Fixup multisession handling with MDS and improve its track/sector size handling, also maybe fix it entirely? (not sure if this ever worked)

Move the various synths using the CUE SS_Base to a file, mostly just a nicer organizational change as MDS and CDI use one of these but not CUE
Misc improvements elsewhere

src/BizHawk.Emulation.DiscSystem/DiscFormats/CDI_format.cs

@@ -443,52 +443,6 @@ namespace BizHawk.Emulation.DiscSystem
 			return ret;
 		}
 
-		private class SS_CDI_RawQ : SS_Base
-		{
-			public override void Synth(SectorSynthJob job)
-			{
-				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset, 2352);
-
-				if ((job.Parts & ESectorSynthPart.SubchannelP) != 0)
-				{
-					SynthUtils.SubP(job.DestBuffer2448, job.DestOffset + 2352, Pause);
-				}
-
-				// Q is present in the blob and non-interleaved
-				if ((job.Parts & ESectorSynthPart.SubchannelQ) != 0)
-				{
-					Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 2352 + 12, 12);
-				}
-
-				//clear R-W if needed
-				if ((job.Parts & ESectorSynthPart.Subchannel_RSTUVW) != 0)
-				{
-					Array.Clear(job.DestBuffer2448, job.DestOffset + 2352 + 12 + 12, 12 * 6);
-				}
-
-				//subcode has been generated deinterleaved; we may still need to interleave it
-				if ((job.Parts & ESectorSynthPart.SubcodeAny) != 0 && (job.Parts & ESectorSynthPart.SubcodeDeinterleave) == 0)
-				{
-					SynthUtils.InterleaveSubcodeInplace(job.DestBuffer2448, job.DestOffset + 2352);
-				}
-			}
-		}
-
-		private class SS_CDI_RawPQRSTUVW : SS_Base
-		{
-			public override void Synth(SectorSynthJob job)
-			{
-				// all subcode is present and interleaved, just read it all
-				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset, 2448);
-
-				// deinterleave it if needed
-				if ((job.Parts & ESectorSynthPart.SubcodeDeinterleave) != 0)
-				{
-					SynthUtils.DeinterleaveSubcodeInplace(job.DestBuffer2448, job.DestOffset + 2352);
-				}
-			}
-		}
-
 		/// <exception cref="CDIParseException">file <paramref name="cdiPath"/> not found</exception>
 		public static Disc LoadCDIToDisc(string cdiPath, DiscMountPolicy IN_DiscMountPolicy)
 		{
@@ -559,8 +513,8 @@ namespace BizHawk.Emulation.DiscSystem
 							0 => new SS_Mode1_2048(),
 							1 => new SS_Mode2_2336(),
 							2 => new SS_2352(),
-							3 => new SS_CDI_RawQ(),
+							3 => new SS_2364_DeinterleavedQ(),
-							4 => new SS_CDI_RawPQRSTUVW(),
+							4 => new SS_2448_Interleaved(),
 							_ => throw new InvalidOperationException()
 						};
 						synth.Blob = cdiBlob;

