Move movie runtime support to frontend

2026-08-03 11:29:47 -04:00
parent 511badae6d
commit c5d32b600f
9 changed files with 22 additions and 14 deletions
--- a/engine/Age.Engine.Frontend/RiffWaveSanitizer.cs
+++ b/engine/Age.Engine.Frontend/RiffWaveSanitizer.cs
@@ -0,0 +1,72 @@
+using System;
+using System.Buffers.Binary;
+
+/// <summary>Godot-specific WAV input adapter. Native AGE decodes only the first declared RIFF/WAVE
+/// extent, while Godot walks the entire supplied buffer. AGE's Japanese assets also commonly store
+/// CP932 strings in INFO metadata that Godot assumes is UTF-8. Prepare a transient decoder copy that
+/// follows AGE's first-RIFF boundary and removes only INFO metadata within it.</summary>
+internal static class RiffWaveSanitizer
+{
+    public static byte[] PrepareForGodot(byte[] wavBytes)
+    {
+        ReadOnlySpan<byte> input = wavBytes;
+        if (input.Length < 12 || !HasId(input, 0, "RIFF") || !HasId(input, 8, "WAVE"))
+            return wavBytes;
+
+        ulong declaredEnd64 = 8UL + BinaryPrimitives.ReadUInt32LittleEndian(input.Slice(4, 4));
+        if (declaredEnd64 < 12 || declaredEnd64 > (ulong)input.Length || declaredEnd64 > int.MaxValue)
+            return wavBytes;
+        int declaredEnd = (int)declaredEnd64;
+
+        int cursor = 12;
+        int removedBytes = 0;
+        while (cursor < declaredEnd)
+        {
+            if (!TryGetChunk(input, cursor, declaredEnd, out int chunkBytes, out bool isInfoList))
+                return wavBytes;
+            if (isInfoList) removedBytes = checked(removedBytes + chunkBytes);
+            cursor += chunkBytes;
+        }
+        if (removedBytes == 0 && declaredEnd == wavBytes.Length) return wavBytes;
+
+        int newDeclaredEnd = checked(declaredEnd - removedBytes);
+        var output = new byte[newDeclaredEnd];
+        input[..12].CopyTo(output);
+        cursor = 12;
+        int destination = 12;
+        while (cursor < declaredEnd)
+        {
+            _ = TryGetChunk(input, cursor, declaredEnd, out int chunkBytes, out bool isInfoList);
+            if (!isInfoList)
+            {
+                input.Slice(cursor, chunkBytes).CopyTo(output.AsSpan(destination));
+                destination += chunkBytes;
+            }
+            cursor += chunkBytes;
+        }
+
+        BinaryPrimitives.WriteUInt32LittleEndian(output.AsSpan(4, 4),
+            checked((uint)(newDeclaredEnd - 8)));
+        return output;
+    }
+
+    private static bool TryGetChunk(ReadOnlySpan<byte> input, int offset, int declaredEnd,
+                                    out int chunkBytes, out bool isInfoList)
+    {
+        chunkBytes = 0;
+        isInfoList = false;
+        if (offset > declaredEnd - 8) return false;
+        uint payloadBytes = BinaryPrimitives.ReadUInt32LittleEndian(input.Slice(offset + 4, 4));
+        ulong total64 = 8UL + payloadBytes + (payloadBytes & 1U);
+        if (total64 > int.MaxValue || total64 > (ulong)(declaredEnd - offset)) return false;
+        chunkBytes = (int)total64;
+        isInfoList = payloadBytes >= 4 && HasId(input, offset, "LIST")
+                    && HasId(input, offset + 8, "INFO");
+        return true;
+    }
+
+    private static bool HasId(ReadOnlySpan<byte> bytes, int offset, string id)
+        => offset >= 0 && offset <= bytes.Length - 4
+           && bytes[offset] == id[0] && bytes[offset + 1] == id[1]
+           && bytes[offset + 2] == id[2] && bytes[offset + 3] == id[3];
+}