# US 2021/0344934 A1 · Method and Apparatus of Subblock Deblocking in Video Coding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0344934 A1 - Document ID: US20210344934A1 - Status: Published application - Kind: A1 - Application number: 17/270,610 - Filed: 2019-08-30 - Published: 2021-11-04 - Earliest claimed: 2018-08-31 - Assignees: Mediatek Inc. - Applicants: Mediatek Inc. - Inventors: Chia-Ming TSAI; Chih-Wei HSU; Ching-Yeh CHEN; Tzu-Der CHUANG; Yu-Wen HUANG - Web page: https://patentgrep.com/patent/US20210344934A1 ## CPC - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/86: involving reduction of coding artifacts, e.g. of blockiness - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/167: Position within a video image, e.g. region of interest [ROI] - H04N 19/184: the unit being bits, e.g. of the compressed video stream - H04N 19/513: Processing of motion vectors - H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Method and apparatus for constrained de-blocking filter are disclosed. According to one method, if a CU is partitioned into multiple sub-CUs, the de-blocking process is also applied to the sub-block boundaries inside the current filtered-reconstructed block. According to another method, if first reference samples used for the de-blocking process of a first boundary are to be modified by the de-blocking process of a second boundary, the first reference samples are replaced by padding samples that are not to be modified by the de-blocking process of the second boundary. According to yet another method, the de-blocking process is applied to a reconstructed block corresponding to a current block to result in a current filtered-reconstructed block regardless whether a boundary of the current block corresponds to an 8×8 sample grid boundaries. ## Claims ### Claim 1 A method of de-blocking of reconstructed picture in for video encoding or video decoding, the method comprising: receiving input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side; determining a block boundary of the current block and sub-block boundaries inside the current block, wherein the current block is partitioned into a plurality of sub-blocks using sub-block mode prediction; applying de-blocking process to a reconstructed current block corresponding to the current block to result in a current filtered-reconstructed block, wherein said applying the de-blocking process to the current block comprises applying the de-blocking process to the sub-block boundaries inside the current filtered-reconstructed block; and generating a filtered decoded picture including the current filtered-reconstructed block. ### Claim 2 (depends on 1) The method of claim 1, wherein the sub-block mode prediction is one mode in a group comprising Advanced Temporal Motion Vector Prediction (ATMVP) mode, affine mode or Planar Motion Vector Prediction (MVP) mode. ### Claim 3 (depends on 1) The method of claim 1, wherein a target sub-block has a first boundary corresponding to the block boundary of the current block and a second boundary inside the current block; a target width or height of the target sub-block is designated as K, at most M samples on the first boundary are allowed to be filtered by the de-blocking process and at most N samples on the second boundary are allowed to be filtered by the de-blocking process; (M+N) is constrained to be smaller than or equal to K; and wherein K, M and N are positive integers, and the first boundary and the second boundary correspond to two vertical boundaries or two horizontal boundaries of the target sub-block. ### Claim 4 (depends on 3) The method of claim 3, wherein K is equal to 8, M is smaller than or equal to 3, and N is smaller than or equal to 3. ### Claim 5 (depends on 3) The method of claim 3, wherein K is equal to 8, M is smaller than or equal to 5, and N is smaller than or equal to 2. ### Claim 6 (depends on 1) The method of claim 1, wherein a target sub-block has a first boundary corresponding to the block boundary of the current block and a second boundary inside the current block; a block size of the target sub-block corresponds to K×K; and at most K/2 samples on the first boundary are filtered by the de-blocking process. ### Claim 7 An apparatus of Inter prediction for video coding, the apparatus comprising one or more electronic circuits or processors arranged to: receive input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side; determine a block boundary of the current block and sub-block boundaries inside the current block, wherein the current block is partitioned into a plurality of sub-blocks using sub-block mode prediction; apply de-blocking process to a reconstructed current block corresponding to the current block to result in a current filtered-reconstructed block, wherein the de-blocking process applied to the current block comprises applying the de-blocking process to the sub-block boundaries inside the current filtered-reconstructed block; and generate a filtered decoded picture including the current filtered-reconstructed block. ### Claim 8 A method of de-blocking of reconstructed picture in for video encoding or video decoding, the method comprising: receiving input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side; determining a first boundary and a second boundary associated with the current block, wherein the first boundary and the second boundary correspond to two vertical boundaries or two horizontal boundaries of the current block; applying de-blocking process to a reconstructed current block corresponding to the current block to result in a filtered-reconstructed current block, wherein if one or more first reference samples used for the de-blocking process of the first boundary are to be modified by the de-blocking process of the second boundary, said one or more first reference samples are replaced by one or more padding samples that are not to be modified by the de-blocking process of the second boundary; and generating a filtered decoded picture including the filtered-reconstructed current block. ### Claim 9 (depends on 8) The method of claim 8, wherein the current block corresponds to a coding unit (CU) or the current block corresponds to one of a plurality of sub-CUs partitioned from the coding unit using sub-block mode prediction. ### Claim 10 (depends on 9) The method of claim 9, wherein the sub-block mode prediction is one mode in a group comprising Advanced Temporal Motion Vector Prediction (ATMVP) mode, affine mode or Planar Motion Vector Prediction (MVP) mode. ### Claim 11 (depends on 8) The method of claim 8, wherein for each pixel line perpendicular to the first boundary and the second boundary, said one or more first reference samples to be modified by the de-blocking process of the second boundary are replaced by a target second reference pixel used for the de-blocking process of the second boundary, and wherein the target second reference pixel is closest to said one or more first reference samples in said each pixel line perpendicular to the first boundary. ### Claim 12 An apparatus of Inter prediction for video coding, the apparatus comprising one or more electronic circuits or processors arranged to: receive input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side; determine a first boundary and a second boundary associated with the current block, wherein the first boundary and the second boundary correspond to two vertical boundaries or two horizontal boundaries of the current block; apply de-blocking process to a reconstructed current block corresponding to the current block to result in a filtered-reconstructed current block, wherein if one or more first reference samples used for the de-blocking process of the first boundary are to be modified by the de-blocking process of the second boundary, said one or more first reference samples are replaced by one or more padding samples that are not to be modified by the de-blocking process of the second boundary; and generate a filtered decoded picture including the filtered-reconstructed current block. ### Claim 13 A method of de-blocking of reconstructed picture in for video encoding or video decoding, the method comprising: receiving input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side; applying de-blocking process to a reconstructed current block corresponding to the current block to result in a current filtered-reconstructed block regardless whether a boundary of the current block corresponds to 8×8 sample grid boundaries; and generating a filtered decoded picture including the current filtered-reconstructed block. ### Claim 14 (depends on 13) The method of claim 13, wherein when a side length of each side of the boundary of the current block is 4, at most one sample on each side of the boundary of the current block are modified by the de-blocking process. ### Claim 15 An apparatus of Inter prediction for video coding, the apparatus comprising one or more electronic circuits or processors arranged to: receive input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side; apply de-blocking process to a reconstructed current block corresponding to the current block to result in a current filtered-reconstructed block regardless whether a boundary of the current block corresponds to 8×8 sample grid boundaries; and generate a filtered decoded picture including the current filtered-reconstructed block.