Wide-Angle Intra Mode Mapping for Non-Square Block Coding
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Solution Overview
Problem
Existing video coding technologies do not effectively utilize wide angle intra prediction modes for non-square blocks, leading to inefficient bit usage for less likely prediction directions.
Innovation Solution
The method determines whether an angular intra prediction mode for a non-square block is a wide angle mode, and if so, maps it to a corresponding non-wide angle mode within a predetermined threshold, using the specified coding tool for decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wide angle intra prediction modes are used for non-square blocks, then prediction accuracy for less likely directions is improved, but bit usage efficiency deteriorates due to lack of mapping to coding tools
Solution Approach 1:
The patent introduces an intermediary mapping mechanism that translates wide angle intra prediction modes into corresponding non-wide angle modes. This mediator enables the system to leverage existing coding tools while still benefiting from the improved prediction accuracy of wide angle modes for less likely directions.
Solution Approach 2:
The patent changes the parameter space by establishing a correspondence between wide angle modes and non-wide angle modes. This parameter transformation allows the system to use established coding tools with modified parameters, resolving the contradiction between using advanced prediction modes and maintaining bit efficiency.
2Device complexity
If existing coding tools are used without wide angle mode mapping, then device complexity is reduced, but compression ratio deteriorates due to redundancy in bit usage
Solution Approach 1:
The patent makes existing coding tools universal by enabling them to handle both wide angle and non-wide angle prediction modes through the mapping mechanism. This multi-functionality allows the system to maintain simplicity while achieving improved compression ratios through efficient bit usage.
Solution Approach 2:
The mapping mechanism acts as an intermediary layer that bridges existing coding tools and wide angle prediction modes. This mediator enables the system to achieve higher compression ratios without significantly increasing device complexity, as the mapping can be implemented through lookup tables or simple algorithms.
3Loss of information
If wide angle modes are mapped to non-wide modes, then bit usage efficiency is improved, but prediction direction accuracy may be compromised for extreme angles
Solution Approach 1:
The patent applies local quality by differentiating the handling of different prediction modes. The mapping is selectively applied based on the specific mode characteristics, allowing the system to optimize bit usage for certain directions while maintaining accuracy for others through localized mode selection and mapping strategies.
Data Source
AI summary
A method for video decoding includes determining that an angular intra prediction mode for a current block is a wide angle mode. The method further includes determining a non-wide angle mode that corresponds to the wide angle mode, the non-wide angle mode being spaced apart from the vertical mode or the horizontal mode by an angular distance that is less than or equal to the predetermined threshold. The method further includes, in response to a determination that an intra prediction coding tool and coding tool parameters are specified for the determined non-wide angle mode, performing intra prediction for the current block using the wide angle mode, using the intra prediction coding tool, and using the coding tool parameters specified for the determined non-wide angle mode.