EP-3979645-B1 - MOTION PREDICTION-BASED IMAGE CODING METHOD AND DEVICE

EP3979645B1EP 3979645 B1EP3979645 B1EP 3979645B1EP-3979645-B1

Inventors

JANG, Hyeongmoon
PARK, Naeri
KIM, SEUNGHWAN

Dates

Publication Date: 20260506
Application Date: 20200619

Claims (3)

A decoding method performed by a decoding apparatus, the decoding method comprising: acquiring information on a prediction mode of a current block from a bitstream; deriving the prediction mode of the current block based on the information on the prediction mode; generating prediction samples of the current block based on the prediction mode; and generating reconstructed samples based on the prediction samples, wherein the bitstream includes a sequence parameter set and a coding unit syntax, wherein the sequence parameter set includes a combined inter-picture merge and intra-picture prediction (CIIP) enabled flag, a merge mode with motion vector differences (MMVD) enabled flag, and a triangle partitioning mode enabled flag, wherein the coding unit syntax includes a coding unit (CU) skip flag indicating whether a skip mode is applied to the current block, and wherein the deriving includes parsing a regular merge flag from the bitstream when a product of a height of the current block and a width of the current block is not equal to 32, and one of conditions among a first condition, a second condition, a third condition, and a fourth condition is satisfied, wherein the first condition is satisfied when a value of the MMVD enabled flag is equal to 1, wherein the second condition is satisfied when a maximum number of subblock merge candidates is larger than 0, the width of the current block is equal to or larger than 8, and the height of the current block is equal to or larger than 8, wherein the third condition is satisfied when a value of the CIIP enabled flag is equal to 1, a value of the CU skip flag is equal to 0, the product of the height of the current block and the width of the current block is equal to or larger than 64, the width of the current block is smaller than 128, and the height of the current block is smaller than 128, and wherein the fourth condition is satisfied when a value of the triangle partitioning mode enabled flag is equal to 1, the product of the height of the current block and the width of the current block is equal to or larger than 64, a maximum number of triangle partitioning merge candidates is equal to or larger than 2, and a slice type of a current slice including the current block is equal to B slice, and wherein the prediction mode of the current block is derived as regular merge mode when a value of the regular merge flag is equal to 1.
An encoding method performed by an encoding apparatus, the encoding method comprising: determining a prediction mode of a current block; generating information on the prediction mode based on the prediction mode; and encoding image information including the information on the prediction mode, wherein the image information includes a sequence parameter set and a coding unit syntax, wherein the sequence parameter includes a combined inter-picture merge and intra-picture prediction (CIIP) enabled flag, a merge mode with motion vector differences (MMVD) enabled flag, and a triangle partitioning mode enabled flag, wherein the coding unit syntax includes a coding unit (CU) skip flag indicating whether a skip mode is applied to the current block, and wherein the image information includes a regular merge flag when a product of a height of the current block and a width of the current block is not equal to 32, and one of conditions among a first condition, a second condition, a third condition, and a fourth condition is satisfied, wherein the first condition is satisfied when a value of the MMVD enabled flag is equal to 1, wherein the second condition is satisfied when a maximum number of subblock merge candidates is larger than 0, the width of the current block is equal to or larger than 8, and the height of the current block is equal to or larger than 8, wherein the third condition is satisfied when a value of the CIIP enabled flag is equal to 1, a value of the CU skip flag is equal to 0, the product of the height of the current block and the width of the current block is equal to or larger than 64, the width of the current block is smaller than 128, and the height of the current block is smaller than 128, and wherein the fourth condition is satisfied when a value of the triangle partitioning mode enabled flag is equal to 1, the product of the height of the current block and the width of the current block is equal to or larger than 64, a maximum number of triangle partitioning merge candidates is equal to or larger than 2, and a slice type of a current slice including the current block is equal to B slice, and wherein a value of the regular merge flag being equal to 1 represents that the prediction mode of the current block is a regular merge mode.
A transmission method of data for an image, the transmission method comprising: obtaining a bitstream by encoding the image using the method of claim 2; and transmitting the data comprising the bitstream.

