code: public void setOutputStream(FLACOutputStream fos) {
      if(fos == null)
        throw new IllegalArgumentException("FLACOutputStream fos must not be null.");
      if(flacWriter == null)
        flacWriter = new FLACStreamController(fos,streamConfig);
      else
        flacWriter.setFLACOutputStream(fos);
    }
docs: Set the output stream to use. This must not be called while an encode
  process is active, or a flac stream is already opened.
  @param fos output stream to use. This must not be null.