Block-Based Adaptive Loop Filter Signaling for Video Coding Efficiency

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Solution Overview

Problem

Current video encoding and decoding technologies face inefficiencies in signaling adaptive loop filtering (ALF) parameters, leading to increased signaling overhead and reduced coding efficiency.

Innovation Solution

The proposed techniques involve determining slice-level syntax elements to infer or signal block-level syntax elements for adaptive loop filtering, enabling or disabling ALF on a per-block basis, and encoding this information in the bitstream to reduce overhead and improve coding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If block-level syntax elements are explicitly signaled for each block, then precise control of ALF application is achieved, but signaling overhead increases

Engineering Contradiction:

Improvecontrol precisionVSAvoidsignaling overhead

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent divides the video data into slices, and within each slice, further divides into blocks. Different syntax element signaling strategies are applied at different segmentation levels (slice-level vs block-level), allowing selective inference or explicit signaling based on the specific block's needs, thus reducing overall signaling overhead while maintaining precise control where necessary

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different quality levels of syntax element signaling to different blocks within the same slice. Some blocks use inferred syntax elements (lower quality/control) while others use explicitly signaled syntax elements (higher quality/control), optimizing the balance between signaling overhead and control precision for each local region

Inventive Principle:

Principle #3Local quality

2Loss of information

If slice-level syntax elements are used to infer block-level syntax elements, then signaling overhead is reduced, but coding efficiency decreases

Engineering Contradiction:

Improvesignaling overheadVSAvoidcoding efficiency

Core Design Contradiction:

Loss of informationVSProductivity

Solution Approach 1:

The patent introduces a dynamic syntax element that can switch between two states: inferred (defaulting to a first value) and explicitly signaled. This dynamic approach allows the coding system to adapt to different content characteristics, using inference for homogeneous regions (reducing overhead) and explicit signaling for heterogeneous regions (maintaining efficiency)

Inventive Principle:

Principle #15Dynamics

3Reliability

If adaptive loop filter is enabled for all blocks, then video quality is improved, but computational complexity increases

Engineering Contradiction:

Improvevideo qualityVSAvoidcomputational complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of applying ALF to all blocks unconditionally, the patent uses syntax elements to selectively enable ALF only for blocks where it provides significant quality improvement. This partial action approach reduces computational complexity while maintaining video quality in critical regions

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11140418B2Block-based adaptive loop filter design and signaling

Publication Date: 2021.10.05 QUALCOMM INC

AI summary

A video decoder can be configured to set each block-level syntax element of a plurality of block-level syntax elements to a value indicating that an adaptive loop filter is enabled for an associated component of the video data in response to determining that a slice-level syntax element is set to a value indicating that values for the plurality of block-level syntax elements are inferred.