US-20260129230-A1 - METHOD AND APPARATUS FOR VIDEO CODING USING SUBBLOCK CODING ORDER CHANGE AND INTRA PREDICTION ACCORDING TO SAME

US20260129230A1US 20260129230 A1US20260129230 A1US 20260129230A1US-20260129230-A1

Abstract

A method for decoding a current block includes determining at least one intra prediction mode of the current block; determining a partitioning mode of the current block; partitioning the current block into multiple subblocks based on the partitioning mode; and reconstructing the current block. Reconstructing the current block includes: generating prediction samples of the subblocks on a per subblock basis by performing a prediction process including an intra prediction based on the intra prediction mode of the current block.

Inventors

Joo Hyung Byeon
Dong Gyu Sim
Min Hun Lee
Seung Wook Park
Jin Heo

Assignees

HYUNDAI MOTOR COMPANY
KIA CORPORATION
KWANGWOON UNIVERSITY INDUSTRY-ACADEMIC COLLABORATION FOUNDATION

Dates

Publication Date: 20260507
Application Date: 20251230
Priority Date: 20210908

Claims (12)

1 . A method for decoding a current block, the method comprising: determining at least one intra prediction mode of the current block; determining a partitioning mode of the current block; partitioning the current block into multiple subblocks based on the partitioning mode; and reconstructing the current block, wherein reconstructing the current block comprises: generating prediction samples of the subblocks on a per subblock basis by performing a prediction process including an intra prediction based on the intra prediction mode of the current block.
2 . The method of claim 1 , wherein the partitioning mode is determined based on the intra prediction mode of the current block.
3 . The method of claim 2 , wherein determining the partitioning mode comprises: setting the partitioning mode of the current block as a vertical partitioning mode in which the current block is vertically partitioned into the subblocks, when the intra prediction mode of the current block is included in a set of near-horizontal modes.
4 . The method of claim 2 , wherein determining the partitioning mode comprises: setting the partitioning mode of the current block as a horizontal partitioning mode in which the current block is horizontally partitioned into the subblocks, when the intra prediction mode of the current block is included in a set of near-vertical modes.
5 . The method of claim 1 , wherein reconstructing the current block comprises: determining a coding order of the subblocks, wherein the coding order is selected from either a first coding order or a second coding order, which is reverse of the first coding order; determining, for a current subblock to be currently reconstructed among the subblocks, an intra-prediction mode of the current subblock based on the intra-prediction mode of the current block; predicting the current subblock based on the intra prediction mode of the current subblock to generate prediction samples for the current subblock; and reconstructing the current subblock based on the prediction samples for the current subblock, wherein reconstructed samples of the current subblock are used as a reference sample for intra prediction of subblocks that follow the current subblock in the coding order.
6 . The method of claim 5 , wherein determining the coding order of the subblocks comprises: decoding, from a bitstream, a coding order flag for use in the determining the coding order.
7 . The method of claim 6 , wherein, for the subblocks partitioned in the horizontal direction, determining the coding order of the subblocks comprises: when the coding order flag is false, setting the coding order to the first coding order starting from a top subblock and ending at a bottom subblock; and when the coding order flag is true, setting the coding order to the second coding order starting from the bottom subblock and ending at the top subblock.
8 . The method of claim 6 , wherein, for the subblocks partitioned in the vertical direction, determining the coding order of the subblocks comprises: when the coding order flag is false, setting the coding order of the subblocks to the first coding order starting from a leftmost subblock and ending at a rightmost subblock; and when the coding order flag is true, setting the coding order of the subblocks to the second coding order starting from the rightmost subblock and ending at the leftmost subblock.
9 . The method of claim 6 , wherein, for the subblocks partitioned in a Quadtree (QT) partitioning mode in which the current block is partitioned into four subblocks in both horizontal and vertical directions, determining the coding order of the subblocks comprises: when the coding order flag is false, setting the coding order of the subblocks to the first coding order starting from a top left subblock and ending at a bottom right subblock; and when the coding order flag is true, setting the coding order of the subblocks to the second coding order starting from the bottom right subblock and ending at the top left subblock.
10 . The method of claim 5 , wherein the coding order of the subblocks is implicitly inferred based on the intra prediction mode of the current block.
11 . A method for encoding a current block, the method comprising: determining at least one intra prediction mode of the current block; determining a partitioning mode of the current block; partitioning the current block into multiple subblocks based on the partitioning mode; and reconstructing the current block, wherein reconstructing the current block comprises: generating prediction samples of the subblocks on a per subblock basis by performing a prediction process including an intra prediction based on the intra prediction mode of the current block.
