Position-Dependent Intra Prediction Combination for Efficient Video Coding
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Solution Overview
Problem
Existing video coding systems face challenges in efficiently addressing blocking artifacts at higher QP values due to discontinuities in intra prediction, particularly in VVC and HEVC, which require complex post-processing like PDPC to smooth out these artifacts, leading to increased computational complexity.
Innovation Solution
A simplified post-processing method for position-dependent intra prediction combination (PDPC) that modifies sample values based on a weighted average of left or top reference samples, reducing computational complexity without compromising compression performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex post-processing like PDPC is used to smooth out blocking artifacts, then compression performance is improved, but computational complexity increases
Solution Approach 1:
The patent changes the parameters of the PDPC algorithm by using simplified weight calculation formulas and selective application based on prediction mode and block position. Instead of applying complex PDPC to all blocks, it applies simplified versions only where needed (e.g., at block boundaries with specific prediction modes), reducing computational complexity while maintaining compression performance.
Solution Approach 2:
The patent segments the application of PDPC by dividing the image into different regions (e.g., blocks at boundaries vs. interior blocks) and applying different levels of processing. By segmenting the processing based on block position and prediction mode, the patent reduces unnecessary computations in regions where PDPC is less critical while maintaining artifact reduction where needed.
2Reliability
If PDPC is applied to all blocks, then compression efficiency is improved, but processing time increases
Solution Approach 1:
The patent applies partial PDPC processing rather than full PDPC to all blocks. By applying the simplified PDPC only to specific blocks (e.g., those with discontinuities or at boundaries) and using simplified weight calculations, the patent achieves sufficient compression efficiency without the excessive processing time that would result from applying full PDPC universally.
Solution Approach 2:
The patent applies different levels of PDPC processing to different regions of the image based on local characteristics such as block position, prediction mode, and presence of discontinuities. This local quality approach ensures that computationally intensive processing is applied only where necessary to maintain compression efficiency, rather than uniformly across the entire image.
Data Source
AI summary
Described are video coding systems comprising a post-processing stage using position dependent intra prediction combination where a predicted sample is modified based on a weighting between a value of a left or top reference sample and the obtained predicted value for the sample, wherein the left or top reference sample is determined based on the intra prediction angle. This provides better computing efficiency while keeping identical compression performance. Encoding method, decoding method, encoding apparatus and decoding apparatus based on this post-processing stage are proposed.