An image coding method includes: writing, into a sequence parameter set, buffer description defining information for defining a plurality of buffer descriptions; writing, into the sequence parameter set, reference list description defining information for defining a plurality of reference list descriptions corresponding to the buffer descriptions; and writing, into a first header of each processing unit which is included in a coded bitstream, buffer description selecting information for specifying a selected buffer description.

Provided is an image decoding method including: obtaining, from a sequence parameter set of a bitstream, information indicating a plurality of first reference image lists for an image sequence including a current image; obtaining, from a group header of the bitstream, an indicator for a current block group including a current block in the current image; obtaining a second reference image list based on a first reference image list indicated by the indicator; and prediction-decoding a lower block of the current block based on a reference image included in the second reference image list.

An image coding method includes: deriving a candidate for a motion vector of a current block from a co-located motion vector; adding the candidate to a list; selecting the motion vector of the current block from the list; and coding the current block, wherein the deriving includes: deriving the candidate by a first derivation scheme in the case of determining that each of a current reference picture and a co-located reference picture is a long-term reference picture; and deriving the candidate by a second derivation scheme in the case of determining that each of the current reference picture and the co-located reference picture is a short-term reference picture.

An image coding method includes: deriving a candidate for a motion vector of a current block from a co-located motion vector; adding the candidate to a list; selecting the motion vector of the current block from the list; and coding the current block, wherein the deriving includes: deriving the candidate by a first derivation scheme in the case of determining that each of a current reference picture and a co-located reference picture is a long-term reference picture; and deriving the candidate by a second derivation scheme in the case of determining that each of the current reference picture and the co-located reference picture is a short-term reference picture.

According to the disclosure of the present document, a recovery point picture order count (POC) for a gradual decoding refresh (GDR) picture is derived on the basis of GDR-related information, and an output for pictures related to the GDR picture is determined on the basis of the recovery point POC. The recovery point DOC can be derived on the basis of a syntax element related to the recovery point POC.

A method of encoding a video sequence into a bitstream is provided. The method includes: receiving a video sequence; and encoding one or more pictures of the video sequence; wherein the encoding includes: signaling a first flag in a slice header to indicate whether an active reference index number is present in a slice header; in response to the first flag indicating that the active reference index number is present, determining a number of entries of reference picture list 0, and signaling an active reference index number of reference picture list 0 in the slice header for P and B slices; and determining a number of entries of reference picture list 1, and signaling an active reference index number of reference picture list 1 in the slice header for B slice.

Disclosed is an encoding/decoding method and apparatus related to adaptive deblocking filtering. There is provided an image decoding method performing adaptive filtering in inter-prediction, the method including: reconstructing, from a bitstream, an image signal including a reference block on which block matching is performed in inter-prediction of a current block to be encoded; obtaining, from the bitstream, a flag indicating whether the reference block exists within a current picture where the current block is positioned; reconstructing the current block by using the reference block; adaptively applying an in-loop filter for the reconstructed current block based on the obtained flag; and storing the current block to which the in-loop filter is or is not applied in a decoded picture buffer (DPB).

Disclosed is an encoding/decoding method and apparatus related to adaptive deblocking filtering. There is provided an image decoding method performing adaptive filtering in inter-prediction, the method including: reconstructing, from a bitstream, an image signal including a reference block on which block matching is performed in inter-prediction of a current block to be encoded; obtaining, from the bitstream, a flag indicating whether the reference block exists within a current picture where the current block is positioned; reconstructing the current block by using the reference block; adaptively applying an in-loop filter for the reconstructed current block based on the obtained flag; and storing the current block to which the in-loop filter is or is not applied in a decoded picture buffer (DPB).

A method of video decoding is provided. In the method, a coded video bitstream of a current picture is received. The current picture is divided into a plurality of rows of coding tree units (CTUs). Coding blocks in a first CTU row of the plurality of rows of CTUs are decoded based on motion vector information stored in a history-based motion vector prediction (HMVP) buffer. The motion vector information stored in the HMVP buffer is updated as the coding blocks in the first CTU row are decoded. The HMVP buffer is updated to include the motion vector information of the coding blocks in a first CTU of the first CTU row after the coding block at an end of the first CTU row is decoded.

A method of video decoding is provided. In the method, a coded video bitstream of a current picture is received. The current picture is divided into a plurality of rows of coding tree units (CTUs). Coding blocks in a first CTU row of the plurality of rows of CTUs are decoded based on motion vector information stored in a history-based motion vector prediction (HMVP) buffer. The motion vector information stored in the HMVP buffer is updated as the coding blocks in the first CTU row are decoded. The HMVP buffer is updated to include the motion vector information of the coding blocks in a first CTU of the first CTU row after the coding block at an end of the first CTU row is decoded.