a positive integer. (b2) Set j to one, wherein j is a positive integer. (b3) Set k to one, wherein k is a positive integer. (b4) It is to determine whether the k-th GOP has a frame number greater than i; if not, the method proceeds to step (b7). (b5) It is to determine whether the (i+1)-th type of frame of the k-th GOP has a frame number greater than j; if not, the method proceeds to step (b7). (b