make a voice call c# using at command and NAudio lib

Question

I am trying to making a call using AT command and Naudio LIB to send and receive a voice to the modem and the incoming voice to the modem working fine but outgoing voice is muddled(noisy)

Any help is appreciated.

Here is the code:

 WaveIn waveSource;
    SerialPort portsend      = new SerialPort("COM20", 57600, Parity.None , 8 , StopBits.One); 
    SerialPort portReceived  = new SerialPort("COM19", 57600, Parity.None , 8 , StopBits.One);
    WaveOut waveOut = new WaveOut();
    WaveFormat format = new WaveFormat(8000, 16,1);

    // button call number
 private void button1_Click(object sender, EventArgs e)
        {
        waveSource = new WaveIn(this.Handle);
        waveSource.WaveFormat = new WaveFormat(8000,16, 1);
        waveSource.DataAvailable += new EventHandler<WaveInEventArgs>(waveSource_DataAvailable);


        waveOut.DesiredLatency = 100;

        portReceived.Open();
        portsend.Open();
        portsend.ReadTimeout = SerialPort.InfiniteTimeout; 
        portsend.WriteLine("ATZ;" + Environment.NewLine);
        Thread.Sleep(1000);
        portsend.WriteLine("ATD01271698522;" + Environment.NewLine);
        portReceived.DataReceived += new SerialDataReceivedEventHandler(modemPort_DataReceived); // received the binary of voice come from the modem 
        Thread.Sleep(1000); 
        portsend.Write("AT^DDSETEX=2" + Environment.NewLine);
        waveSource.StartRecording();
    }

    int i = 0;
    byte[] buffer;
    private BufferedWaveProvider _bufferedWaveProvider = new BufferedWaveProvider(new WaveFormat(16000, 16,1));

    void modemPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs args) 
    {
        int x = portReceived.BytesToRead;
        buffer = new byte[x];
        portReceived.Read(buffer, 0, x);
        _bufferedWaveProvider.AddSamples(buffer, 0, x);

        if(i==0)
        {       
            waveOut.Init(_bufferedWaveProvider);
        }

        waveOut.Play();

        ++i;
    }

    private void button2_Click(object sender, EventArgs e)
    {
        portsend.Close();
        portReceived.Close();


    }

    void waveSource_DataAvailable(object sender, WaveInEventArgs e)
    {
        portReceived.Write(e.Buffer, 0, e.BytesRecorded); // send the voice from mic to the modem 
    }

Answer 1

You're sending to yourself, correct? If so, how have you determined that incoming voice is fine, but outgoing is muddy? Wouldn't it all be muddy?

This is basically just a streaming data application, and the data just happens to be PCM audio. The fact that it's a serial port isn't really relevant (except to ensure that you have enough bps to support the audio rate).

Here's something I noticed. On the microphone input side, you have:

    waveSource = new WaveIn(this.Handle);
    waveSource.WaveFormat = new WaveFormat(8000,16, 1);
    waveSource.DataAvailable += new EventHandler<WaveInEventArgs>(waveSource_DataAvailable);

However, on the speaker output side, you have:

private BufferedWaveProvider _bufferedWaveProvider = new BufferedWaveProvider(new WaveFormat(16000, 16,1));

...

    if(i==0)
    {       
        waveOut.Init(_bufferedWaveProvider);
    }

    waveOut.Play();

    ++i;
}

First point: You should initialize the BufferedWaveProvider with the same WaveFormat you're using for the input.

Second point: Move the `waveOut.Play()' into the block above it, as follows:

    if(i==0)
    {       
        waveOut.Init(_bufferedWaveProvider);
        waveOut.Play();
    }

    ++i;

The way your code currently sits, you're calling waveOut.Play() every time you get new data on the serial port. That's not going to work very well!