Initial check-in

_Demos/ffmpeg decrypt/Extensions.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Windows.Forms;
+
+namespace ffmpeg_decrypt
+{
+	public static class StringExt
+    {
+        public static string SurroundWithQuotes(this string str) => "\"" + str + "\"";
+
+        public static string ExtractString(this string haystack, string before, int needleLength)
+        {
+            var index = haystack.IndexOf(before);
+            var needle = haystack.Substring(index + before.Length, needleLength);
+
+            return needle;
+        }
+    }
+
+    public static class ControlExt
+    {
+        /// <summary>
+        /// Executes the Action asynchronously on the UI thread, does not block execution on the calling thread.
+        /// </summary>
+        /// <param name="control"></param>
+        /// <param name="code"></param>
+        public static void UIThread(this Control control, Action code)
+        {
+            if (control.InvokeRequired)
+                control.BeginInvoke(code);
+            else
+                code.Invoke();
+        }
+    }
+}