EP-4736124-A1 - IMPLICIT MASKED BLENDING MODE IMPROVEMENT WITH HIGH LEVEL SYNTAX

Abstract

A computing system receives a video bitstream comprising a current picture that includes a first block. The system determines that the first block is encoded using a first reference block and a second reference block. The system identifies a high-level syntax (HLS) flag in the video bitstream that indicates a weighting scheme for using the first and second reference blocks. The system reconstructs the first block using a first set of weighting factors for reference values from the first reference and second reference blocks when the HLS flag has a first value. The system reconstructs the first block using a second set of weighting factors for the reference values from the first and second reference blocks when (i) the HLS flag has a second value and (ii) at least one of the first and second reference blocks is at least partially outside of a corresponding reference boundary.

Inventors

• GAO, Han
• ZHAO, XIN
• ZHAO, LIANG
• YE, JING
• LIU, SHAN

Assignees

• Tencent America LLC

Dates

Publication Date

20260506

Application Date

20230908

Claims (20)

1. What is claimed is: 1. A method of video decoding performed at a computing system having memory and one or more processors, the method comprising: receiving a video bitstream comprising a current picture that includes a first block; determining that the first block is encoded using a first reference block and a second reference block; identifying a high-level syntax (HLS) flag in the video bitstream that indicates whether an implicit masked blending mode is enabled for the first block, wherein the implicit masked blending mode is associated with a weighting scheme for using the first reference block and the second reference block; in accordance with the HLS flag having a first value, reconstructing the first block using a first set of weighting factors for reference values from the first reference block and the second reference block; and in accordance with (i) the HLS flag having a second value and (ii) a determination that at least one of the first reference block and the second reference block is at least partially outside of a corresponding reference boundary, reconstructing the first block using a second set of weighting factors for the reference values from the first reference block and the second reference block.
2. 2. The method of claim 1, wherein the second set of weighting factors correspond to a non-averaged weighting.
3. 3. The method of claim 1, wherein the second set of weighting factors correspond to a masked blending.
4. 4. The method of claim 1, wherein the HLS flag is signaled at a sequence level.
5. 5. The method of claim 1, wherein the HLS flag is signaled at a frame level.
6. 6. The method of claim 1, wherein the HLS flag is signaled in at a tile or subpicture level.
7. 7. The method of claim 1, further comprising: identifying a second HLS flag in the video bitstream that indicates a granularity of position checks for generating a boundary-dependent mask; in accordance with the second HLS flag having a first corresponding value, performing a respective position check at each of a set of sample locations; and in accordance with the second HLS flag having a second corresponding value, forgoing performing the respective position check at a subset of the sample locations.
8. 8. The method of claim 7, wherein the second HLS flag is signaled at a frame, sequence, tile, or subpicture level.
9. 9. The method of claim 1, further comprising: identifying a third HLS flag in the video bitstream that indicates a weighting factor to be used for out-of-boundary positions; in accordance with the third HLS flag having a first corresponding value, applying a first set of weighting factors for out-of-boundary positions; and in accordance with the third HLS flag having a second corresponding value, applying a second set of weighting factors for out-of-boundary positions.
10. 10. The method of claim 9, wherein the third HLS flag is signaled at a frame, sequence, tile, or subpicture level.
11. 11. The method of claim 1, wherein a default value for the HLS flag is 1.
12. 12. The method of claim 1, wherein the corresponding reference boundary is a picture boundary, a slice boundary, a subpicture boundary, or a tile boundary.
13. 13. A computing system, comprising: control circuitry; memory; and one or more sets of instructions stored in the memory and configured for execution by the control circuitry, the one or more sets of instructions comprising instructions for: receiving a video bitstream comprising a current picture that includes a first block; determining that the first block is encoded using a first reference block and a second reference block; identifying a high-level syntax (HLS) flag in the video bitstream that indicates whether an implicit masked blending mode is enabled for the first block, wherein the implicit masked blending mode is associated with a weighting scheme for using the first reference block and the second reference block; in accordance with the HLS flag having a first value, reconstructing the first block using a first set of weighting factors for reference values from the first reference block and the second reference block; and in accordance with (i) the HLS flag having a second value and (ii) a determination that at least one of the first reference block and the second reference block is at least partially outside of a corresponding reference boundary, reconstructing the first block using a second set of weighting factors for the reference values from the first reference block and the second reference block.
14. 14. The computing system of claim 13, wherein the second set of weighting factors correspond to a non-averaged weighting.
15. 15. The computing system of claim 13, wherein the second set of weighting factors correspond to a masked blending.
16. 16. The computing system of claim 13, wherein the HLS flag is signaled at a sequence level.
17. 17. A non-transitory computer-readable storage medium storing one or more sets of instructions configured for execution by a computing device having control circuitry and memory, the one or more sets of instructions comprising instructions for: receiving a video bitstream comprising a current picture that includes a first block; determining that the first block is encoded using a first reference block and a second reference block; identifying a high-level syntax (HLS) flag in the video bitstream that indicates whether an implicit masked blending mode is enabled for the first block, wherein the implicit masked blending mode is associated with a weighting scheme for using the first reference block and the second reference block; in accordance with the HLS flag having a first value, reconstructing the first block using a first set of weighting factors for reference values from the first reference block and the second reference block; and in accordance with (i) the HLS flag having a second value and (ii) a determination that at least one of the first reference block and the second reference block is at least partially outside of a corresponding reference boundary, reconstructing the first block using a second set of weighting factors for the reference values from the first reference block and the second reference block.
18. 18. The non-transitory computer-readable storage medium of claim 17, wherein the second set of weighting factors correspond to a non-averaged weighting.
19. 19. The non-transitory computer-readable storage medium of claim 17, wherein the second set of weighting factors correspond to a masked blending.
20. 20. The non-transitory computer-readable storage medium of claim 17, wherein the HLS flag is signaled at a sequence level.

