Transform Coefficient Entropy Coding for Dependent Quantization

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Solution Overview

Problem

Existing video coding technologies face challenges in achieving efficient coding efficiency when using dependent quantization, as the dependency in quantization affects the interrelationship between data items and influences context adaptive entropy coding, leading to suboptimal bitrate and distortion trade-offs.

Innovation Solution

Implement context-adaptive entropy coding and dependent scalar quantization by decoding and encoding transform coefficients using significance, parity, and greatness flags, along with equiprobability entropy decoding/encoding, to adaptively determine reconstruction levels based on preceding coefficients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If dependent quantization is used to reduce bitrate, then the quantization distortion increases due to the dependency influencing the interrelationship between data items

Engineering Contradiction:

ImprovebitrateVSAvoidquantization distortion

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent segments the transform coefficients into multiple groups based on their positions in the scan order and divides the coding process into multiple passes. Each pass processes a specific subset of coefficients, allowing the entropy coder to adapt to the dependency structure introduced by dependent quantization. This segmentation enables optimized coding of each group while maintaining the overall rate-distortion efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic context modeling where the probability contexts for entropy coding are updated and adapted based on the actual quantization dependencies observed in the data. The context adaptive binary arithmetic coding (CABAC) dynamically adjusts its probability models to reflect the interrelationships between coefficients introduced by dependent quantization, optimizing the bitrate for the given distortion level.

Inventive Principle:

Principle #15Dynamics

2Productivity

If context adaptive entropy coding is used to improve coding efficiency, then the complexity of the decoding process increases

Engineering Contradiction:

Improvecoding efficiencyVSAvoiddecoding process complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent performs preliminary analysis of the transform coefficient patterns and pre-establishes multiple context models for different scanning positions and coefficient types. This preliminary preparation allows the actual decoding process to simply select and apply the appropriate pre-configured contexts, significantly reducing the real-time computational complexity while maintaining high coding efficiency through context adaptation.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250324058A1Entropy coding of transform coefficients suitable for dependent scalar quantization

Publication Date: 2025.10.16 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

Concepts for transform coefficient block coding are described which enable coding of coefficients of a transform block in a manner suitable for dependent quantization and effectively implementable by entropy coding in terms of coding efficiency.