Digital broadcast receiver and method for processing caption thereof

A method of transmitting a digital broadcast signal comprising:

• multiplexing video data, audio data, and supplementary data into MPEG2 transport stream, the supplementary data including an event information table (EIT) and a program map table (PMT),
• wherein the EIT or the PMT includes a caption service descriptor,
• wherein the caption service descriptor includes caption information indicating whether a digital television closed caption service is present in the video data or a line 21 closed caption service is present in the video data in accordance with electronic industry association (ETA) 708;
• wherein the caption service descriptor includes a descriptor length field
• wherein the caption service descriptor further includes language information defining a language associated with the closed caption service,
• wherein the caption service descriptor further includes information indicating the closed caption service is formatted for displays with 16:9 aspect ratio, and
• wherein the caption service descriptor includes a caption service number that is defined only when the digital television closed caption service in accordance with electronic industry association (EIA) 708 is present;
• and
• transmitting the digital broadcast signal.