A method is provided for transmitting a broadcast signal in a transmitting system. Audio data of a broadcast service is generated. An audio frame coded by an Audio Compression-4 (AC-4) scheme is generated. The audio frame includes configuration information on the audio frame and at least one substream including the audio data and metadata for the audio data. The configuration information includes substream index information and substream size information. Real time Object delivery over Unidirectional Transport (ROUTE) packets containing the audio frame are generated. The ROUTE packets are processed to generate Internet Protocol (IP) packets. The IP packets are processed to generate link layer packets, and the broadcast signal including at least one data pipe that includes the link layer packets is transmitted.