Methods and apparatuses for encoding and decoding video using temporal motion vector prediction
A method of encoding a video into a coded video bitstream with temporal motion vector prediction comprises: determining a value of a flag for indicating whether temporal motion vector prediction is used or not used for the inter-picture prediction of a sub-picture unit of a picture; and writing the flag having the value into a header of the sub-picture unit or a header of the picture; wherein if the flag indicates that temporal motion vector prediction is used, the method further comprises: creating a first list of motion vector predictors comprising a plurality of motion vector predictors including at least one temporal motion vector predictor derived from at least one motion vector from a collocated reference picture; selecting a motion vector predictor out of the first list; and writing a first parameter into the coded video bitstream for indicating the selected motion vector predictor out of the first list.
1. A method of decoding a coded video bitstream with temporal motion vector prediction, the method comprising:
parsing a flag from a header of a sub-picture unit or a header of a picture of the coded video; and
determining whether the flag indicates that temporal motion vector prediction is used or not used;
wherein if the flag indicates that temporal motion vector prediction is used, the method further comprises:
creating a first list of motion vector predictors comprising a plurality of motion vector predictors derived from at least one motion vector from a collocated reference picture; and
parsing a first parameter from the coded video bitstream which indicates a selected motion vector predictor out of the first list for a prediction unit in the sub-picture unit; and
wherein if a temporal layer of the picture is determined to be the lowest or base layer, the flag is set to indicate that temporal motion vector prediction is not used; otherwise, the flag is set to indicate that temporal motion vector prediction is used.
2. An apparatus for decoding a coded video bitstream with temporal motion vector prediction, the apparatus comprising:
a processor; and
a non-transitory memory having stored thereon executable instructions, which when executed by the processor, cause the processor to perform operations including:
parsing a flag from a header of a sub-picture unit or a header of a picture of the coded video; and
determining whether the flag indicates that temporal motion vector prediction is used or not used;
wherein if the flag indicates that temporal motion vector prediction is used, the operations further include:
creating a first list of motion vector predictors comprising a plurality of motion vector predictors derived from at least one motion vector from a collocated reference picture; and
parsing a first parameter from the coded video bitstream which indicates a selected motion vector predictor out of the first list for a prediction unit in the sub-picture unit; and
wherein if a temporal layer of the picture is determined to be the lowest or base layer, the flag is set to indicate that temporal motion vector prediction is not used; otherwise, the flag is set to indicate that temporal motion vector prediction is used.