Derivation of temporal motion vector prediction candidates in video coding

A device for coding video data, the device comprising:

• a memory configured to store at least a portion of a coded video bitstream;
• and
• one or more processors that are implemented in circuitry and configured to:
• code, via the coded video bitstream, a syntax element that explicitly specifies whether the coded video bitstream includes a plurality of syntax elements that specify parameters of a temporal motion vector prediction (TMVP) candidate derivation process, wherein the syntax element is a binary flag, wherein:
• a first value of the binary flag syntax element, that explicitly specifies whether the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, indicates that the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, and
• a second value of the binary flag syntax element, that explicitly specifies whether the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, indicates that the coded video bitstream does not include the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, and wherein the plurality of syntax elements that specify the parameters of the TMVP candidate derivation process comprise:
• a syntax element that specifies a reference picture list for derivation of a collocated picture for derivation of the TMVP candidate;
• a syntax element that specifies a reference index of the collocated picture;
• and
• a syntax element that specifies a reference picture list for derivation of a motion vector candidate for derivation of the TMVP candidate;
• where the binary flag syntax element has the first value explicitly specifying that the coded video bitstream includes the plurality of syntax elements:
• code the plurality of syntax elements via the coded video bitstream;
• and
• derive, based on parameters specified by the plurality of syntax elements, a TMVP candidate for a current block of a current picture of video data;
• generate, for the current block, a list of motion vector candidates, the list including the derived TMVP candidate;
• and
• predict, based on the list of motion vector candidates, the current block.

A non-transitory computer-readable storage medium storing instructions that, when executed by one or more processors of a video coder, cause the one or more processors to:

• code, via a coded video bitstream, a syntax element that explicitly specifies whether the coded video bitstream includes a plurality of syntax elements that specify parameters of a temporal motion vector prediction (TMVP) candidate derivation process, wherein the syntax element is a binary flag, wherein:
• a first value of the binary flag syntax element, that explicitly specifies whether the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, indicates that the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, and a second value of the binary flag syntax element, that explicitly specifies whether the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, indicates that the coded video bitstream does not include the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, and wherein the plurality of syntax elements that specify the parameters of the TMVP candidate derivation process comprise:
• a syntax element that specifies a reference picture list for derivation of a collocated picture for derivation of the TMVP candidate;
• a syntax element that specifies a reference index of the collocated picture;
• and
• a syntax element that specifies a reference picture list for derivation of a motion vector candidate for derivation of the TMVP candidate;
• where the binary flag syntax element has the first value explicitly specifying specifics that the coded video bitstream includes the plurality of syntax elements:
• code, by the video coder, the plurality of syntax elements via the coded video bitstream;
• and
• derive, by the video coder and based on parameters specified by the plurality of syntax elements, a TMVP candidate for a current block of a current picture of video data;
• generate, for the current block, a list of motion vector candidates, the list including the derived TMVP candidate;
• and
• predict, based on the list of motion vector candidates, the current block.

A device for coding video data, the device comprising:

• means for coding, via a coded video bitstream, a syntax element that explicitly specifies whether the coded video bitstream includes a plurality of syntax elements that specify parameters of a temporal motion vector prediction (TMVP) candidate derivation process, wherein the syntax element is a binary flag, wherein:
• a first value of two possible values of the binary flag syntax element, that explicitly specifies whether the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, indicates that the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, and
• a second value of the two possible values of the binary flag syntax element, that explicitly specifies whether the coded video bitstream includes the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, indicates that the coded video bitstream does not include the plurality of syntax elements that specify parameters of the TMVP candidate derivation process, and wherein the plurality of syntax elements that specify the parameters of the TMVP candidate derivation process comprise:
• a syntax element that specifies a reference picture list for derivation of a collocated picture for derivation of the TMVP candidate;
• a syntax element that specifies a reference index of the collocated picture;
• and
• a syntax element that specifies a reference picture list for derivation of a motion vector candidate for derivation of the TMVP candidate;
• means for coding the plurality of syntax elements via the coded video bitstream where the syntax element explicitly specifies that the coded video bitstream includes the plurality of syntax elements;
• means for deriving, based on parameters specified by the plurality of syntax elements, a TMVP candidate for a current block of a current picture of video data;
• means for generating, for the current block, a list of motion vector candidates, the list including the derived TMVP candidate;
• and
• means for predicting, based on the list of motion vector candidates, the current block.