code: private RTPFormat createFormat(int payload, Text description) {
  		MediaType mtype = MediaType.fromDescription(mediaType);
  		switch (mtype) {
  		case AUDIO:
  			return createAudioFormat(payload, description);
  		case VIDEO:
  			return createVideoFormat(payload, description);
  		case APPLICATION:
  			return createApplicationFormat(payload, description);
  		default:
  			return null;
  		}
      }
docs: Creates or updates format using payload number and text format description.
  
  @param payload the payload number of the format.
  @param description text description of the format
  @return format object