add subtitle language detection

Emby.Common.Implementations/TextEncoding/NLangDetect/LanguageDetector.cs

@@ -0,0 +1,37 @@
+using System;
+using MediaBrowser.Model.Serialization;
+
+namespace NLangDetect.Core
+{
+    // TODO IMM HI: change to non-static class
+    // TODO IMM HI: hide other, unnecassary classes via internal?
+    public static class LanguageDetector
+    {
+        private const double _DefaultAlpha = 0.5;
+
+        #region Public methods
+
+        public static void Initialize(IJsonSerializer json)
+        {
+            DetectorFactory.LoadProfiles(json);
+        }
+
+        public static void Release()
+        {
+            DetectorFactory.Clear();
+        }
+
+        public static string DetectLanguage(string plainText)
+        {
+            if (string.IsNullOrEmpty(plainText)) { throw new ArgumentException("Argument can't be null nor empty.", "plainText"); }
+
+            Detector detector = DetectorFactory.Create(_DefaultAlpha);
+
+            detector.Append(plainText);
+
+            return detector.Detect();
+        }
+
+        #endregion
+    }
+}