(VnMaker): Add support of ZIP MP3 OGG PNG formats.

ArcFormats/VnMaker/AudioOGG.cs

@@ -0,0 +1,40 @@
+using System.ComponentModel.Composition;
+
+namespace GameRes.Formats.VnMaker
+{
+    [Export(typeof(AudioFormat))]
+    public class AudioOGG : AudioFormat
+    {
+        public override string         Tag { get { return "OGG/VnMaker Encrypted OGG Audio"; } }
+        public override string Description { get { return "VnMaker Encrypted OGG Audio"; } }
+        public override uint     Signature { get { return 0; } }
+        public override bool      CanWrite { get { return false; } }
+
+        public AudioOGG() : base()
+        {
+            Signatures = new uint[] { 0 };
+            Extensions = new[] { "ogg" };
+        }
+
+        public override SoundInput TryOpen (IBinaryStream file)
+        {
+            using (var input = DeobfuscateStream (file, GuessEncryptionKey (file)))
+            {
+                if (input.Signature != 0x5367674F)
+                    throw new InvalidFormatException ();
+                return new OggInput (input.AsStream);
+            }
+        }
+
+        byte[] GuessEncryptionKey (IBinaryStream file)
+        {
+            return new byte[] { 0x0A, 0x2B, 0x36, 0x6F, 0x0B };
+        }
+
+        IBinaryStream DeobfuscateStream (IBinaryStream file, byte[] key)
+        {
+            var ogg = new ByteStringEncryptedStream (file.AsStream, key, true);
+            return new BinaryStream (ogg, file.Name);
+        }
+    }
+}