Deriving bi-prediction with coding unit-level weight indices for merge candidates

Patent metadata

Field	Value
Publication number	US-12489886-B2
Application number	US-202318215753-A
Country	US
Kind code	B2
Filing date	Jun 28, 2023
Priority date	Jul 4, 2022
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

A VVC-standard encoder and a VVC-standard decoder are provided, implementing derivation of a BCW index according to cost values based on template matching. A template matching cost can be calculated for each among a set of possible BCW weight values, and a BCW weight value yielding a lowest template matching cost among each template matching cost calculated can be selected as a BCW index for a bi-predicted merge candidate. Alternatively, a template matching cost can be calculated for each among a subset of possible BCW weight values based on an inherited BCW weight. Additionally, a merge candidate BCW index can be derived while adjusting template matching cost of an inherited BCW weight from a value calculated according to the VVC standard and ECM specifications, or while adjusting template matching cost of a BCW weight having equal weight from a value calculated according to the VVC standard and ECM specifications.

First claim

What is claimed is:

1 . A computing system, comprising:
one or more processors, and a computer-readable storage medium communicatively coupled to the one or more processors, the computer-readable storage medium storing computer-readable instructions executable by the one or more processors that, when executed by the one or more processors, perform associated operations comprising:
calculating, for each BCW weight value among a subset of possible BCW weight values which is similar to an inherited BCW weight, a respective absolute difference between the respective BCW weight value and the inherited BCW weight; and
calculating a template matching cost of each BCW weight value for which a respective absolute difference is smaller than a pre-defined threshold; and
deriving, for a bi-predicted merge candidate of a merge candidate list of a merge-coded coding unit (CU), a bi-prediction with CU-level weight (BCW) index of the bi-predicted merge candidate by selecting a BCW weight value yielding a lowest template matching cost among each template matching cost calculated as the BCW index of the bi-predicted merge candidate.

2 . The computing system of claim 1 , wherein a template matching cost comprises a sum of absolute differences between samples of a template of the merge-coded CU and respective corresponding reference samples.

3 . The computing system of claim 1 , wherein deriving a BCW index of the bi-predicted merge candidate according to a template matching cost comprises:
calculating a template matching cost for each BCW weight value among a set of possible BCW weight values, and selecting a BCW weight value yielding a lowest template matching cost among each template matching cost calculated as the BCW index of the bi-predicted merge candidate.

4 . The computing system of claim 3 , wherein the associated operations further comprise:
calculating a weighted averaging bi-prediction according to an equation comprising P bi-pred =((16−w)*P 0 +w*P 1 +8)>>4.

5 . The computing system of claim 4 , wherein the set of possible BCW weight values comprises {6, 7, 8, 9, 10}.

6 . The computing system of claim 1 , wherein deriving a BCW index of the bi-predicted merge candidate according to a template matching cost comprises:
calculating a template matching cost for each BCW weight value among a subset of possible BCW weight values based on an inherited BCW weight, and; selecting a BCW weight value yielding a lowest template matching cost among each template matching cost calculated as the BCW index of the bi-predicted merge candidate.

7 . The computing system of claim 6 , wherein the template matching cost is calculated for each BCW weight value among a subset of possible BCW weight values based on the inherited BCW weight being a negative weight with respect to a weighted averaging bi-prediction equation.

8 . The computing system of claim 7 , wherein the weighted averaging bi-prediction equation comprises P bi-pred =((8−w)*P 0 +w*P 1 +4)>>3.

9 . The computing system of claim 1 , wherein deriving a BCW index of the bi-predicted merge candidate according to a template matching cost comprises:
calculating a template matching cost for each BCW weight value among a subset of possible BCW weight values based on an inherited BCW weight, the subset being further based on respective picture order count (POC) distances between a current picture and a plurality of reference pictures, and; selecting a BCW weight value yielding a lowest template matching cost among each template matching cost calculated as the BCW index of the bi-predicted merge candidate.

10 . The computing system of claim 9 , wherein the respective POC distances comprise a first POC distance between the current picture and a reference picture of a first reference picture list, and a second POC distance between the current picture and a reference picture of a second reference picture list.

11 . The computing system of claim 10 , wherein calculating a template matching cost for each BCW weight value among a subset of possible BCW weight values comprises:
calculating a template matching cost of each BCW weight value smaller than or equal to an equal weight with respect to a weighted averaging bi-prediction equation, in the event that the first POC distance is smaller than the second POC distance; and calculating a template matching cost of each BCW weight value equal to or larger than the equal weight, in the event that the first POC distance is larger than the second POC distance.

12 . The computing system of claim 11 , wherein the weighted averaging bi-prediction equation comprises P bi-pred =(8−w)*P 0 +w*P 1 +4)>>3.

13 . The computing system of claim 1 , wherein the associated operations further comprise:
adjusting a template matching cost of an inherited BCW weight to be preferentially selected over template matching costs of other BCW weights.

14 . The computing system of claim 13 , wherein adjusting the template matching cost of the inherited BCW weight comprises multiplying the template matching cost of the inherited BCW weight by a weight smaller than 1.

15 . The computing system of claim 13 , wherein adjusting the template matching cost of the inherited BCW weight comprises applying a bitwise shift operation and a subtraction operation to scale the template matching cost of the inherited BCW weight by a factor smaller than 1.

16 . The computing system of claim 1 , wherein the associated operations further comprise:
adjusting a template matching cost of a BCW weight comprising an equal weight with respect to a weighted averaging bi-prediction equation to be preferentially selected over template matching costs of other BCW weights.

17 . The computing system of claim 16 , wherein adjusting the template matching cost of the BCW weight comprising an equal weight comprises multiplying the template matching cost of the BCW weight comprising an equal weight by a weight smaller than 1.

Assignees

• Alibaba China Co Ltd

Inventors

• Liao Ru-Ling
• Chen Jie
• Ye Yan
• Li Xinwei

Classifications

• H04N19/159 Primary

  Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction · CPC title

• H04N19/172

  the region being a picture, frame or field · CPC title

• H04N19/52

  by predictive encoding · CPC title

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/577

  Motion compensation with bidirectional frame interpolation, i.e. using B-pictures · CPC title