Unequal weight planar motion vector derivation
A system and method of planar motion vector derivation which, in some embodiments can employ an unequal weighted combination of adjacent motion vectors. In some embodiments, motion vector information associated with a bottom right pixel or block adjacent to a current coding unit can be derived from motion information associated with a top row or top neighboring row of a current coding unit and motion information associated with a left column or left neighboring column of a current coding unit. Weighted or non-weighted combinations of such values can be combined in a planar mode prediction model to derive associated motion information for bottom and/or right adjacent pixels or blocks.
1. A method of decoding a video included in a bitstream by a decoder, comprising:
(a) receiving said bitstream indicating how a coding tree unit was partitioned into coding units according to a quad tree plus multi tree structure that allows a square parent node to be split with a quaternary tree partitioning that splits said square parent node in half in both horizontal and vertical directions to define leaf nodes that are square in shape each of which are the same size, wherein said quad tree plus multi tree structure allows one of said leaf nodes to be split based upon one selected from a group consisting of,
(i) a symmetric binary tree partitioning that splits one of said leaf nodes of said quaternary tree partitioning in half in either a horizontal direction or a vertical direction resulting in two blocks that are the same size as leaf nodes, and
(ii) an asymmetric tree partitioning that splits one of said leaf nodes of said quaternary tree partitioning in either a horizontal direction or a vertical direction resulting in three blocks two of which are different in size than a third one of said three blocks as leaf nodes;
(b) identifying final coding units to be decoded represented by leaf nodes of the quad tree plus multi tree structure;
(c) receiving both (1) a first motion vector associated with a coding unit of a B-slice of a current frame of said video, where one of said final coding units is said coding unit included in a bi-predictive slice of said current frame of said video, referencing a temporally previous reference slice of a temporally previous reference frame relative to said current frame of said coding unit, and a (2) a second motion vector associated with said coding unit of said B-slice of said current frame of said video referencing a temporally future reference slice of a temporally future frame relative to said current frame of said coding unit;
(d) wherein said coding unit of said B-slice of said current frame of said video has a top neighboring row, a left neighboring column, a bottom neighboring row and a right neighboring column, each of said top neighboring row, left neighboring column, bottom neighboring row, and right neighboring column in the said current frame;
(e) modifying at least one of said first motion vector and said second motion vector based at least in part upon the other of said at least one of said first motion vector and said second motion vector and based upon an optical flow of said temporally previous reference slice and said temporally future reference slice;
(f) decoding said coding unit based upon said modified at least one of said first motion together with said temporally previous reference slice of said temporally previous frame and said second motion vector together with said temporally future reference slice of said temporally future frame.