Multi-Line Intra Prediction Using Selective Smoothing and PDPC
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in intra prediction modes, particularly in handling reference lines and position-dependent intra prediction combinations (PDPC), leading to suboptimal decoding performance.
Innovation Solution
Implementing a method and apparatus that control intra prediction by applying intra smoothing and PDPC on specific reference lines while preventing their application on others, based on a reference line index, to enhance decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intra smoothing and PDPC are applied on all reference lines, then prediction accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies intra smoothing and PDPC selectively based on the reference line index rather than uniformly across all reference lines. Specifically, when the reference line index indicates a first reference line nearest to the coding unit, intra smoothing is applied; when it indicates a second reference line, PDPC is applied. This localized application approach maintains prediction accuracy where needed while reducing unnecessary computations on other reference lines, thereby resolving the contradiction between prediction accuracy and computational complexity.
2Measurement precision
If multiple reference lines are processed with both intra smoothing and PDPC, then decoding precision is improved, but processing time increases
Solution Approach 1:
The patent implements partial action by applying intra smoothing and PDPC only to specific reference lines identified by the reference line index, rather than processing all reference lines with both techniques. This selective application ensures sufficient decoding precision for the most relevant reference lines while avoiding redundant processing on less critical lines, thus reducing overall processing time without significantly compromising decoding precision.
3Productivity
If reference line index is used to control application of intra smoothing and PDPC, then decoding efficiency is improved, but algorithm complexity increases
Solution Approach 1:
The patent uses the reference line index as a pre-established control mechanism to determine which reference lines require intra smoothing and which require PDPC. This preliminary classification, based on the index value, streamlines the decoding process by pre-determining the appropriate processing path for each reference line, thereby improving decoding efficiency. The added algorithmic step of checking the reference line index is offset by the elimination of unnecessary processing, resulting in net efficiency gains.
Data Source
AI summary
A method of and an apparatus for controlling intra prediction for decoding of a video sequence are provided. The method may include based on a reference line index signaling a first reference line nearest to a coding unit, among a plurality of reference lines adjacent to the coding unit, applying intra smoothing on one or more first reference lines comprising the first reference line, among the plurality of reference lines, and based on the intra smoothing being applied on the one or more first reference lines, applying a position-dependent intra prediction combination (PDPC) on one or more third reference lines comprising the first reference line, among the plurality of reference lines, while preventing application of the PDPC on one or more fourth reference lines other than the one or more third reference lines, among the plurality of reference lines.