Patent ID: 11949857
Assignee: CANON KABUSHIKI KAISHA
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 4:
5. An apparatus for decoding coding blocks of a coding tree unit for an image frame, from a bitstream, the apparatus comprising:
one or more computer-readable storage media; and
one or more processors that are in communication with the one or more computer-readable storage media and that cooperate with the one or more computer-readable storage media to cause the apparatus to:
determine a chroma format of the image frame, the chroma format having chroma channels of the image frame being subsampled relative to a luma channel of the image frame, wherein the determined chroma format is 4:2:0;
recursively split the coding tree unit into one or more coding units each of which has a luma coding block and chroma coding blocks, using a single tree;
determine whether further split for a chroma coding block is allowed,
wherein, if a block size of a luma coding block of a current coding unit is 8×8 and a block size of chroma coding blocks of the current coding unit is 4×4, a quad split for the chroma coding blocks of the current coding unit is not allowed even if a quad split for the luma coding block of the current coding unit is performed, and
the chroma coding blocks, having the block size of 4×4, of the current coding unit are collocated with four luma coding blocks resulted from a quad split for the luma coding block, having the block size of 8×8, of the current coding unit if the luma coding block of the current coding unit is split by a quad split;
determine that the chroma coding blocks of the current coding unit are to be decoded using intra prediction if the block size of the luma coding block of the current coding unit is 8×8, the block size of the chroma coding blocks of the current coding unit is 4×4, and a current split mode for the current coding unit is a quad split; and
decode the chroma coding blocks of the current coding unit using intra prediction if it is determined that the chroma coding blocks of the current coding unit are to be decoded using intra prediction.