C＃使用TCP读取IP摄像机的所有数据

Question

I have IP camera and I have problem to read image data from this camera. To read image I have to send command to camera and read: 1) Length Of Telegram 2) Response ID Get Image 3) Error Code 4) Image type 5) Image results 6) Number of rows, columns 7) Image data

To read data form point 1 to 6 is no problem because this is only 14 bytes. In point 6 I read the size of image. For example let number of rows and columns will be 640x480 so we have 307200 bytes.

To read image I am using Visual Studio 2010 and WindowsForm Application and action form button:

private void butReadImage_Click(object sender, EventArgs e)
{
     // code to read data from point 1 to 6
     // start read data image (point 7)

}

In butReadImage_Click I can read only 7000 bytes of image data because camera do not send all image data in one package. To read all data I enable timer (1ms interval) in butReadImage_Click an then using

     private void timReadImage_Tick(object sender, EventArgs e)
     {
            // read rest data form camera, about two data packets
            int numberOfBytesRead;
            while (rwSensorStream.DataAvailable)
            {
                numberOfBytesRead = rwSensorStream.Read(BinaryImageData_Byte_14_n, 0, BinaryImageData_Byte_14_n.Length);
                tempRC = tempRC + numberOfBytesRead;

                for (int i = 0; i < numberOfBytesRead; i++)
                {
                    image.Add(BinaryImageData_Byte_14_n[i]);
                }
            }
     }

I now that this is bad code using Timer. Does anyone have an idea how to read all data sent in several packages?.

Answer 1

Read the data asynchronously. You will have to figure out what the while loop conditional should be to loop the correct number of times for a single image, but awaiting ReadAsync to get data from your stream will allow your code to wait for a complete transmission before continuing.

public async Task getData(NetworkStream rwSensorStream) {
    while (true) {
        byte[ ] buffer = new byte[numberOfBytesAtOnce];
        int read = await rwSensorStream.ReadAsync(buffer, 0, buffer.Length); 
        //wait for next package

        if (read > 0) {
          // data received, process it 
        } 
        else break;  // will occur when connection is broken
    }
}