src/BizHawk.Emulation.DiscSystem/DiscFormats/CUE/CUE_SynthExtras.cs

@@ -0,0 +1,127 @@
+using System;
+
+namespace BizHawk.Emulation.DiscSystem.CUE
+{
+	// extra synths using SS_Base, not used by CUEs but used for other formats
+
+	/// <summary>
+	/// Represents a Mode2 Form1 2048-byte sector
+	/// Only used by MDS
+	/// </summary>
+	internal class SS_Mode2_Form1_2048 : SS_Base
+	{
+		public override void Synth(SectorSynthJob job)
+		{
+			var ecm = (job.Parts & ESectorSynthPart.ECMAny) != 0;
+			if (ecm)
+			{
+				// ecm needs these parts for synth
+				job.Parts |= ESectorSynthPart.User2048;
+				job.Parts |= ESectorSynthPart.Header16;
+			}
+
+			//read the sector user data
+			if ((job.Parts & ESectorSynthPart.User2048) != 0)
+				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 24, 2048);
+
+			if ((job.Parts & ESectorSynthPart.Header16) != 0)
+				SynthUtils.SectorHeader(job.DestBuffer2448, job.DestOffset + 0, job.LBA, 2);
+
+			if (ecm)
+				SynthUtils.ECM_Mode2_Form1(job.DestBuffer2448, job.DestOffset);
+
+			SynthSubchannelAsNeed(job);
+		}
+	}
+
+	/// <summary>
+	/// Represents a Mode2 Form1 2324-byte sector
+	/// Only used by MDS
+	/// </summary>
+	internal class SS_Mode2_Form2_2324 : SS_Base
+	{
+		public override void Synth(SectorSynthJob job)
+		{
+			//read the sector userdata (note: ECC data is now userdata in this regard)
+			if ((job.Parts & ESectorSynthPart.User2336) != 0)
+			{
+				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 24, 2324);
+				// only needs userdata for synth
+				SynthUtils.ECM_Mode2_Form2(job.DestBuffer2448, job.DestOffset);
+			}
+
+			if ((job.Parts & ESectorSynthPart.Header16) != 0)
+				SynthUtils.SectorHeader(job.DestBuffer2448, job.DestOffset + 0, job.LBA, 2);
+
+			SynthSubchannelAsNeed(job);
+		}
+	}
+
+	/// <summary>
+	/// Represents a Mode2 Form1 2328-byte sector
+	/// Only used by MDS
+	/// </summary>
+	internal class SS_Mode2_Form2_2328 : SS_Base
+	{
+		public override void Synth(SectorSynthJob job)
+		{
+			//read the sector userdata (note: ECC data is now userdata in this regard)
+			if ((job.Parts & ESectorSynthPart.User2336) != 0)
+			{
+				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 24, 2328);
+				// only subheader needs to be synthed
+				SynthUtils.SectorSubHeader(job.DestBuffer2448, job.DestOffset + 16, 2);
+			}
+
+			if ((job.Parts & ESectorSynthPart.Header16) != 0)
+				SynthUtils.SectorHeader(job.DestBuffer2448, job.DestOffset + 0, job.LBA, 2);
+
+			SynthSubchannelAsNeed(job);
+		}
+	}
+
+	/// <summary>
+	/// Represents a full 2448-byte sector with interleaved subcode
+	/// Only used by MDS and CDI
+	/// </summary>
+	internal class SS_2448_Interleaved : SS_Base
+	{
+		public override void Synth(SectorSynthJob job)
+		{
+			// all subcode is present and interleaved, just read it all
+			Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset, 2448);
+
+			// deinterleave it if needed
+			if ((job.Parts & ESectorSynthPart.SubcodeDeinterleave) != 0)
+				SynthUtils.DeinterleaveSubcodeInplace(job.DestBuffer2448, job.DestOffset + 2352);
+		}
+	}
+
+	/// <summary>
+	/// Represents a 2364-byte (2352 + 12) sector with deinterleaved Q subcode
+	/// Only used by CDI
+	/// </summary>
+	internal class SS_2364_DeinterleavedQ : SS_Base
+	{
+		public override void Synth(SectorSynthJob job)
+		{
+			if ((job.Parts & ESectorSynthPart.User2352) != 0)
+				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset, 2352);
+
+			if ((job.Parts & ESectorSynthPart.SubchannelP) != 0)
+				SynthUtils.SubP(job.DestBuffer2448, job.DestOffset + 2352, Pause);
+
+			// Q is present in the blob and non-interleaved
+			if ((job.Parts & ESectorSynthPart.SubchannelQ) != 0)
+				Blob.Read(BlobOffset + 2352, job.DestBuffer2448, job.DestOffset + 2352 + 12, 12);
+
+			// clear R-W if needed
+			if ((job.Parts & ESectorSynthPart.Subchannel_RSTUVW) != 0)
+				Array.Clear(job.DestBuffer2448, job.DestOffset + 2352 + 12 + 12, 12 * 6);
+
+			// subcode has been generated deinterleaved; we may still need to interleave it
+			if ((job.Parts & ESectorSynthPart.SubcodeAny) != 0 && (job.Parts & ESectorSynthPart.SubcodeDeinterleave) == 0)
+				SynthUtils.InterleaveSubcodeInplace(job.DestBuffer2448, job.DestOffset + 2352);
+		}
+	}
+}

