Mp3读取，Effect Remove

Signed-off-by: TRAfoer <lhf190@outlook.com>

Assets/NLayer/Decoder/RiffHeaderFrame.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace NLayer.Decoder
+{
+    /// <summary>
+    /// RIFF header reader
+    /// </summary>
+    class RiffHeaderFrame : FrameBase
+    {
+        internal static RiffHeaderFrame TrySync(uint syncMark)
+        {
+            if (syncMark == 0x52494646U)
+            {
+                return new RiffHeaderFrame();
+            }
+
+            return null;
+        }
+
+        RiffHeaderFrame()
+        {
+
+        }
+
+        protected override int Validate()
+        {
+            var buf = new byte[4];
+
+            // we expect this to be the "WAVE" chunk
+            if (Read(8, buf) != 4) return -1;
+            if (buf[0] != 'W' || buf[1] != 'A' || buf[2] != 'V' || buf[3] != 'E') return -1;
+
+            // now the "fmt " chunk
+            if (Read(12, buf) != 4) return -1;
+            if (buf[0] != 'f' || buf[1] != 'm' || buf[2] != 't' || buf[3] != ' ') return -1;
+
+            // we've found the fmt chunk, so look for the data chunk
+            var offset = 16;
+            while (true)
+            {
+                // read the length and seek forward
+                if (Read(offset, buf) != 4) return -1;
+                offset += 4 + BitConverter.ToInt32(buf, 0);
+
+                // get the chunk ID
+                if (Read(offset, buf) != 4) return -1;
+                offset += 4;
+
+                // if it's not the data chunk, try again
+                if (buf[0] == 'd' && buf[1] == 'a' && buf[2] == 't' && buf[3] == 'a') break;
+            }
+
+            // ... and now we know exactly where the frame ends
+            return offset + 4;
+        }
+    }
+}