Transmitter and additional parity generating method thereof

A receiving method of a receiving apparatus operable in a mode among a plurality of modes, the receiving method comprising:

• receiving a television (TV) broadcast signal including a first frame and a second frame from a transmitting apparatus;
• demodulating data of a first codeword included in the first frame to generate first values;
• demodulating data of a second codeword included in the second frame to generate second values;
• inserting predetermined values;
• if the mode is a predetermined mode among the plurality of modes, adding third values among the first values and the inserted values to fourth values among the first values and the inserted values and adding fifth values among the second values to sixth values among the first values and the inserted values;
• and
• decoding the added values and remaining values among the first values and the inserted values based on a low density parity check (LDPC) code to generate output bits corresponding to the TV broadcast signal,
• wherein if a mode of the transmitting apparatus is the predetermined mode, the first codeword is based on remaining parity bits after puncturing one or more parity bits from parity bits generated based on information bits, and repetition parity bits selected from the generated parity bits, and the second codeword is based on one or more parity bits selected among the repetition parity bits and the generated parity bits,
• wherein a number of the selected one or more parity bits is calculated based on a number of the repetition parity bits,
• wherein the third values correspond to the repetition parity bits,
• wherein the fifth values correspond to the selected one or more parity bits,
• wherein the predetermined values correspond to the punctured parity bits, and
• wherein the second frame is received prior to the first frame.