src/BizHawk.Emulation.DiscSystem/DiscFormats/CUE/CUE_Synths.cs

@@ -39,11 +39,10 @@ namespace BizHawk.Emulation.DiscSystem.CUE
 			}
 
 			//subcode has been generated deinterleaved; we may still need to interleave it
-			if((job.Parts & ESectorSynthPart.SubcodeAny) != 0)
+			if ((job.Parts & ESectorSynthPart.SubcodeAny) != 0 && (job.Parts & ESectorSynthPart.SubcodeDeinterleave) == 0)
-				if ((job.Parts & (ESectorSynthPart.SubcodeDeinterleave)) == 0)
+			{
-				{
+				SynthUtils.InterleaveSubcodeInplace(job.DestBuffer2448, job.DestOffset + 2352);
-					SynthUtils.InterleaveSubcodeInplace(job.DestBuffer2448, job.DestOffset + 2352);
+			}
-				}
 		}
 	}
 
@@ -54,15 +53,23 @@ namespace BizHawk.Emulation.DiscSystem.CUE
 	{
 		public override void Synth(SectorSynthJob job)
 		{
+			var ecm = (job.Parts & ESectorSynthPart.ECMAny) != 0;
+			if (ecm)
+			{
+				// ecm needs these parts for synth
+				job.Parts |= ESectorSynthPart.User2048;
+				job.Parts |= ESectorSynthPart.Header16;
+			}
+
 			//read the sector user data
-			if((job.Parts & ESectorSynthPart.User2048) != 0)
+			if ((job.Parts & ESectorSynthPart.User2048) != 0)
 				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 16, 2048);
 
 			if ((job.Parts & ESectorSynthPart.Header16) != 0)
 				SynthUtils.SectorHeader(job.DestBuffer2448, job.DestOffset + 0, job.LBA, 1);
 
-			if ((job.Parts & ESectorSynthPart.ECMAny) != 0)
+			if (ecm)
-				SynthUtils.ECM_Mode1(job.DestBuffer2448, job.DestOffset + 0, job.LBA);
+				SynthUtils.ECM_Mode1(job.DestBuffer2448, job.DestOffset + 0);
 
 			SynthSubchannelAsNeed(job);
 		}
@@ -75,8 +82,9 @@ namespace BizHawk.Emulation.DiscSystem.CUE
 	{
 		public override void Synth(SectorSynthJob job)
 		{
-			//read the sector user data
+			//read the sector sector user data + ECM data
-			Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 16, 2336);
+			if ((job.Parts & ESectorSynthPart.User2336) != 0)
+				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 16, 2336);
 
 			if ((job.Parts & ESectorSynthPart.Header16) != 0)
 				SynthUtils.SectorHeader(job.DestBuffer2448, job.DestOffset + 0, job.LBA, 2);
@@ -94,7 +102,8 @@ namespace BizHawk.Emulation.DiscSystem.CUE
 		public override void Synth(SectorSynthJob job)
 		{
 			//read the sector user data
-			Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset, 2352);
+			if ((job.Parts & ESectorSynthPart.User2352) != 0)
+				Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset, 2352);
 
 			//if subcode is needed, synthesize it
 			SynthSubchannelAsNeed(job);
@@ -159,7 +168,7 @@ namespace BizHawk.Emulation.DiscSystem.CUE
 				case 1:
 				{
 					if ((job.Parts & ESectorSynthPart.ECMAny) != 0)
-						SynthUtils.ECM_Mode1(job.DestBuffer2448, job.DestOffset + 0, job.LBA);
+						SynthUtils.ECM_Mode1(job.DestBuffer2448, job.DestOffset + 0);
 					break;
 				}
 				case 2 when form == 2:
@@ -170,6 +179,4 @@ namespace BizHawk.Emulation.DiscSystem.CUE
 			SynthSubchannelAsNeed(job);
 		}
 	}
-
-
 }

src/BizHawk.Emulation.DiscSystem/DiscFormats/MDS_Format.cs

@@ -154,9 +154,9 @@ namespace BizHawk.Emulation.DiscSystem
 		public class ATrack
 		{
 			/// <summary>
-			/// The specified data mode
+			/// The specified data mode (only lower 3 bits are actually meaningful)
 			/// 0x00    -   None (no data)
-			/// 0x02    -   DVD
+			/// 0x02    -   DVD (when header specifies DVD, Mode1 otherwise)
 			/// 0xA9    -   Audio
 			/// 0xAA    -   Mode1
 			/// 0xAB    -   Mode2
@@ -271,6 +271,19 @@ namespace BizHawk.Emulation.DiscSystem
 			public int PSec;
 			public int PFrame;
 
