获取文件数据流+叠加byte数组（给byte数组加包头包尾）

 OpenFileDialog ofd = new OpenFileDialog();
             ofd.Filter = "(*.mp4)|*.mp4|(*.*)|*.*";
             ofd.RestoreDirectory = true;
             if (ofd.ShowDialog() == DialogResult.OK)
             {
                 try
                 { // 打开文件 

                     FileStream fileStream = new FileStream(ofd.FileName, FileMode.Open, FileAccess.Read, FileShare.Read);

                     // 读取文件的 byte[] 

                     byte[] brecord = new byte[fileStream.Length];
                     fileStream.Read(brecord, , brecord.Length);
                     byte[] data1 = { , , , , , ,  };
                     byte[] data2 = { , , , , , ,  };

                     var data3 = new byte[data1.Length + data2.Length + brecord.Length];
                     Stream s = new MemoryStream();
                     s.Write(data1, , data1.Length);
                     s.Write(brecord, , brecord.Length);
                     s.Write(data2, , data2.Length);
                     s.Position = ;
                     int r = s.Read(data3, , data3.Length);
                     if (r > )
                     {
                         //此时data3中就是合并的值了
                     }
                     mc.Send(data3);

                     fileStream.Close();
                 }
                 catch (Exception ex)
                 {
                     MessageBox.Show(ex.Message.ToString());
                 }
                 finally
                 {
                     //sr.Close();
                     //fs.Close();
                 }
             }