Reducing motion vector information transmission in bi-directional temporal prediction

A method of decoding a video included in a bitstream comprising:

• (a) receiving a rectangular coding unit of a coding tree unit of luma samples included in a bi-predictive B-slice of a current frame of said video;
• (b) receiving a first motion vector associated with said coding unit of said bi-predictive B-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;
• (c) receiving a second motion vector associated with said coding unit of said bi-predictive B-slice of said current frame of said video referencing a temporally future reference slice of a temporally future reference frame relative to said current frame of said coding unit;
• (d) applying an optical flow between said temporally previous reference slice and said temporally future reference slice to perform a sample based motion modification after motion compensation based upon at least one of said first motion vector and said second motion vector;
• and
• (e) decoding said coding unit based upon said sample based motion modification as a result of said applying said optical flow between said temporally previous reference slice and said temporally future reference slice.

A bitstream of compressed video for decoding by a decoder, including a non-transitory computer readable storage medium storing the compressed video, the method comprising:

• (a) said bitstream containing data indicating a rectangular coding unit of a coding tree unit of luma samples included in a bi-predictive B-slice of a current frame of said video;
• (b) said bitstream containing data indicating a first motion vector associated with said coding unit of said bi-predictive B-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;
• (c) said bitstream containing data indicating a second motion vector associated with said coding unit of said bi-predictive B-slice of said current frame of said video referencing a temporally future reference slice of a temporally future reference frame relative to said current frame of said coding unit;
• (d) said bitstream containing data indicating an optical flow between said temporally previous reference slice and said temporally future reference slice to perform a sample based motion modification after motion compensation based upon at least one of said first motion vector and said second motion vector;
• and
• (e) said bitstream containing data indicating said coding unit based upon said sample based motion modification as a result of said applying said optical flow between said temporally previous reference slice and said temporally future reference slice.

A method of encoding a video included in a bitstream by an encoder comprising:

• (a) providing an encoded bitstream including a rectangular coding unit of a coding tree unit of luma samples included in a bi-predictive B-slice of a current frame of said video;
• (b) providing an encoded bitstream including a first motion vector associated with said coding unit of said bi-predictive B-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;
• (c) providing an encoded bitstream including a second motion vector associated with said coding unit of said bi-predictive B-slice of said current frame of said video referencing a temporally future reference slice of a temporally future reference frame relative to said current frame of said coding unit;
• (d) providing an encoded bitstream including an optical flow between said temporally previous reference slice and said temporally future reference slice to perform a sample based motion modification after motion compensation based upon at least one of said first motion vector and said second motion vector;
• and
• (e) providing an encoded bitstream including said coding unit based upon said sample based motion modification as a result of said applying said optical flow between said temporally previous reference slice and said temporally future reference slice.