Better handle invalid banks, support multi-sample banks + sample names

Author: SamboyCoding

Fmod5Sharp/Fmod5Sharp.csproj

@@ -19,6 +19,7 @@
     </PropertyGroup>
 
     <ItemGroup>
+      <PackageReference Include="IndexRange" Version="1.0.2" />
       <PackageReference Include="NAudio.Core" Version="2.1.0" />
       <PackageReference Include="OggVorbisEncoder" Version="1.2.0" />
       <PackageReference Include="System.Text.Json" Version="6.0.5" />

Fmod5Sharp/FmodTypes/FmodAudioHeader.cs

@@ -9,36 +9,50 @@ namespace Fmod5Sharp.FmodTypes
 	public class FmodAudioHeader
 	{
 		private static readonly object ChunkReadingLock = new();
+
+		internal readonly bool IsValid;
 
-		public FmodAudioType AudioType;
-		public uint Version;
-		public uint NumSamples;
+		public readonly FmodAudioType AudioType;
+		public readonly uint Version;
+		public readonly uint NumSamples;
+
+		internal readonly uint SizeOfThisHeader;
+		internal readonly uint SizeOfSampleHeaders;
+		internal readonly uint SizeOfNameTable;
+		internal readonly uint SizeOfData;
 
-		internal uint DataSize;
-		internal List<FmodSampleMetadata> Samples = new();
+		internal readonly List<FmodSampleMetadata> Samples = new();
 
 		public FmodAudioHeader(BinaryReader reader)
 		{
 			string magic = reader.ReadString(4);
 
 			if (magic != "FSB5")
 			{
+				IsValid = false;
 				return;
 			}
 
 			Version = reader.ReadUInt32(); //0x04
 			NumSamples = reader.ReadUInt32(); //0x08
-			var sizeOfSampleHeaders = reader.ReadUInt32(); //0x0C
-			var nameTableSize = reader.ReadUInt32(); //0x10
-			DataSize = reader.ReadUInt32(); //0x14
+			SizeOfSampleHeaders = reader.ReadUInt32();
+			SizeOfNameTable = reader.ReadUInt32();
+			SizeOfData = reader.ReadUInt32(); //0x14
 			AudioType = (FmodAudioType) reader.ReadUInt32(); //0x18
+
+			reader.ReadUInt32(); //Skip 0x1C which is always 0
 
 			if (Version == 0)
 			{
-				reader.ReadUInt32(); //Version 0 has an extra field at 0x1C
+				SizeOfThisHeader = 0x40;
+				reader.ReadUInt32(); //Version 0 has an extra field at 0x20 before flags
+			}
+			else
+			{
+				SizeOfThisHeader = 0x3C;
 			}
 
-			reader.ReadUInt64(); //Skip 0x1C (zero) and 0x20 (flags)
+			reader.ReadUInt32(); //Skip 0x20 (flags)
 
 			//128-bit hash
 			var hashLower = reader.ReadUInt64(); //0x24
@@ -81,14 +95,8 @@ public FmodAudioHeader(BinaryReader reader)
 					Samples.Add(sampleMetadata);
 				}
 			}
-
-			var actualSampleHeadersLength = reader.Position() - sampleHeadersStart;
-
-			if (actualSampleHeadersLength != sizeOfSampleHeaders)
-			{
-				//Skip zero-padding so we're in the right place for data.
-				reader.ReadBytes((int)(sizeOfSampleHeaders - actualSampleHeadersLength));
-			}
+			
+			IsValid = true;
 		}
 	}
 }

Fmod5Sharp/FmodTypes/FmodSample.cs

@@ -7,6 +7,7 @@ public class FmodSample
     {
         public FmodSampleMetadata Metadata;
         public byte[] SampleBytes;
+        public string? Name;
         internal FmodSoundBank? MyBank;
 
         public FmodSample(FmodSampleMetadata metadata, byte[] sampleBytes)

Fmod5Sharp/FmodTypes/FmodSampleMetadata.cs

@@ -10,20 +10,28 @@ public class FmodSampleMetadata : IBinaryReadable
 		internal uint FrequencyId;
 		internal ulong DataOffset;
 		internal List<FmodSampleChunk> Chunks = new();
+		internal int NumChannels;
 
 		public bool IsStereo;
 		public ulong SampleCount;
+
 		public int Frequency => FsbLoader.Frequencies.TryGetValue(FrequencyId, out var actualFrequency) ? actualFrequency : (int)FrequencyId; //If set by FREQUENCY chunk, id is actual frequency
-		public uint Channels => IsStereo ? 2u : 1u;
+		public uint Channels => (uint)NumChannels;
 
 		void IBinaryReadable.Read(BinaryReader reader)
 		{
 			var encoded = reader.ReadUInt64();
 
-			HasAnyChunks = (encoded & 1) == 1;
-			FrequencyId = (uint) encoded.Bits(1, 4);
-			IsStereo = encoded.Bits(5, 1) == 1;
-			DataOffset = encoded.Bits(6, 28) * 16;
+			HasAnyChunks = (encoded & 1) == 1; //Bit 0
+			FrequencyId = (uint) encoded.Bits( 1, 4); //Bits 1-4
+			var pow2 = (int) encoded.Bits(5, 2); //Bits 5-6
+			NumChannels = 1 << pow2;
+			if (NumChannels > 2)
+				throw new("> 2 channels not supported");
+			
+			IsStereo = NumChannels == 2;
+			
+			DataOffset = encoded.Bits(7, 27) * 32;
 			SampleCount = encoded.Bits(34, 30);
 		}
 	}

