Sanitize CP932 WAV metadata for Godot

engine/Age.Engine.Tests/RiffWaveSanitizerTests.cs

@@ -0,0 +1,94 @@
+using System.Buffers.Binary;
+using System.Text;
+using Age.Engine.Sys4;
+
+public class RiffWaveSanitizerTests
+{
+    [Fact]
+    public void RemovesOnlyInfoListAndPreservesFunctionalChunksAndPadding()
+    {
+        byte[] fmt = { 1, 0, 1, 0 };
+        byte[] info = { (byte)'I', (byte)'N', (byte)'F', (byte)'O',
+                        (byte)'I', (byte)'P', (byte)'R', (byte)'D',
+                        3, 0, 0, 0, 0x81, 0x45, 0 };
+        byte[] sampleLoop = { 9, 8, 7, 6 };
+        byte[] data = { 1, 2, 3 };
+        byte[] source = Wave(("fmt ", fmt), ("LIST", info), ("smpl", sampleLoop), ("data", data));
+
+        byte[] sanitized = RiffWaveSanitizer.RemoveInfoMetadata(source);
+
+        Assert.NotSame(source, sanitized);
+        Assert.Equal(sanitized.Length - 8, BinaryPrimitives.ReadInt32LittleEndian(sanitized.AsSpan(4, 4)));
+        Assert.Equal(new[] { "fmt ", "smpl", "data" }, ChunkIds(sanitized));
+        Assert.Equal(fmt, Chunk(sanitized, "fmt "));
+        Assert.Equal(sampleLoop, Chunk(sanitized, "smpl"));
+        Assert.Equal(data, Chunk(sanitized, "data"));
+    }
+
+    [Fact]
+    public void LeavesWaveWithoutInfoMetadataUnchanged()
+    {
+        byte[] source = Wave(("fmt ", new byte[] { 1, 0 }), ("data", new byte[] { 1, 2 }));
+
+        Assert.Same(source, RiffWaveSanitizer.RemoveInfoMetadata(source));
+    }
+
+    [Fact]
+    public void InstalledSc0000GlowSoundDropsCp932InfoBlockWithoutChangingPcmData()
+    {
+        var resources = ResourceMap.Load();
+        AudioPayload audio = resources.ReadAudio(resources.ResolveSoundEffect(0x28)!);
+
+        byte[] sanitized = RiffWaveSanitizer.RemoveInfoMetadata(audio.Bytes);
+
+        Assert.Equal("E0808.WAV", audio.Name);
+        Assert.Equal(688_570, audio.Bytes.Length);
+        Assert.Equal(688_336, sanitized.Length);
+        Assert.DoesNotContain("LIST", ChunkIds(sanitized));
+        Assert.Equal(Chunk(audio.Bytes, "data"), Chunk(sanitized, "data"));
+    }
+
+    private static byte[] Wave(params (string Id, byte[] Payload)[] chunks)
+    {
+        int length = 12 + chunks.Sum(chunk => 8 + chunk.Payload.Length + (chunk.Payload.Length & 1));
+        var result = new byte[length];
+        Encoding.ASCII.GetBytes("RIFF").CopyTo(result, 0);
+        BinaryPrimitives.WriteInt32LittleEndian(result.AsSpan(4, 4), length - 8);
+        Encoding.ASCII.GetBytes("WAVE").CopyTo(result, 8);
+        int offset = 12;
+        foreach (var chunk in chunks)
+        {
+            Encoding.ASCII.GetBytes(chunk.Id).CopyTo(result, offset);
+            BinaryPrimitives.WriteInt32LittleEndian(result.AsSpan(offset + 4, 4), chunk.Payload.Length);
+            chunk.Payload.CopyTo(result, offset + 8);
+            offset += 8 + chunk.Payload.Length + (chunk.Payload.Length & 1);
+        }
+        return result;
+    }
+
+    private static string[] ChunkIds(byte[] wave)
+    {
+        var ids = new List<string>();
+        int offset = 12;
+        while (offset < wave.Length)
+        {
+            ids.Add(Encoding.ASCII.GetString(wave, offset, 4));
+            int length = BinaryPrimitives.ReadInt32LittleEndian(wave.AsSpan(offset + 4, 4));
+            offset += 8 + length + (length & 1);
+        }
+        return ids.ToArray();
+    }
+
+    private static byte[] Chunk(byte[] wave, string wanted)
+    {
+        int offset = 12;
+        while (offset < wave.Length)
+        {
+            string id = Encoding.ASCII.GetString(wave, offset, 4);
+            int length = BinaryPrimitives.ReadInt32LittleEndian(wave.AsSpan(offset + 4, 4));
+            if (id == wanted) return wave.AsSpan(offset + 8, length).ToArray();
+            offset += 8 + length + (length & 1);
+        }
+        throw new InvalidDataException($"missing RIFF chunk {wanted}");
+    }
+}