Video decoder and methods

A method for constructing and updating a history-based motion vector predictor (HMVP) list, the method comprising:

• constructing the HMVP list, which is an ordered list of N history-based candidates Hk, k=0, . . . , N−1, associated with motion information of N preceding blocks of a frame preceding the current block, wherein N is greater than or equal to 1, wherein each history-based candidate comprises motion information including at least one of elements:
• i) one or more motion vectors, MVs,
• ii) one or more reference picture indices corresponding to the MVs, or
• iii) one or more bi-prediction weight indices;
• comparing at least one of the elements of each history-based candidate of the HMVP list with a corresponding element of the current block;
• and
• adding the motion information of the current block to the HMVP list, if as a result of the comparing at least one of the elements of each of the history-based candidate of the HMVP list differs from the corresponding element of the current block.

An apparatus for determining motion information for a current block, comprising:

• a memory and a processor coupled to the memory;
• and
• the processor is configured to execute operations comprising:
• constructing the HMVP list, which is an ordered list of N history-based candidates −Hk, k=0, . . . , N−1, associated with motion information of N preceding blocks of a frame preceding the current block, wherein N is greater than or equal to 1, wherein each history-based candidate comprises motion information including at least one of elements:
• i) one or more motion vectors, MVs,
• ii) one or more reference picture indices corresponding to the MVs, and/or
• iii) one or more bi-prediction weight indices;
• adding one or more history-based candidates from the HMVP list into a motion information candidate list for the current block;
• and
• deriving the motion information for the current block based on the motion information candidate list.

An apparatus for determining motion information for a current block of a frame based on a history-based motion vector predictor (HMVP) list, comprising:

• a HMVP list constructing unit configured to construct the HMVP list, which is an ordered list of N history-based candidates—Hk, k=0, . . . , N−1, associated with motion information of N preceding blocks of the frame preceding the current block, wherein N is greater than or equal to 1, wherein each history-based candidate comprises motion information including at least one of elements:
• i) one or more motion vectors, MVs,
• ii) one or more reference picture indices corresponding to the MVs, or
• iii) one or more bi-prediction weight indices;
• a HMVP adding unit configured to add one or more history-based candidates from the HMVP list into a motion information candidate list for the current block;
• and
• a motion information deriving unit configured to derive the motion information for the current block based on the motion information candidate list.

An apparatus for constructing and updating a history-based motion vector predictor (HMVP) list, comprising:

• a HMVP list constructing unit configured to construct the HMVP list, which is an ordered list of N history-based candidates Hk, k=0, . . . -, N−1, associated with motion information of N preceding blocks of a frame preceding the current block, wherein N is greater than or equal to 1, wherein each history-based candidate comprises motion information including at least one of elements:
• i) one or more motion vectors, MVs,
• ii) one or more reference picture indices corresponding to the MVs, or
• iii) one or more bi-prediction weight indices;
• a motion information comparing unit configured to compare at least one of the elements of each history-based candidate of the HMVP list with a corresponding element of the current block;
• and
• a motion information adding unit configured to add the motion information of the current block to the HMVP list, if as a result of the comparing at least one of the elements of each of the history-based candidate of the HMVP list differs from the corresponding element of the current block.

A non-transitory computer-readable storage medium storing video data comprising:

• motion information for a current block of a frame, based on a history-based motion vector predictor (HMVP) list, generated through:
• constructing the HMVP list, which is an ordered list of N history-based candidates—Hk, k=0, . . . , N−1, associated with motion information of N preceding blocks of the frame preceding the current block, wherein N is greater than or equal to 1, wherein each history-based candidate comprises motion information including at least one of elements:
• i) one or more motion vectors, MVs,
• ii) one or more reference picture indices corresponding to the MVs, and/or
• iii) one or more bi-prediction weight indices;
• adding one or more history-based candidates from the HMVP list into a motion information candidate list for the current block;
• and
• deriving the motion information for the current block based on the motion information candidate list.