Question

Im a newbie to TCPClient, Im trying to make a webcam app that sends small images ~4kb each to another IP which will run an identical program. So its going to send and receive at the same time.

Problem I have is the _tcpOut disconnects after one send which means I only see one frame. In the code below there are two sections, first the NewFrameReceived is run on every new image from the camera, which is then sent, the other method is the receive method which puts the received pic into a picture box (at the moment my own from 127.0.0.1) :

private void fChat_Load(object sender, EventArgs e)
{
   // fire up listener
   listeningThread.RunWorkerAsync();

   // tcp server setup
   _tcpOut = new TcpClient();
   _tcpOut.Connect("127.0.0.1", 54321);
}


    private void NewFrameReceived(object sender, NewFrameEventArgs e)
    {
        Bitmap img = (Bitmap)e.Frame.Clone();

        byte[] imgBytes = EncodeToJpeg(img, 25).ToArray();
        if (_tcpOut.Connected) <-- PROBLEM HERE, THIS IS FALSE ON 2ND ITERATION
        {
            using (NetworkStream ns = _tcpOut.GetStream())
            {
                if (ns.CanWrite)
                {
                    ns.Write(BitConverter.GetBytes(imgBytes.Length), 0, 4);
                    ns.Write(imgBytes, 0, imgBytes.Length);
                }
            }
        }
    }


    private void listeningThread_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
    {
        // start listening for connections
        _tcpIn = new TcpListener(IPAddress.Any, 54321);
        _tcpIn.Start();

        while (true)
        {
            using (TcpClient _inClient = _tcpIn.AcceptTcpClient()) // blocks until connected
            {
                using (NetworkStream stream = _inClient.GetStream())
                {
                    Byte[] imgSizeBytes = new Byte[4];
                    stream.Read(imgSizeBytes, 0, 4);
                    int imgSize = BitConverter.ToInt32(imgSizeBytes, 0);
                    Byte[] imgBytes = new Byte[imgSize];
                    stream.Read(imgBytes, 0, imgSize);
                    MemoryStream ms = new MemoryStream(imgBytes);
                    Image img = Image.FromStream(ms);
                    picVideo.Image = img;
                }
            }
        }
    }

Many thanks in advance.

Answer 1

It disconnects because you’re disposing the TcpClient with the using statement.