Residual Block Repositioning for Entropy Coding Efficiency
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Solution Overview
Problem
Existing video coding techniques face inefficiencies in entropy coding when transform is skipped for residual blocks, as residual data with higher energy is not positioned at the top left corner, affecting compression efficiency.
Innovation Solution
The techniques involve determining whether to reposition residual data of residual blocks by rotating or flipping them based on prediction modes and block sizes, ensuring higher energy data is positioned at the top left corner for improved entropy coding efficiency in both lossy and lossless coding modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transform is skipped for residual blocks in lossy or lossless coding mode, then coding speed and simplicity are improved, but entropy coding efficiency deteriorates because residual data with higher energy is not positioned at the top left corner
Solution Approach 1:
The patent applies preliminary action by repositioning (rotating or flipping) the residual block before entropy coding when transform is skipped. This preprocessing step ensures that residual data with higher energy is positioned at the top left corner of the residual block, optimizing the distribution for subsequent entropy coding operations and improving coding efficiency without requiring transform processing.
2Device complexity
If transform is skipped for residual blocks, then device complexity is reduced, but compression performance deteriorates due to suboptimal residual data distribution
Solution Approach 1:
The patent applies parameter changes by modifying the spatial orientation parameters of the residual block through rotation or flipping operations. By changing the orientation of residual data within the block, the patent optimizes the energy distribution pattern to match the expectations of entropy coding algorithms, thereby improving compression performance without introducing complex transform processing.
3Loss of information
If residual data is repositioned by rotating or flipping, then entropy coding efficiency is improved, but additional processing steps are required
Solution Approach 1:
The patent applies dynamics by making the residual block repositioning operation conditional and adaptive. The rotation or flipping operation is performed only when transform is skipped and only for specific prediction modes (intra prediction modes other than vertical and horizontal). This dynamic approach allows the system to optimize entropy coding efficiency only when and where needed, avoiding unnecessary processing steps in other scenarios.
Data Source
AI summary
Techniques are described for coding residual data of a prediction residual block in either a lossy or lossless coding mode, in which a transform is skipped or bypassed. The techniques of this disclosure include determining whether to reposition, e.g., rotate or flip, residual data of a residual block prior to coding the residual data of the residual block. For both the lossy and lossless coding modes, a video coding device determines whether to reposition residual data of a residual block based on a prediction mode of the residual block and a size of the residual block. In some examples, the techniques disable repositioning for all residual blocks in the inter-prediction mode and the intra block copying prediction mode, and determine to reposition residual blocks in the intra-prediction mode when the residual blocks have block sizes that are less than or equal to a threshold size.