docs: private String createTransmitter() {
  
          // Cheated.  Should have checked the type.
          PushBufferDataSource pbds = (PushBufferDataSource) dataOutput;
          PushBufferStream[] pbss = pbds.getStreams();
  
          rtpMgrs = new RTPManager[pbss.length];
          SessionAddress localAddr, destAddr;
          InetAddress ipAddr;
          SendStream sendStream;
          audioReceiver = new AudioReceiver(this, jingleMediaSession);
          int port;
  
          for (int i = 0; i < pbss.length; i++) {
              try {
                  rtpMgrs[i] = RTPManager.newInstance();
  
                  port = portBase + 2 * i;
                  ipAddr = InetAddress.getByName(remoteIpAddress);
  
                  localAddr = new SessionAddress(InetAddress.getByName(this.localIpAddress),
                          localPort);
  
                  destAddr = new SessionAddress(ipAddr, port);
  
                  rtpMgrs[i].addReceiveStreamListener(audioReceiver);
                  rtpMgrs[i].addSessionListener(audioReceiver);
  
                  BufferControl bc = (BufferControl) rtpMgrs[i].getControl("javax.media.control.BufferControl");
                  if (bc != null) {
                      int bl = 160;
                      bc.setBufferLength(bl);
                  }
  
                  try {
  
                      rtpMgrs[i].initialize(localAddr);
  
                  }
                  catch (InvalidSessionAddressException e) {
                      // In case the local address is not allowed to read, we user another local address
                      SessionAddress sessAddr = new SessionAddress();
                      localAddr = new SessionAddress(sessAddr.getDataAddress(),
                              localPort);
                      rtpMgrs[i].initialize(localAddr);
                  }
  
                  rtpMgrs[i].addTarget(destAddr);
  
                  LOGGER.severe("Created RTP session at " + localPort + " to: " + remoteIpAddress + " " + port);
  
                  sendStream = rtpMgrs[i].createSendStream(dataOutput, i);
  
                  sendStreams.add(sendStream);
  
                  sendStream.start();
  
              }
              catch (Exception e) {
                  LOGGER.log(Level.WARNING, "exception", e);
                  return e.getMessage();
              }
          }
  
          return null;
      }