+			/// <summary>
+			/// Lower 3 bits of ATrack Mode
+			/// Upper 5 bits are meaningless (see mirage_parser_mds_convert_track_mode)
+			/// 0x0 - None or Mode2 (Depends on sector size)
+			/// 0x1 - Audio
+			/// 0x2 - DVD or Mode1 (Depends on medium)
+			/// 0x3 - Mode2
+			/// 0x4 - Mode2 Form1
+			/// 0x5 - Mode2 Form2
+			/// 0x6 - UNKNOWN
+			/// 0x7 - Mode2
+			/// </summary>
+			public int TrackMode;
 
 			public int SectorSize;
 			public long TrackOffset;
@@ -313,6 +326,12 @@ namespace BizHawk.Emulation.DiscSystem
 				throw new MDSParseException($"MDS Parse Error: Only MDS version 1.x is supported!\nDetected version: {aFile.Header.Version[0]}.{aFile.Header.Version[1]}");
 			}
 
+			isDvd = aFile.Header.Medium is 0x10 or 0x12;
+			if (isDvd)
+			{
+				throw new MDSParseException("DVD Detected. Not currently supported!");
+			}
+
 			// parse sessions
 			var aSessions = new Dictionary<int, ASession>();
 
@@ -377,12 +396,6 @@ namespace BizHawk.Emulation.DiscSystem
 					track.Files = bc.ToInt32(trackHeader.Skip(48).Take(4).ToArray());
 					track.FooterOffset = bc.ToInt32(trackHeader.Skip(52).Take(4).ToArray());
 
-					if (track.Mode == 0x02)
-					{
-						isDvd = true;
-						throw new MDSParseException("DVD Detected. Not currently supported!");
-					}
-					
 					// check for track extra block - this can probably be handled in a separate loop,
 					// but I'll just store the current stream position then seek forward to the extra block for this track
 					var currPos = stream.Position;
@@ -484,8 +497,15 @@ namespace BizHawk.Emulation.DiscSystem
 
 					stream.Position = currPos;
 
+					var point = track.Point;
+					// each session has its own 0xA0/0xA1/0xA3 track
+					// so this can't be used directly as a key
+					if (point is 0xA0 or 0xA1 or 0xA2)
+					{
+						point |= session.SessionNumber << 8;
+					}
 
-					aTracks.Add(track.Point, track);
+					aTracks.Add(point, track);
 					aFile.Tracks.Add(track);
 
 					if (footerOffset == 0)
@@ -521,32 +541,57 @@ namespace BizHawk.Emulation.DiscSystem
 
 			// now build the TOC object
 			foreach (var se in aFile.ParsedSession)
-				foreach (var t in aTracks.Values
+			{
-					.Where(a => se.StartTrack <= a.TrackNo && a.TrackNo <= se.EndTrack)
+				ATOCEntry CreateTOCEntryFromTrack(ATrack track)
-					.OrderBy(a => a.TrackNo))
 				{
-					aFile.TOCEntries.Add(new(t.Point)
+					return new(track.Point)
 					{
-						ADR_Control = t.ADR_Control,
+						ADR_Control = track.ADR_Control,
-						AFrame = t.AFrame,
+						AFrame = track.AFrame,
-						AMin = t.AMin,
+						AMin = track.AMin,
-						ASec = t.ASec,
+						ASec = track.ASec,
-						BlobIndex = t.BlobIndex,
+						BlobIndex = track.BlobIndex,
-						EntryNum = t.TrackNo,
+						EntryNum = track.TrackNo,
-						ExtraBlock = t.ExtraBlock,
+						ExtraBlock = track.ExtraBlock,
-						ImageFileNamePaths = t.ImageFileNamePaths,
+						ImageFileNamePaths = track.ImageFileNamePaths,
-						PFrame = t.PFrame,
+						PFrame = track.PFrame,
-						PLBA = Convert.ToInt32(t.PLBA),
+						PLBA = Convert.ToInt32(track.PLBA),
-						PMin = t.PMin,
+						PMin = track.PMin,
-						Point = t.Point,
+						Point = track.Point,
-						PSec = t.PSec,
+						PSec = track.PSec,
-						SectorSize = t.SectorSize,
+						TrackMode = track.Mode & 0x7,
+						SectorSize = track.SectorSize,
 						Session = se.SessionSequence,
-						TrackOffset = Convert.ToInt64(t.StartOffset),
+						TrackOffset = Convert.ToInt64(track.StartOffset),
-						Zero = t.Zero
+						Zero = track.Zero
-					});
+					};
 				}
 
