US-12621467-B2 - Method and apparatus for deriving rice parameter in video/image coding system

US12621467B2US 12621467 B2US12621467 B2US 12621467B2US-12621467-B2

Abstract

A video decoding method performed by a decoding apparatus comprises the steps of: acquiring, from a bitstream, residual information for a current transform block, wherein the residual information includes at least one of information indicating a level value of a target transform coefficient within the current transform block or information indicating a residual level value; based on a neighboring transform coefficient of the target transform coefficient, deriving a rice parameter for at least one of the information indicating the level value of the target transform coefficient or the information indicating the residual level value; based on the rice parameter, deriving a bin string for at least one of the information indicating the level value of the target transform coefficient or the information indicating the residual level value; and based on the bin string, deriving the level value of the target transform coefficient.

Inventors

Jungah CHOI
Jin Heo
Sunmi YOO
Jangwon CHOI
Jaehyun Lim
Seunghwan Kim

Assignees

LG ELECTRONICS INC.

Dates

Publication Date: 20260505
Application Date: 20240607

Claims (13)

1 . A video decoding method performed by a decoding apparatus, the method comprising: obtaining residual information for a current transform block from a bitstream, the residual information including at least one of information representing a level value of a target transform coefficient in the current transform block or information representing a residual level value; deriving a Rice parameter for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on a number of available neighboring transform coefficients for the target transform coefficient, based on whether the current transform block being a transform skip block; deriving a bin string for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on the Rice parameter; and deriving the level value of the target transform coefficient based on the bin string, wherein the deriving the Rice parameter comprises: deriving the number of available neighboring transform coefficients; deriving a sum of level values of the available neighboring transform coefficients; and deriving the Rice parameter based on a difference value between the sum of the level values of the available neighboring transform coefficients and a product between a base level and the number of the available neighboring transform coefficients.
2 . The video decoding method of claim 1 , wherein based on the current transform block being the transform skip block, the Rice parameter is derived based on the number of available neighboring transform coefficients.
3 . The video decoding method of claim 1 , wherein based on the current transform block being not the transform skip block, the Rice parameter is derived based on the number of available neighboring transform coefficients.
4 . The video decoding method of claim 1 , wherein the information representing the level value of the transform coefficient corresponds to a dec_abs_level syntax element, and the information representing the residual level value corresponds to an abs_remainder syntax element.
5 . The video decoding method of claim 1 , wherein based on a neighboring transform coefficient being present within a boundary of the current transform block and being present within an effective area after high-frequency zeroing, the neighboring transform coefficient is determined to be available.
6 . The video decoding method of claim 1 , wherein the sum of the level values of the available neighboring transform coefficients is equal to or larger than 0 and equal to or smaller than 31.
7 . The video decoding method of claim 1 , wherein based on the current transform block being not a transform skip block, the number of the available neighboring transform coefficients has an integer value that is equal to or smaller than 5.
8 . The video decoding method of claim 7 , wherein based on the sum of the level values of the available neighboring transform coefficients being equal to or larger than 0 and equal to or smaller than 6, a value of the Rice parameter is 0, wherein based on the sum of the level values of the available neighboring transform coefficients being equal to or larger than 7 and equal to or smaller than 13, the value of the Rice parameter is 1, wherein based on the sum of the level values of the available neighboring transform coefficients being equal to or larger than 14 and equal to or smaller than 27, the value of the Rice parameter is 2, and wherein based on the sum of the level values of the available neighboring transform coefficients being equal to or larger than 28 and equal to or smaller than 31, the value of the Rice parameter is 3.
9 . The video decoding method of claim 1 , wherein based on the current transform block being a transform skip block, the number of the available neighboring transform coefficients has an integer value that is equal to or smaller than 2.
10 . The video decoding method of claim 9 , wherein based on the sum of the level values of the available neighboring transform coefficients being equal to or larger than 0 and equal to or smaller than 11, a value of the Rice parameter is 0, wherein based on the sum of the level values of the available neighboring transform coefficients being equal to or larger than 12 and equal to or smaller than 24, the value of the Rice parameter is 1, and wherein based on the sum of the level values of the available neighboring transform coefficients being equal to or larger than 25 and equal to or smaller than 31, the value of the Rice parameter is 2.
11 . The video decoding method of claim 9 , wherein the available neighboring transform coefficient is a transform coefficient that is present within a boundary of the current transform block between a transform coefficient adjacent to a left side of the target transform coefficient and a transform coefficient adjacent to a top side of the target transform coefficient.
