using System;

using System.IO;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        String image64 = "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";

        //

        byte [] buffer = Convert.FromBase64String(image64);

        //

        using(FileStream fs = new FileStream("a.bin", FileMode.Create))

        {

        fs.Write (buffer,0,buffer.Length) ;

        }

        //

        byte [] imageBuffer = new byte [1024*1024*16]; // 16 MB

        int imageSize = 0;

        using(FileStream reader = new FileStream("a.bin",FileMode.Open, FileAccess.Read))

        {           

            byte [] readBuffer = new byte [1024];

            while ( true )

            {

                int readCount = reader.Read(readBuffer,0,readBuffer.Length);

                if ( readCount <1)

                    break ;

                //

                Buffer.BlockCopy(readBuffer,0,imageBuffer,imageSize,readCount);

                imageSize += readCount ;

            }

        }

        //

        Console.WriteLine("imageBuffer Length:" + imageSize + " / " + buffer.Length);

        //      

        String image64V2 = Convert.ToBase64String (imageBuffer,0,imageSize);

        //

        Console.WriteLine("Is test ok ? " + image64V2.Equals(image64) );

        Console.WriteLine(image64V2);

        //

    }

}