docs: public synchronized String start() {
          if (started) return null;
  
          // Create a processor for the specified jmf locator
          String result = createProcessor();
          if (result != null) {
              started = false;
          }
  
          // Create an RTP session to transmit the output of the
          // processor to the specified IP address and port no.
          result = createTransmitter();
          if (result != null) {
              processor.close();
              processor = null;
              started = false;
          }
          else {
              started = true;
          }
  
          // Start the transmission
          processor.start();
  
          return null;
      }