Method of performing motion vector prediction, and apparatus thereof
A method of performing motion vector prediction for a current block in a picture is provided which includes: deriving a candidate for a motion vector predictor to code a current motion vector of the current block, from a first motion vector of a first block that is spatially adjacent or temporally adjacent to the current block; adding the derived candidate to a list of candidates; and deriving at least one motion vector predictor based on a selected candidate from the list of candidates, wherein the deriving of the candidate includes determining whether to derive the candidate from the first motion vector, based on a type of a current reference picture and a type of a first reference picture, the current reference picture being referred to from the current block using the current motion vector, the first reference picture being referred to from the first block using the first motion vector.
1. A motion vector prediction method of performing motion vector prediction for a current block in a picture, the motion vector prediction method comprising:
deriving a candidate for a motion vector predictor to encode or decode a current motion vector of the current block, from a first motion vector of a first block which is (i) a neighboring block that is included in a current picture including the current block and is adjacent to the current block or (ii) a co-located block included in a picture different from the current picture;
adding the derived candidate to a candidate list; and
deriving at least one motion vector predictor based on a candidate selected from the candidate list,
wherein the deriving of the candidate includes determining whether to derive the candidate from the first motion vector, based on a type of a current reference picture and a type of a first reference picture, the current reference picture being referred to from the current block using the current motion vector, and the first reference picture being referred to from the first block using the first motion vector,
each of the type of the current reference picture and the type of the first reference picture is one of a long term reference picture and a short term reference picture, and
in the determining, (i) the candidate is determined to be derived from the first motion vector when the type of the current reference picture and the type of the first reference picture are the same, and (ii) the candidate is derived, from the candidate list which includes one or more candidates, by using a motion vector other than the first motion vector when the type of the current reference picture and the type of the first reference picture are different.
2. The motion vector prediction method according to claim 1 ,
wherein the deriving of the candidate includes scaling the first motion vector to produce the candidate for the motion vector predictor.
3. A motion vector prediction apparatus for performing motion vector prediction for a current block in a picture, the motion vector prediction apparatus comprising:
a processor; and
a non-transitory computer-readable medium having stored thereon executable instructions that, when executed by the processor, cause the motion vector prediction apparatus to perform the steps of:
deriving a candidate for a motion vector predictor to encode or decode a current motion vector of the current block, from a first motion vector of a first block which is (i) a neighboring block that is included in a current picture including the current block and is adjacent to the current block or (ii) a co-located block included in a picture different from the current picture;
adding the derived candidate to a candidate list; and
deriving at least one motion vector predictor based on a candidate selected from the candidate list,
wherein the deriving of the candidate includes determining whether the candidate is to be derived from the first motion vector, based on a type of a current reference picture and a type of a first reference picture, the current reference picture being referred to from the current block using the current motion vector, and the first reference picture being referred to from the first block using the first motion vector,
each of the type of the current reference picture and the type of the first reference picture is one of a long term reference picture and a short term reference picture, and
in the determining, (i) the candidate is determined to be derived from the first motion vector, when the type of the current reference picture and the type of the first reference picture are the same, and (ii) the candidate is derived, from the candidate list which includes one or more candidates, by using a motion vector other than the first motion vector when the type of the current reference picture and the type of the first reference picture are different.
4. A motion vector prediction apparatus of performing motion vector prediction for a current block in a picture, the motion vector prediction apparatus comprising:
processing circuitry; and
storage accessible from the processing circuitry,
wherein the processing circuitry executes the steps of:
reading, from the storage, a first motion vector of a first block which is (i) a neighboring block that is included in a current picture including the current block and is adjacent to the current block or (ii) a co-located block included in a picture different from the current picture;
deriving, from the first motion vector, a candidate for a motion vector predictor to encode or decode a current motion vector of the current block;
adding the derived candidate to a candidate list; and
deriving at least one motion vector predictor based on a candidate selected from the candidate list,
the deriving of the candidate includes determining whether to derive the candidate from the first motion vector, based on a type of a current reference picture and a type of a first reference picture, the current reference picture being referred to from the current block using the current motion vector, and the first reference picture being referred to from the first block using the first motion vector,
each of the type of the current reference picture and the type of the first reference picture is one of a long term reference picture and a short term reference picture, and
in the determining, (i) the candidate is determined to be derived from the first motion vector when the type of the current reference picture and the type of the first reference picture are the same, and (ii) the candidate is derived, from the candidate list which includes one or more candidates, by using a motion vector other than the first motion vector when the type of the current reference picture and the type of the first reference picture are different.
5. A computer program product, embodied in a non-transitory computer-readable storage medium, comprising instructions executable by a computing processor to perform the motion vector prediction method according to claim 1 .