12 . A method for providing a video decoding apparatus with video data, the method comprising: encoding the video data into a bitstream; and transmitting the bitstream to the video decoding apparatus, wherein encoding the video data comprises: determining at least one intra prediction mode of a current block; determining a partitioning mode of the current block; partitioning the current block into multiple subblocks based on the partitioning mode; and reconstructing the current block, wherein reconstructing the current block comprises: generating prediction samples of the subblocks on a per subblock basis by performing a prediction process including an intra prediction based on the intra prediction mode of the current block.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation application of non-provisional U.S. patent application Ser. No. 18/586,024, filed on Feb. 23, 2024, which is a continuation of International Application No. PCT/KR2022/012238, filed on Aug. 17, 2022, which claims priority to and the benefit of Korean Patent Application No. 10-2021-0119525, filed on Sep. 8, 2021, and Korean Patent Application No. 10-2022-0101869, filed on Aug. 16, 2022, the entire disclosures of each of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a video coding method and an apparatus using subblock coding order change and resultant intra prediction. BACKGROUND The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. Since video data has a large amount of data compared to audio or still image data, the video data requires a lot of hardware resources, including a memory, to store or transmit the video data without processing for compression. Accordingly, an encoder is generally used to compress and store or transmit video data. A decoder receives the compressed video data, decompresses the received compressed video data, and plays the decompressed video data. Video compression techniques include H.264/AVC, High Efficiency Video Coding (HEVC), and Versatile Video Coding (VVC), which has improved coding efficiency by about 30% or more compared to HEVC. However, since the image size, resolution, and frame rate gradually increase, the amount of data to be encoded also increases. Accordingly, a new compression technique providing higher coding efficiency and an improved image enhancement effect than existing compression techniques is required. The Intra Sub-Partitions (ISP) technique is to perform intra prediction on the current block by further dividing the current block into subblocks for the intra-prediction processing. ISP performs the partitioning into subblocks by using a flag that determines whether to perform the partition in ISP mode and by using a flag that determines whether to perform the partition horizontally or vertically. At this time, the current block is partitioned into subblocks by implicitly determining 2 or 4 subblocks based on the size of the current block. Sequentially from top to bottom in the case of horizontal partitioning mode and from left to right in the case of vertical partitioning mode, the partitioned subblocks are reconstructed by using intra prediction, entropy reconstruction, inverse quantization, and inverse transform. On the second and subsequent subblocks, intra prediction may be performed using reconstruction samples of the previously reconstructed subblock. Based on the intra-prediction mode, the order of reconstruction of the subblocks may be changed. Therefore, to improve the coding efficiency and improve video quality, there is a need to further improve the intra-prediction method of the subblocks according to the reconstruction order. SUMMARY The present disclosure seeks to provide a video coding method and an apparatus for improving video coding efficiency and video quality when performing intra prediction on subblocks of a current block. When a coding order of the subblocks is changed, the video coding method and the apparatus efficiently provide reference samples and perform intra prediction on the subblocks using the reference samples. At least one aspect of the present disclosure provides a method performed by a video decoding apparatus for decoding subblocks partitioned from a current block. The method includes decoding, from a bitstream, an intra-prediction mode of the current block, a partitioning mode of the subblocks, and a coding order flag. Here, the partitioning mode includes a Quadtree (QT) partitioning mode and a Vertical and Horizontal (VH) partitioning mode. The method also includes partitioning the current block into the subblocks according to the partitioning mode. The method also includes determining a coding order of the subblocks based on the coding order flag. The method also includes reconstructing the subblocks sequentially in the coding order by using the intra-prediction mode. Another aspect of the present disclosure provides a method performed by a video encoding apparatus for encoding subblocks partitioned from a current block. The method includes determining an intra-prediction mode of the current block, a partitioning mode of the subblocks, and a coding order flag. Here, the partitioning mode includes a Quadtree (QT) partitioning mode and a Vertical and Horizontal (VH) partitioning mode. The method also includes partitioning the current block into the subblocks according to the partitioning mode. The method also includes determining a coding order of the subblocks based on the coding order flag. The method also includes encoding the subblocks sequentially in the coding order by using the intra-prediction mode.