[Freeswitch-users] Unicast isn't working

Артем Васильев ryder86 at googlemail.com
Tue May 26 01:27:16 PDT 2009


I am trying to setup ASR in FreeSwitch using Nuance ASR server and MRCP.
Both FreeSwitch and Nuance installed on Windows Server 2003. FreeSwitch
version is 1.0.3 (12567M)

I found an example in Perl at
http://www.softivr.com/wiki/index.php/FreeSWITCH_MRCP_in_Perl and decided to
do the same in C#.
It establishes connection with Nuance and loads the grammar, everything
works fine. The next step is to capture audio from FS and tramsmit it to
ASR. This can be done with unicast. We must create an outbound socket and
issue "unicast" command. Here it goes:

private void SetupAudioTransmission()
 EventSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream,
 EventSocket.SendTimeout = Config.Timeout;
 int ESPort = SearchESPort(EventSocket);

 Thread thrESListener = new Thread(new ThreadStart(ListenerThreadStart));

 WriteLog(LogLevel.Info, "Creating outbound event socket");
 Session.Execute("socket", "" + ESPort); //main thread stops,
listener thread listens for outbound socket connection.
 WriteLog(LogLevel.Info, "Outbound event socket disconnected");


//here we accept outbound socket and transmit unicast command through it
private void ListenerThreadStart()
 Socket sockHandler = EventSocket.Accept();
 WriteLog(LogLevel.Info, "Incoming connection");

 WriteLog(LogLevel.Info, GetServerResponse(sockHandler));

 int rtpPort = (RTPSocket.RemoteEndPoint as IPEndPoint).Port;
 string command = string.Format("sendmsg\r\ncall-command:
unicast\r\nlocal-ip: {0}\r\nlocal-port: {1}\r\nremote-ip: {2}\r\n" +
  "remote-port: {3}\r\ntransport: udp\r\nflags: native\r\n\r\n",
Config.LocalIP, rtpPort + 1, Config.LocalIP, rtpPort);

 WriteLog(LogLevel.Info, command);

 WriteLog(LogLevel.Info, GetServerResponse(sockHandler));


After this, FS writes that unicast has been created on corresponding IPs and
ports. It really creates an UDP socket, but doesn't transmit any data
through it. I tested it with Wireshark and from my application, nothing was
Also, if we specify "transport:tcp" in unicast command, it uses UDP anyway,
that's strange.

Here is how I listen UDP packets.
private void DetectSpeech()
 WriteLog(LogLevel.Info, "Reading audio");
 byte[] FSRecvBuf = new byte[2048];

 IPEndPoint epFS = new IPEndPoint(IPAddress.Loopback,
(RTPSocket.RemoteEndPoint as IPEndPoint).Port);
 FSSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
 FSSocket.ReceiveTimeout = 100000;
 FSSocket.SendTimeout = 100000;
 WriteLog(LogLevel.Info, "Binding socket to " + epFS.Port);

 FSSocket.Connect(new IPEndPoint(IPAddress.Loopback, epFS.Port + 1));

 while (Session.Ready())
  int recvCount = FSSocket.Receive(FSRecvBuf);
  WriteLog(LogLevel.Info, "Received bytes: " + recvCount);

Can someone help me to solve this? Do I do something wrong or I forgot
something or it doesn't work at all?

Best regards.
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