Patent ID: 11876974
Assignee: GOOGLE LLC
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 5:
6. A device, comprising:
a processor configured to:
determine that motion prediction using optical flow is available for a current frame;
decode, from a compressed bitstream, a flag indicating whether a current block of the current frame is encoded using optical flow; and
responsive to determining that the flag indicates that the current block is encoded using optical flow, the processor is configured to:
decode, from the compressed bitstream, a motion vector for the current block;
identify a location of an optical flow reference block within an optical flow reference frame based on the motion vector;
subsequent to identifying the location of the optical flow reference block, generate the optical flow reference block using a forward reference frame and a backward reference frame, wherein to generate the optical flow reference block comprises to:
identify an extended optical flow reference block by extending the optical flow reference block at each boundary of the optical flow reference block by an amount related to a filter length of a filter used in sub-pixel interpolation; and
generate pixel values of only the extended optical flow reference block by performing an optical flow estimation using the forward reference frame and the backward reference frame without generating the optical flow reference frame in its entirety; and

decode the current block based on the optical flow reference block and the motion vector.