using System;

using System.Collections.Generic;

using System.IO;

​

namespace FragmentarUnirAchivo

{

    class Program

    {

        public static void Main()

        {

            Console.WriteLine("Hello World");

            var t = DateTime.Now;

            var sourceFilename = @"D:\code\PeruCIM\ci2.platinocim\src\Ci2.PeruCim.Web\VideosEditados\AMA401_2019-03-20T19-50-36.617Z_000000010619.mp4";

            var targetFilename = @"D:\code\PeruCIM\ci2.platinocim\src\Ci2.PeruCim.Web\VideosEditados\copiado.mp4";

​

            var bufferSize = 1024 * 1000;

            var offset = 0;

            var bytes = ReadBytes(sourceFilename);

​

            while (offset < bytes.Length)

            {

                var buffer = Slice(bytes, offset, bufferSize);

                if ( buffer.Length>0)

                {

                    Transmit(targetFilename, buffer.ToArray());

                }

​

                offset += bufferSize;

            }

            Console.WriteLine($"Tiempo de copiado : {(DateTime.Now-t).TotalSeconds} segundos" );

        }

​

        private static void Transmit(string targetFilename, byte[] buffer)

        {

            using (FileStream target = new FileStream(targetFilename, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))

            {

                target.Position= target.Length;

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

            }

​

        }

​

        private static Span<byte> ReadBytes(string sourceFilename)

        {

            using (Stream from = new FileStream(sourceFilename, FileMode.Open, FileAccess.Read))

            {

                Span<byte> buffer = new byte[from.Length];                

                var read = from.Read(buffer);

                return buffer;

            }

​

        }

​

        private static Span<byte> Slice(Span<byte> buffer, int start, int length)

        {

            if (start >= buffer.Length) return new Span<byte>(new byte[0]);

            if (start + length > buffer.Length) length = buffer.Length - start;

​

            return buffer.Slice(start, length);

        }

    }

}

/*

https://adamsitnik.com/Span/

byte[] buffer = ArrayPool<byte>.Shared.Rent(16000 * 8); // we use an Array here, not Span

​

while ((bytesRead = await fileStream.ReadAsync(buffer, 0, buffer.Length)) > 0) // AWAIT! writing to array

{

    ParseBlock(new ReadOnlyMemory<byte>(buffer, start: 0, length: bytesRead)); // creating ReadOnlyMemory which points to managed array

}

​

void ParseBlock(ReadOnlyMemory<byte> memory)

{

    ReadOnlySpan<byte> slice = memory.Span; // using Span from here

}

*/

​