+				void AddAXTrack(int x)
+				{
+					if (aTracks.TryGetValue(se.SessionSequence << 8 | 0xA0 | x, out var axTrack))
+					{
+						aFile.TOCEntries.Add(CreateTOCEntryFromTrack(axTrack));
+					}
+				}
+
+				// add in the 0xA0/0xA1/0xA2 tracks
+				AddAXTrack(0);
+				AddAXTrack(1);
+				AddAXTrack(2);
+
+				// add in the rest of the tracks
+				foreach (var t in aTracks
+							.Where(a => se.StartTrack <= a.Key && a.Key <= se.EndTrack)
+							.OrderBy(a => a.Key)
+							.Select(a => a.Value))
+				{
+					aFile.TOCEntries.Add(CreateTOCEntryFromTrack(t));
+				}
+
+				// TODO: first session might have 0xB0/0xC0 tracks... not sure how to handle these
+			}
+
 			return aFile;
 		}
 
@@ -714,6 +759,32 @@ namespace BizHawk.Emulation.DiscSystem
 			var currBlobIndex = 0;
 			foreach (var session in mdsf.ParsedSession)
 			{
+				// leadin track
+				// we create this only for session 2+, not session 1
+				var leadinSize = session.SessionSequence == 1 ? 0 : 4500;
+				for (var i = 0; i < leadinSize; i++)
+				{
+					// this is most certainly wrong
+					// nothing relies on the exact contents for now (only multisession core is VirtualJaguar which doesn't touch leadin)
+					// just needs sectors to be present due to track info LBAs of session 2+ accounting for this being present
+					var pregapTrackType = CUE.CueTrackType.Audio;
+					if (tocSynth.Result.TOCItems[1].IsData)
+					{
+						pregapTrackType = tocSynth.Result.SessionFormat switch
+						{
+							SessionFormat.Type20_CDXA => CUE.CueTrackType.Mode2_2352,
+							SessionFormat.Type10_CDI => CUE.CueTrackType.CDI_2352,
+							SessionFormat.Type00_CDROM_CDDA => CUE.CueTrackType.Mode1_2352,
+							_ => pregapTrackType
+						};
+					}
+					disc._Sectors.Add(new CUE.SS_Gap()
+					{
+						Policy = IN_DiscMountPolicy,
+						TrackType = pregapTrackType
+					});
+				}
+
 				for (var i = session.StartTrack; i <= session.EndTrack; i++)
 				{
 					var relMSF = -1;
@@ -800,8 +871,6 @@ namespace BizHawk.Emulation.DiscSystem
 					var currBlobOffset = track.TrackOffset;
 					for (var sector = session.StartSector; sector <= session.EndSector; sector++)
 					{
-						CUE.SS_Base sBase;
-
 						// get the current blob from the BlobIndex
 						var currBlob = (Blob_RawFile) BlobIndex[currBlobIndex];
 						var currBlobLength = currBlob.Length;
@@ -809,33 +878,29 @@ namespace BizHawk.Emulation.DiscSystem
 							currBlobIndex++;
 						var mdfBlob = (IBlob) disc.DisposableResources[currBlobIndex];
 
