression.Size = new System.Drawing.Size(157, 42);
+			this.trackBarCompression.Size = new System.Drawing.Size(157, 45);
 			this.trackBarCompression.TabIndex = 1;
 			this.toolTip1.SetToolTip(this.trackBarCompression, "0 = None; 9 = Maximum");
 			this.trackBarCompression.Value = 1;
@@ -508,6 +529,28 @@
 			this.label12.Name = "label12";
 			this.label12.Text = "Compression Level";
 			// 
+			// TargetFrameLengthRadioButton
+			// 
+			this.TargetFrameLengthRadioButton.AutoSize = true;
+			this.TargetFrameLengthRadioButton.Location = new System.Drawing.Point(15, 138);
+			this.TargetFrameLengthRadioButton.Name = "TargetFrameLengthRadioButton";
+			this.TargetFrameLengthRadioButton.Size = new System.Drawing.Size(125, 17);
+			this.TargetFrameLengthRadioButton.TabIndex = 48;
+			this.TargetFrameLengthRadioButton.TabStop = true;
+			this.TargetFrameLengthRadioButton.Text = "Desired frame length:";
+			this.TargetFrameLengthRadioButton.UseVisualStyleBackColor = true;
+			// 
+			// TargetRewindIntervalRadioButton
+			// 
+			this.TargetRewindIntervalRadioButton.AutoSize = true;
+			this.TargetRewindIntervalRadioButton.Location = new System.Drawing.Point(15, 162);
+			this.TargetRewindIntervalRadioButton.Name = "TargetRewindIntervalRadioButton";
+			this.TargetRewindIntervalRadioButton.Size = new System.Drawing.Size(210, 17);
+			this.TargetRewindIntervalRadioButton.TabIndex = 49;
+			this.TargetRewindIntervalRadioButton.TabStop = true;
+			this.TargetRewindIntervalRadioButton.Text = "Rewinds every fixed number of frames: ";
+			this.TargetRewindIntervalRadioButton.UseVisualStyleBackColor = true;
+			// 
 			// RewindConfig
 			// 
 			this.AcceptButton = this.OK;
@@ -532,6 +575,7 @@
 			this.locSingleRowFLP1.ResumeLayout(false);
 			this.locSingleRowFLP1.PerformLayout();
 			((System.ComponentModel.ISupportInitialize)(this.TargetFrameLengthNumeric)).EndInit();
+			((System.ComponentModel.ISupportInitialize)(this.TargetRewindIntervalNumeric)).EndInit();
 			this.groupBox6.ResumeLayout(false);
 			this.groupBox6.PerformLayout();
 			((System.ComponentModel.ISupportInitialize)(this.trackBarCompression)).EndInit();
@@ -583,11 +627,13 @@
 				private System.Windows.Forms.CheckBox BackupSavestatesCheckbox;
 				private BizHawk.WinForms.Controls.LocLabelEx label20;
 		private System.Windows.Forms.NumericUpDown TargetFrameLengthNumeric;
-		private BizHawk.WinForms.Controls.LocLabelEx label2;
+		private System.Windows.Forms.NumericUpDown TargetRewindIntervalNumeric;
 		private System.Windows.Forms.CheckBox cbDeltaCompression;
 		private WinForms.Controls.LocSingleRowFLP locSingleRowFLP1;
 		private WinForms.Controls.LabelEx labelEx3;
 		private WinForms.Controls.LabelEx labelEx2;
 		private WinForms.Controls.LabelEx labelEx1;
+		private System.Windows.Forms.RadioButton TargetFrameLengthRadioButton;
+		private System.Windows.Forms.RadioButton TargetRewindIntervalRadioButton;
 	}
 }

src/BizHawk.Client.EmuHawk/config/RewindConfig.cs

@@ -49,7 +49,10 @@ namespace BizHawk.Client.EmuHawk
 			UseCompression.Checked = _config.Rewind.UseCompression;
 			cbDeltaCompression.Checked = _config.Rewind.UseDelta;
 			BufferSizeUpDown.Value = Math.Max((decimal) Math.Log(_config.Rewind.BufferSize, 2), BufferSizeUpDown.Minimum);
+			TargetFrameLengthRadioButton.Checked = !_config.Rewind.UseFixedRewindInterval;
+			TargetRewindIntervalRadioButton.Checked = _config.Rewind.UseFixedRewindInterval;
 			TargetFrameLengthNumeric.Value = Math.Max(_config.Rewind.TargetFrameLength, TargetFrameLengthNumeric.Minimum);
+			TargetRewindIntervalNumeric.Value = Math.Max(_config.Rewind.TargetRewindInterval, TargetRewindIntervalNumeric.Minimum);
 			StateSizeLabel.Text = FormatKB(_avgStateSize);
 			CalculateEstimates();
 
@@ -111,7 +114,9 @@ namespace BizHawk.Client.EmuHawk
 			_config.Rewind.UseCompression = PutRewindSetting(_config.Rewind.UseCompression, UseCompression.Checked);
 			_config.Rewind.Enabled = PutRewindSetting(_config.Rewind.Enabled, RewindEnabledBox.Checked);
 			_config.Rewind.BufferSize = PutRewindSetting(_config.Rewind.BufferSize, 1L << (int) BufferSizeUpDown.Value);
+			_config.Rewind.UseFixedRewindInterval = PutRewindSetting(_config.Rewind.UseFixedRewindInterval, TargetRewindIntervalRadioButton.Checked);
 			_config.Rewind.TargetFrameLength = PutRewindSetting(_config.Rewind.TargetFrameLength, (int)TargetFrameLengthNumeric.Value);
+			_config.Rewind.TargetRewindInterval = PutRewindSetting(_config.Rewind.TargetRewindInterval, (int)TargetRewindIntervalNumeric.Value);
 			_config.Rewind.UseDelta = PutRewindSetting(_config.Rewind.UseDelta, cbDeltaCompression.Checked);
 
 			// These settings are not used by DoRewindSettings