Inter prediction method and apparatus

A decoding method for a decoding device, the decoding method comprising:

• obtaining a bitstream comprising a plurality of merge indexes;
• constructing a merging candidate list of a current picture block;
• in response to determining that a number of merging candidates in the merging candidate list is less than a maximum number of candidates of the merging candidate list minus N, adding another history-based motion vector predictor (HMVP) candidate in an HMVP candidate set to the merging candidate list continuously after one HMVP candidate in the HMVP candidate set is added to the merging candidate list to obtain a new merging candidate list, wherein N is a positive integer;
• in response to determining that the number of merging candidates in the new merging candidate list is equal to the maximum number of candidates of the merging candidate list minus N, adding a pairwise average merging candidate to the new merging candidate list to obtain a modified merging candidate list;
• obtaining a merge index of the current picture block from the plurality of merge indexes;
• obtaining motion information of the current picture block based on the modified merging candidate list and the merge index;
• and
• determining a predicted block of the current picture block based on the motion information of the current picture block.

An encoding device, comprising:

• one or more processors;
• and
• a computer-readable storage medium coupled to the one or more processors and storing programming instructions, which when executed for execution by the one or more processors, to cause the encoding device to:
• construct a merging candidate list of a current picture block;
• in response to determining that a number of merging candidates in the merging candidate list is less than a maximum number of candidates of the merging candidate list minus N, add another history-based motion vector predictor (HMVP) candidate in an HMVP candidate set to the merging candidate list continuously after one HMVP candidate in the HMVP candidate set is added to the merging candidate list to obtain a new merging candidate list, wherein N is a positive integer;
• in response to determining that the number of merging candidates in the new merging candidate list is equal to the maximum number of candidates of the merging candidate list minus N, add a pairwise average merging candidate to the new merging candidate list to obtain a modified merging candidate list;
• obtain a merge index of the current picture block;
• obtain motion information of the current picture block based on the modified merging candidate list and the merge index;
• determine a predicted block of the current picture block based on the motion information of the current picture block;
• and
• encode the merge index into a bitstream.

A decoding device, comprising:

• one or more processors;
• and
• a computer-readable storage medium coupled to the one or more processors and storing programming instructions, which when executed by the one or more processors, cause the decoding device to:
• obtain a bitstream comprising a plurality of merge indexes;
• construct a merging candidate list of a current picture block;
• in response to determining that a number of merging candidates in the merging candidate list is less than a maximum number of candidates of the merging candidate list minus N, add another history-based motion vector predictor (HMVP) candidate in an HMVP candidate set to the merging candidate list continuously after one HMVP candidate in the HMVP candidate set is added to the merging candidate list to obtain a new merging candidate list, wherein N is a positive integer;
• in response to determining that the number of merging candidates in the new merging candidate list is equal to the maximum number of candidates of the merging candidate list minus N, add a pairwise average merging candidate to the new merging candidate list to obtain a modified merging candidate list;
• obtain a merge index of the current picture block from the plurality of merge indexes;
• obtain motion information of the current picture block based on the modified merging candidate list and the merge index;
• and
• determine a predicted block of the current picture block based on the motion information of the current picture block.

A non-transitory computer-readable medium comprising a bitstream generated by an encoding method, wherein the encoding method comprises:

• constructing a merging candidate list of a current picture block;
• in response to determining that a number of merging candidates in the merging candidate list is less than a maximum number of candidates of the merging candidate list minus N, adding another history-based motion vector predictor (HMVP) candidate in an HMVP candidate set to the merging candidate list continuously after one HMVP candidate in the HMVP candidate set is added to the merging candidate list to obtain a new merging candidate list, wherein N is a positive integer;
• in response to determining that the number of merging candidates in the new merging candidate list is equal to the maximum number of candidates of the merging candidate list minus N, adding a pairwise average merging candidate to the new merging candidate list to obtain a modified merging candidate list;
• obtaining a merge index of the current picture block;
• obtaining motion information of the current picture block based on the modified merging candidate list and the merge index;
• determining a predicted block of the current picture block based on the motion information of the current picture block;
• and
• encoding the merge index into the bitstream.