A digital broadcast system and a method of processing data disclose. A receiving system of the digital broadcast system may include a baseband processor, a management processor, and a presentation processor. The baseband processor receives broadcast signals including mobile service data and main service data. The mobile service data configures a RS frame, and the RS frame includes the mobile service data and at least one type of channel setting information on the mobile service data. The management processor decodes the RS frame to acquire the mobile service data and the at least one type of channel setting information on the mobile service data, then extracts position information of an SDP message. Herein, the SDP message includes Codec information for each component in the respective virtual channel from the channel setting information, thereby accessing the SDP message from the extracted position information and gathers SDP message information. The presentation processor decodes mobile service data of a corresponding component based upon the gathered SDP message information.