12 . A video encoding method performed by an encoding apparatus, the method comprising: generating at least one of information representing a level value of a target transform coefficient in a current transform block or information representing a residual level value; deriving a Rice parameter for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on a number of available neighboring transform coefficients for the target transform coefficient, based on whether the current transform block being a transform skip block; deriving a bin string for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on the Rice parameter; and encoding the bin string, wherein the deriving the Rice parameter comprises: deriving the number of available neighboring transform coefficients; deriving a sum of level values of the available neighboring transform coefficients; and deriving the Rice parameter based on a difference value between the sum of the level values of the available neighboring transform coefficients and a product between a base level and the number of the available neighboring transform coefficients.
13 . A method for transmitting a bitstream generated by an image encoding method, the image encoding method comprising: generating at least one of information representing a level value of a target transform coefficient in a current transform block or information representing a residual level value; deriving a Rice parameter for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on a number of available neighboring transform coefficients for the target transform coefficient, based on whether the current transform block being a transform skip block; deriving a bin string for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on the Rice parameter; and encoding the bin string, wherein the deriving the Rice parameter comprises: deriving the number of available neighboring transform coefficients; deriving a sum of level values of the available neighboring transform coefficients; and deriving the Rice parameter based on a difference value between the sum of the level values of the available neighboring transform coefficients and a product between a base level and the number of the available neighboring transform coefficients.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a Continuation of U.S. Ser. No. 17/637,290, filed Feb. 22, 2022; which is a National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2020/011117, filed Aug. 20, 2020; which claims the benefit of U.S. Provisional Application No. 62/911,056, filed Oct. 4, 2019, and U.S. Provisional Application No. 62/890,663, filed Aug. 23, 2019, all of which are incorporated by reference in their entirety herein. BACKGROUND OF THE DISCLOSURE Field of the Disclosure The present technology relates to a method and an apparatus for deriving a rice parameter for encoding a transform coefficient in a video/image coding system. 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. SUMMARY A technical subject of the present document is to provide a method and an apparatus for enhancing a video/image coding efficiency. Another technical subject of the present document is to provide a method and an apparatus for improving a residual coding efficiency. Still another technical subject of the present document is to provide a method and an apparatus for deriving a more accurate rice parameter in residual coding. Yet still another technical subject of the present document is to provide a method and an apparatus for reducing a codeword length after binarization in level coding. According to an embodiment of the present document, a video decoding method performed by a decoding apparatus may include: obtaining residual information for a current transform block from a bitstream, the residual information including at least one of information representing a level value of a target transform coefficient in the current transform block or information representing a residual level value; deriving a rice parameter for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on a neighboring transform coefficient of the target transform coefficient; deriving a bin string for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on the rice parameter; and deriving the level value of the target transform coefficient based on the bin string, wherein the rice parameter is derived based on the number of available neighboring transform coefficients for the target transform coefficient and a level value of the available neighboring transform coefficient for the target transform coefficient. According to another embodiment of the present document, a video encoding method performed by an encoding apparatus may include: generating at least one of information representing a level value of a target transform coefficient in a current transform block or information representing a residual level value; deriving a rice parameter for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on a neighboring transform coefficient of the target transform coefficient; deriving a bin string for at least one of the information representing the level value of the target transform coefficient or the information representing the residual level value based on the rice parameter; and encoding the bin string, wherein the rice parameter is derived based on the number of available neighboring transform coefficients for the target transform coefficient and a level value of the available neighboring transform coefficient for the target transform coefficient. According to still another embodiment of the present document, a computer-readable digital storage medium including information causing a decoding apparatus to perform a video decoding method is provided. The video decoding method may include: obtaining residual information for a current transform block from a bitstream, the residual inform