diff --git a/CdgLib/GraphicsFile.cs b/CdgLib/GraphicsFile.cs
new file mode 100644
index 0000000..332c847
--- /dev/null
+++ b/CdgLib/GraphicsFile.cs
@@ -0,0 +1,110 @@
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.IO;
+using System.Threading.Tasks;
+using CdgLib.SubCode;
+
+namespace CdgLib
+{
+    public class GraphicsFile : FileStream
+    {
+        private const int ColourTableSize = 16;
+
+        private const int CdgPacketSize = 24;
+        private const int TileHeight = 12;
+        private const int TileWidth = 6;
+        public const int FullWidth = 300;
+        public const int FullHeight = 216;
+
+        private readonly int[] _mColourTable = new int[ColourTableSize];
+        private readonly byte[,] _mPixelColours = new byte[FullHeight, FullWidth];
+
+
+        private long _previousPosition;
+
+        public GraphicsFile(string path, FileMode mode, FileAccess fileAccess) : base(path, mode, fileAccess, FileShare.Read)
+        {
+          
+        }
+
+        public bool Transparent => true;
+
+        public long Duration => Length/CdgPacketSize*1000/300;
+
+        public async Task<Bitmap> RenderAtTime(long position = -1)
+        {
+            if (position < 0)
+            {
+                position = _previousPosition + CdgPacketSize;
+            }
+
+            if (position < _previousPosition)
+            {
+               // Reset();
+            }
+
+            //duration of one packet is 1/300 seconds (4 packets per sector, 75 sectors per second)
+            //p=t*3/10  t=p*10/3 t=milliseconds, p=packets
+            var timeToRender = position - _previousPosition;
+            _previousPosition += timeToRender;
+            var numberOfSubCodePackets = timeToRender*3/10;
+      
+            var subCodePackets = await ReadSubCodeAsync(numberOfSubCodePackets);
+            foreach (var subCodePacket in subCodePackets)
+            {
+               // ProcessPacket(subCodePacket);
+            }
+            
+            RenderSurface();
+            
+
+
+        }
+
+
+
+        private async Task<IEnumerable<Packet>> ReadSubCodeAsync(long numberOfPackets)
+        {
+            var subCodePackets = new List<Packet>();
+            var buffer = new byte[CdgPacketSize*numberOfPackets];
+            var bytesRead = await ReadAsync(buffer, 0, buffer.Length);
+
+            for (var i = 0; i < bytesRead/CdgPacketSize; i++)
+            {
+                var subCodePacket = new Packet();
+                Array.Copy(buffer, i*CdgPacketSize + 0, subCodePacket.Command, 0, 1);
+                Array.Copy(buffer, i*CdgPacketSize + 1, subCodePacket.Instruction, 0, 1);
+                Array.Copy(buffer, i*CdgPacketSize + 2, subCodePacket.ParityQ, 0, 2);
+                Array.Copy(buffer, i*CdgPacketSize + 4, subCodePacket.Data, 0, 16);
+                Array.Copy(buffer, i*CdgPacketSize + 20, subCodePacket.ParityP, 0, 4);
+                subCodePackets.Add(subCodePacket);
+            }
+            return subCodePackets;
+        }
+
+
+
+        private void RenderSurface()
+        {
+            if (_mPSurface == null)
+                return;
+            for (var ri = 0; ri <= FullHeight - 1; ri++)
+            {
+                for (var ci = 0; ci <= FullWidth - 1; ci++)
+                {
+                    if (ri < TileHeight || ri >= FullHeight - TileHeight || ci < TileWidth ||
+                        ci >= FullWidth - TileWidth)
+                    {
+                     //   _mPSurface.RgbData[ri, ci] = _mColourTable[_mBorderColourIndex];
+                    }
+                    else
+                    {
+                        _mPSurface.RgbData[ri, ci] = _mColourTable[_mPixelColours[ri + _mVOffset, ci + _mHOffset]];
+                    }
+                }
+            }
+        }
+    }
+}
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