Method of motion information coding

A method for motion information encoding, the method comprising:

• obtaining current motion information for encoding a current block;
• determining motion information associated with one or more neighboring blocks of the current block;
• deriving a Merge candidate set that includes one or more Merge candidates based on the motion information associated with the one or more neighboring blocks;
• selecting a target Merge candidate from the Merge candidate set;
• encoding a Merge index corresponding to the target Merge candidate to be signaled via a bitstream;
• and
• generating coded motion information to be signaled via the bitstream, wherein
• the coded motion information indicates predicting a first part of the current motion information based on at least a portion of motion information associated with the target Merge candidate and at least one motion vector difference,
• the coded motion information specifies the at least one motion vector difference that includes an x-component and a y-component, and
• the coded motion information is arranged according to a syntax structure that, when the at least one motion vector difference exists, includes a case where the x-component or the y-component of the at least one motion vector difference is non-zero and excludes a case where the x-component and the y-component of the at least one motion vector difference are both zero.

An apparatus, comprising:

• one or more processors configured to execute a program code to:
• receive a bitstream including coded data for a current block and one or more neighboring blocks of the current block;
• determine motion information associated with the one or more neighboring blocks of the current block;
• derive a Merge candidate set that includes one or more Merge candidates based on the motion information associated with the one or more neighboring blocks;
• determine a target Merge candidate from the Merge candidate set based on a Merge index included in coded motion information that is signaled in the bitstream;
• and
• decode current motion information for decoding the current block, including determining a first part of the current motion information for the current block based on at least a portion of motion information associated with the target Merge candidate and at least one motion vector difference,
• wherein
• the at least one motion vector difference includes an x-component and a y-component,
• the at least one motion vector difference is encoded and included in the coded motion information, and
• the coded motion information is arranged according to a syntax structure that, when the at least one motion vector difference exists, includes a case where the x-component or the y-component of the at least one motion vector difference is non-zero and excludes a case where the x-component and they-component of the at least one motion vector difference are both zero.