-						//int userSector = 2048;
+						CUE.SS_Base sBase = track.SectorSize switch
-						switch (track.SectorSize)
 						{
-							case 2448:
+							2352 when track.TrackMode is 1 => new CUE.SS_2352(),
-								sBase = new CUE.SS_2352()
+							2048 when track.TrackMode is 2 => new CUE.SS_Mode1_2048(),
-								{
+							2336 when track.TrackMode is 0 or 3 or 7 => new CUE.SS_Mode2_2336(),
-									Policy = IN_DiscMountPolicy
+							2048 when track.TrackMode is 4 => new CUE.SS_Mode2_Form1_2048(),
-								};
+							2324 when track.TrackMode is 5 => new CUE.SS_Mode2_Form2_2324(),
-								//userSector = 2352;
+							2328 when track.TrackMode is 5 => new CUE.SS_Mode2_Form2_2328(),
-								break;
+							// best guesses
-							case 2048:
+							2048 => new CUE.SS_Mode1_2048(),
-							default:
+							2336 => new CUE.SS_Mode2_2336(),
-								sBase = new CUE.SS_Mode1_2048()
+							2352 => new CUE.SS_2352(),
-								{
+							2448 => new CUE.SS_2448_Interleaved(),
-									Policy = IN_DiscMountPolicy
+							_ => throw new InvalidOperationException($"Not supported: Sector Size {track.SectorSize}, Track Mode {track.TrackMode}")
-								};
+						};
-								//userSector = 2048;
+
-								break;
+						sBase.Policy = IN_DiscMountPolicy;
-							
-								//throw new Exception($"Not supported: Sector Size {track.SectorSize}");
-						}
 
 						// configure blob
 						sBase.Blob = mdfBlob;
 						sBase.BlobOffset = currBlobOffset;
 
-						currBlobOffset += track.SectorSize; // userSector;
+						currBlobOffset += track.SectorSize;
 						
 						// add subchannel data
 						relMSF++;
@@ -873,6 +938,18 @@ namespace BizHawk.Emulation.DiscSystem
 						disc._Sectors.Add(sBase);
 					}
 				}
+
+				// leadout track
+				// first leadout is 6750 sectors, later ones are 2250 sectors
+				var leadoutSize = session.SessionSequence == 1 ? 6750 : 2250;
+				for (var i = 0; i < leadoutSize; i++)
+				{
+					disc._Sectors.Add(new SS_Leadout
+					{
+						SessionNumber = session.SessionSequence,
+						Policy = IN_DiscMountPolicy
+					});
+				}
 			}
 
 			return disc;

src/BizHawk.Emulation.DiscSystem/Internal/Jobs/Synthesize_DiscTOC_From_RawTOCEntries_Job.cs

@@ -29,11 +29,8 @@ namespace BizHawk.Emulation.DiscSystem
 			Result.TOCItems[0].Control = 0;
 			Result.TOCItems[0].Exists = false;
 
-			//just in case this doesn't get set...
+			var minFoundTrack = 1;
-			Result.FirstRecordedTrackNumber = 0;
+			var maxFoundTrack = 1;
-			Result.LastRecordedTrackNumber = 0;
-
-			var maxFoundTrack = 0;
 
 			foreach (var te in Entries)
 			{
@@ -50,6 +47,7 @@ namespace BizHawk.Emulation.DiscSystem
 					case 255:
 						throw new InvalidOperationException("point == 255");
 					case <= 99:
+						minFoundTrack = Math.Min(minFoundTrack, point);
 						maxFoundTrack = Math.Max(maxFoundTrack, point);
 						Result.TOCItems[point].LBA = q.AP_Timestamp - 150; //RawTOCEntries contained an absolute time
 						Result.TOCItems[point].Control = q.CONTROL;
@@ -96,8 +94,7 @@ namespace BizHawk.Emulation.DiscSystem
 			}
 
 			//this is speculative:
-			//well, nothing to be done here..
+			if (Result.FirstRecordedTrackNumber == -1) { Result.FirstRecordedTrackNumber = minFoundTrack; }
-//			if (ret.FirstRecordedTrackNumber == -1) { }
 			if (Result.LastRecordedTrackNumber == -1) { Result.LastRecordedTrackNumber = maxFoundTrack; }
 			if (Result.SessionFormat == SessionFormat.None) Result.SessionFormat = SessionFormat.Type00_CDROM_CDDA;
 

src/BizHawk.Emulation.DiscSystem/Internal/SectorSynth.cs

@@ -50,7 +50,7 @@ namespace BizHawk.Emulation.DiscSystem
 		/// <summary>
 		/// The complete sector userdata (2352 bytes) is required
 		/// </summary>
-		UserComplete = 15,
+		UserComplete = (Header16 | User2048 | ECM288Complete),
 
