An inter prediction method, performed by a decoding apparatus, the method comprising: receiving picture order count (POC) information, wherein the picture order count (POC) information specifies picture order count (POC) differences for reference pictures; deriving picture order count (POC) values for the reference pictures based on the picture order count (POC) differences; constructing a reference picture list based on the picture order count (POC) values of the reference pictures; and performing an inter prediction on a current block based on the reference picture list, to derive a predicted sample of the current block, wherein a picture order count (POC) value of an i-th reference picture is derived based on a picture order count difference derived from the POC information, wherein for the reference pictures previous to the current picture in picture order count (POC) order, the picture order count (POC) difference is a difference between the picture order count (POC) value of the current picture and the picture order count value of the i-th reference picture when i is equal to 0, and the picture order count (POC) difference is a difference between the picture order count (POC) value of the i-th reference picture and the picture order count (POC) value of an (i-1)-th reference picture when i is greater than 0, wherein for the reference pictures subsequent to the current picture in picture order count (POC) order, the picture order count (POC) difference is a difference between the picture order count (POC) value of the current picture and the picture order count value of the i-th reference picture when i is equal to 0, and the picture order count (POC) difference is a difference between the picture order count (POC) value of the i-th reference picture and the picture order count value of the (i-1)-th reference picture when i is greater than 0. receiving picture order count (POC) information, wherein the picture order count (POC) information specifies picture order count (POC) differences for reference pictures; deriving picture order count (POC) values for the reference pictures based on the picture order count (POC) differences; constructing a reference picture list based on the picture order count (POC) values of the reference pictures; and performing an inter prediction on a current block based on the reference picture list, to derive a predicted sample of the current block, wherein a picture order count (POC) value of an i-th reference picture is derived based on a picture order count difference derived from the POC information, wherein for the reference pictures previous to the current picture in picture order count (POC) order, the picture order count (POC) difference is a difference between the picture order count (POC) value of the current picture and the picture order count value of the i-th reference picture when i is equal to 0, and the picture order count (POC) difference is a difference between the picture order count (POC) value of the i-th reference picture and the picture order count (POC) value of an (i-1)-th reference picture when i is greater than 0, wherein for the reference pictures subsequent to the current picture in picture order count (POC) order, the picture order count (POC) difference is a difference between the picture order count (POC) value of the current picture and the picture order count value of the i-th reference picture when i is equal to 0, and the picture order count (POC) difference is a difference between the picture order count (POC) value of the i-th reference picture and the picture order count value of the (i-1)-th reference picture when i is greater than 0. <EOS>