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

Claim 14:
15. A non-transitory computer-readable storage medium having stored thereon a compressed bitstream, wherein the compressed bitstream is configured for decoding by operations comprising:
determining that motion prediction using optical flow is available for a current frame;
decoding, from the 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, performing operations comprising:
decoding, from the compressed bitstream, a motion vector for the current block;
identifying 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, generating the optical flow reference block using a forward reference frame and a backward reference frame without generating the optical flow reference frame by:
identifying 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
generating 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

decoding the current block based on the optical flow reference block.