Fmod5Sharp/FsbLoader.cs

@@ -1,60 +1,85 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using Fmod5Sharp.FmodTypes;
 using Fmod5Sharp.Util;
 
 namespace Fmod5Sharp
 {
-	public static class FsbLoader
-	{
-		internal static readonly Dictionary<uint, int> Frequencies = new()
-		{
-			{ 1, 8000 },
-			{ 2, 11_000 },
-			{ 3, 11_025 },
-			{ 4, 16_000 },
-			{ 5, 22_050 },
-			{ 6, 24_000 },
-			{ 7, 32_000 },
-			{ 8, 44_100 },
-			{ 9, 48_000 },
-			{ 10, 96_000 },
-		};
-
-		public static FmodSoundBank LoadFsbFromByteArray(byte[] bankBytes)
-		{
-			using MemoryStream stream = new(bankBytes);
-			using BinaryReader reader = new(stream);
-
-			FmodAudioHeader header = new(reader);
-
-			List<FmodSample> samples = new();
-
-			//Remove header from data block.
-			bankBytes = bankBytes.Skip((int)reader.Position()).ToArray();
-			
-			for (var i = 0; i < header.Samples.Count; i++)
-			{
-				FmodSampleMetadata sampleMetadata = header.Samples[i];
-
-				var firstByteOfSample = sampleMetadata.DataOffset;
-				ulong lastByteOfSample = header.DataSize;
-
-				if (i < header.Samples.Count - 1)
-				{
-					lastByteOfSample = header.Samples[i + 1].DataOffset;
-				}
-
-				samples.Add(
-					new FmodSample(
-						sampleMetadata,
-						bankBytes.Skip((int)firstByteOfSample).Take((int)(lastByteOfSample - firstByteOfSample)).ToArray()
-					)
-				);
-			}
-
-			return new FmodSoundBank(header, samples);
-		}
-	}
+    public static class FsbLoader
+    {
+        internal static readonly Dictionary<uint, int> Frequencies = new()
+        {
+            { 1, 8000 },
+            { 2, 11_000 },
+            { 3, 11_025 },
+            { 4, 16_000 },
+            { 5, 22_050 },
+            { 6, 24_000 },
+            { 7, 32_000 },
+            { 8, 44_100 },
+            { 9, 48_000 },
+            { 10, 96_000 },
+        };
+        
+        private static FmodSoundBank? LoadInternal(byte[] bankBytes, bool throwIfError)
+        {
+            using MemoryStream stream = new(bankBytes);
+            using BinaryReader reader = new(stream);
+
+            FmodAudioHeader header = new(reader);
+
+            if (!header.IsValid)
+            {
+                if (throwIfError)
+                    throw new("File is probably not an FSB file (magic number mismatch)");
+
+                return null;
+            }
+
+            List<FmodSample> samples = new();
+
+            //Remove header from data block.
+            var bankData = bankBytes.AsSpan((int)(header.SizeOfThisHeader + header.SizeOfNameTable + header.SizeOfSampleHeaders));
+
+            for (var i = 0; i < header.Samples.Count; i++)
+            {
+                var sampleMetadata = header.Samples[i];
+
+                var firstByteOfSample = (int)sampleMetadata.DataOffset;
+                var lastByteOfSample = (int)header.SizeOfData;
+
+                if (i < header.Samples.Count - 1)
+                {
+                    lastByteOfSample = (int)header.Samples[i + 1].DataOffset;
+                }
+
+                var sample = new FmodSample(sampleMetadata, bankData[firstByteOfSample..lastByteOfSample].ToArray());
+
+                if (header.SizeOfNameTable > 0)
+                {
+                    var nameOffsetOffset = header.SizeOfThisHeader + header.SizeOfSampleHeaders + 4 * i;
+                    reader.BaseStream.Position = nameOffsetOffset;
+                    var nameOffset = reader.ReadUInt32();
+
+                    nameOffset += header.SizeOfThisHeader + header.SizeOfSampleHeaders;
+
+                    sample.Name = bankBytes.ReadNullTerminatedString((int)nameOffset);
+                }
+
+                samples.Add(sample);
+            }
+
+            return new FmodSoundBank(header, samples);
+        }
+
+        public static bool TryLoadFsbFromByteArray(byte[] bankBytes, out FmodSoundBank? bank)
+        {
+            bank = LoadInternal(bankBytes, false);
+            return bank != null;
+        }
+
+        public static FmodSoundBank LoadFsbFromByteArray(byte[] bankBytes)
+            => LoadInternal(bankBytes, true)!;
+    }
 }

Fmod5Sharp/Util/Extensions.cs

@@ -1,4 +1,5 @@
-using System.IO;
+using System;
+using System.IO;
 using System.Text;
 
 namespace Fmod5Sharp.Util
@@ -39,5 +40,14 @@ internal static ulong Bits(this ulong raw, int lowestBit, int numBits)
 
             return (raw & mask) >> lowestBit;
         }
+
+        internal static string ReadNullTerminatedString(this byte[] bytes, int startOffset)
+        {
+            var strLen = bytes.AsSpan(startOffset).IndexOf((byte)0);
+            if (strLen == -1)
+                throw new("Could not find null terminator");
+            
+            return Encoding.UTF8.GetString(bytes, startOffset, strLen);
+        }
     }
 }