Description

BACKGROUND OF THE DISCLOSURE Field of the disclosure The present disclosure relates to a method and apparatus for coding an image based on motion prediction. Related Art Recently, the demand for high resolution, high quality image/video such as 4K, 8K or more Ultra High Definition (UHD) image/video is increasing in various fields. As the image/video resolution or quality becomes higher, relatively more amount of information or bits are transmitted than for conventional image/video data. Therefore, if image/video data are transmitted via a medium such as an existing wired/wireless broadband line or stored in a legacy storage medium, costs for transmission and storage are readily increased. Moreover, interests and demand are growing for virtual reality (VR) and artificial reality (AR) contents, and immersive media such as hologram; and broadcasting of images/videos exhibiting image/video characteristics different from those of an actual image/video, such as game images/videos, are also growing. Therefore, a highly efficient image/video compression technique is required to effectively compress and transmit, store, or play high resolution, high quality images/videos showing various characteristics as described above. The document JVET-N1001-v8 with the title "Versatile Video Coding (Draft 5)" was published on 11-06-2019 and discloses the then current status of the VVC standardisation effort by the Joint Video Experts Team (JVET). The document contains a description of proposed syntax structures and respective semantics including a sequence parameter set (SPS) syntax and a coding unit (CU) syntax. Syntax elements associated with various coding tools are described including inter-picture merge and intra-picture prediction (CIIP), merge mode with motion vector difference (MMVD), triangle partitioning mode, a skip mode and a regular merge mode. The signalling of a regular_merge_flag is based on a logical OR condition involving an sps_mmvd_enabled_flag and a block size constraint. Patent application EP3913918A1 by WILDS INST STANDARDS & TECH INC [KR] was published after the filing date of the present application, but claims as earliest priority date 18-01-2019. It discloses various alternative embodiments with modified merge syntax structure compared to JVET-N1001-v8. In particular, alternative conditions for the signalling of regular_merge_flag involving further syntax elements (e.g. sps_ciip_enabled_flag, cu_skip_flag, sps_trianble_enabled_flag) are disclosed. SUMMARY The present disclosure provides a method and apparatus for increasing image coding efficiency. The present disclosure also provides a method and apparatus for efficiently performing inter prediction. The present disclosure also provides a method and apparatus for preventing unnecessary signaling during inter prediction. The protected invention is defined by the combination of features as specified in the appended independent claims. Enabling disclosure of the protected invention is provided in the following with reference to the embodiments based on table 6. Other aspects, embodiments and examples are provided for illustrative purposes only and do not define the scope of protection of the invention. In an aspect, a decoding method performed by a decoding apparatus includes: acquiring information on a prediction mode of a current block from a bitstream; deriving the prediction mode of the current block based on the information on the prediction mode; generating prediction samples of the current block based on the prediction mode; and generating reconstructed samples based on the prediction samples, wherein the bitstream includes a sequence parameter set, the sequence parameter set includes a combined inter-picture merge and intra-picture prediction (CIIP) enabled flag, and the deriving includes parsing a regular merge flag from the bitstream based on that a condition based on the CIIP enabled flag and a condition based on a size of the current block are satisfied. In another aspect, an encoding method performed by an encoding apparatus includes: determining a prediction mode of a current block; generating information on the prediction mode based on the prediction mode; and encoding image information including the information on the prediction mode, wherein the image information includes a sequence parameter set, the sequence parameter includes a combined inter-picture merge and intra-picture prediction (CIIP) enabled flag, and the image information includes a regular merge flag based on that a condition based on the CIIP enabled flag and a condition based on a size of the current block are satisfied. In another aspect, a computer-readable digital storage medium includes information causing a decoding apparatus to perform a decoding method, wherein the decoding method includes: acquiring information on a prediction mode of a current block from a bitstream; deriving the prediction mode of the current block based on the information on the prediction mode