 		/// <summary>
 		/// An alias for UserComplete

src/BizHawk.Emulation.DiscSystem/Internal/SynthUtils.cs

@@ -71,6 +71,30 @@ namespace BizHawk.Emulation.DiscSystem
 			buffer16[offset + 15] = mode;
 		}
 
+		/// <summary>
+		/// Synthesizes a Mode2 sector subheader
+		/// </summary>
+		public static void SectorSubHeader(byte[] buffer8, int offset, byte form)
+		{
+			// see mirage_sector_generate_subheader
+			for (var i = 0; i < 8; i++) buffer8[offset + i] = 0;
+			if (form == 2)
+			{
+				// these are just 0 in form 1
+				buffer8[offset + 2] = 0x20;
+				buffer8[offset + 5] = 0x20;
+			}
+		}
+
+		/// <summary>
+		/// Synthesizes the EDC checksum for a Mode 1 data sector (and puts it in place)
+		/// </summary>
+		public static void EDC_Mode1(byte[] buf2352, int offset)
+		{
+			var edc = ECM.EDC_Calc(buf2352, offset, 2064);
+			ECM.PokeUint(buf2352, offset + 2064, edc);
+		}
+
 		/// <summary>
 		/// Synthesizes the EDC checksum for a Mode 2 Form 1 data sector (and puts it in place)
 		/// </summary>
@@ -92,13 +116,12 @@ namespace BizHawk.Emulation.DiscSystem
 
 		/// <summary>
 		/// Synthesizes the complete ECM data (EDC + ECC) for a Mode 1 data sector (and puts it in place)
-		/// Make sure everything else in the sector userdata is done before calling this
+		/// Make sure everything else in the sector header and userdata is done before calling this
 		/// </summary>
-		public static void ECM_Mode1(byte[] buf2352, int offset, int LBA)
+		public static void ECM_Mode1(byte[] buf2352, int offset)
 		{
 			//EDC
-			var edc = ECM.EDC_Calc(buf2352, offset, 2064);
+			EDC_Mode1(buf2352, offset);
-			ECM.PokeUint(buf2352, offset + 2064, edc);
 
 			//reserved, zero
 			for (var i = 0; i < 8; i++) buf2352[offset + 2068 + i] = 0;
@@ -107,6 +130,37 @@ namespace BizHawk.Emulation.DiscSystem
 			ECM.ECC_Populate(buf2352, offset, buf2352, offset, false);
 		}
 
+		/// <summary>
+		/// Synthesizes the complete ECM data (Subheader + EDC + ECC) for a Mode 2 Form 1 data sector (and puts it in place)
+		/// Make sure everything else in the sector header and userdata is done before calling this
+		/// </summary>
+		public static void ECM_Mode2_Form1(byte[] buf2352, int offset)
+		{
+			//Subheader
+			SectorSubHeader(buf2352, offset + 16, 1);
+
+			//EDC
+			EDC_Mode2_Form1(buf2352, offset);
+
+			//ECC
+			ECM.ECC_Populate(buf2352, offset, buf2352, offset, false);
+		}
+
+		/// <summary>
+		/// Synthesizes the complete ECM data (Subheader + EDC) for a Mode 2 Form 2 data sector (and puts it in place)
+		/// Make sure everything else in the userdata is done before calling this
+		/// </summary>
+		public static void ECM_Mode2_Form2(byte[] buf2352, int offset)
+		{
+			//Subheader
+			SectorSubHeader(buf2352, offset + 16, 2);
+
+			//EDC
+			EDC_Mode2_Form2(buf2352, offset);
+
+			//note that Mode 2 Form 2 does not have ECC
+		}
+
 		/// <summary>
 		/// Converts the useful (but unrealistic) deinterleaved subchannel data into the useless (but realistic) interleaved format.
 		/// in_buf and out_buf should not overlap