Description

Implicit Masked Blending Mode Improvement with High Level Syntax RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. 63/523,566, entitled “Implicit Masked Blending Mode Improvement with High Level Syntax,” filed June 27, 2023, and is a continuation of and claims priority to U.S. Patent Application No. 18/241,755, entitled “Implicit Masked Blending Mode Improvement with High Level Syntax” filed on September 01, 2023. TECHNICAL FIELD [0002] The disclosed embodiments relate generally to video coding, including but not limited to systems and methods for linear and non-linear blending of block sections in wedge- based prediction modes. BACKGROUND [0003] Digital video is supported by a variety of electronic devices, such as digital televisions, laptop or desktop computers, tablet computers, digital cameras, digital recording devices, digital media players, video gaming consoles, smart phones, video teleconferencing devices, video streaming devices, etc. The electronic devices transmit and receive or otherwise communicate digital video data across a communication network, and/or store the digital video data on a storage device. Due to a limited bandwidth capacity of the communication network and limited memory resources of the storage device, video coding may be used to compress the video data according to one or more video coding standards before it is communicated or stored. The video coding can be performed by hardware and/or software on an electronic/client device or a server providing a cloud service. [0004] Video coding generally utilizes prediction methods (e.g., inter-prediction, intra-prediction, or the like) that take advantage of redundancy inherent in the video data. Video coding aims to compress video data into a form that uses a lower bit rate, while avoiding or minimizing degradations to video quality. Multiple video codec standards have been developed. For example, High-Efficiency Video Coding (HEVC/H.265) is a video compression standard designed as part of the MPEG-H project. ITU-T and ISO/IEC published the HEVC/H.265 standard in 2013 (version 1), 2014 (version 2), 2015 (version 3), and 2016 (version 4). Versatile Video Coding (VVC/H.266) is a video compression standard intended as a successor to HEVC. ITU-T and ISO/IEC published the VVC/H.266 standard in 2020 (version 1) and 2022 (version 2). AOMedia Video 1 (AV1) is an open video coding format designed as an alternative to HEVC. On January 8, 2019, a validated version 1.0.0 with Errata 1 of the specification was released. SUMMARY [0005] The present disclosure describes using an implicit masked blending mode (e.g., a boundary-aware compound prediction) for blending block sections. For example, in a compound predicted block, reference blocks from the reference pictures can be at least partially out of boundary. In some systems, portions of reference block that are out of boundary are padded and thus do not reflect the real pixel values, which can result in a less accurate prediction. The disclosed methods and systems provide a more accurate reconstruction that is based on real pixel data (e.g., real pixel data is weighted more heavily), thereby improving coding accuracy (e.g., by reducing artifacts in the decoded video data). In addition, a high-level syntax (HLS) flag may be used to indicate a weighting scheme (e.g., averaged or non-averaged weighting) that is used for one or more predictors and a respective corresponding picture boundary (e.g., whether a predictor is fully inside, fully outside, or partially outside a respective corresponding picture boundary). The use of the HLS flag allows for the more complicated non-averaged weighting to be selectively enabled, providing improved accuracy (e.g., more accurate reconstruction based on real pixel data) while enabled and reducing computational cost while disabled (e.g., using a simple average rather than weights). [0006] In accordance with some embodiments, a method of video decoding is provided. The method includes (a) receiving a video bitstream comprising a current picture that includes a first block, where the first block is encoded using a first reference block and a second reference block; (b) identifying a high-level syntax (HLS) flag in the video bitstream that indicates a weighting scheme for using the first reference block and the second reference block; (c) in accordance with the HLS flag having a first value, reconstructing the first block using a first set of weighting factors for reference values from the first reference block and the second reference block; and (d) in accordance with (i) the HLS flag having a second value and (ii) a determination that at least one of the first reference block and the second reference block is at least partially outside of a corresponding reference boundary, reconstructing the first block using a second set of weighting factors for the reference values from the first reference block and the seco