Adaptive CABAC Probability Updates for Non-Coded Syntax

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Solution Overview

Problem

The MPEG-4 AVC Standard's probability estimation process for video coding is limited, leading to slow convergence and instability, particularly in SKIP/Direct modes where certain syntax elements are not coded, resulting in potential damage to future coding processes.

Innovation Solution

Implementing an adaptive probability update process for non-coded syntax elements, allowing for probability estimation updates even when syntax elements are not encoded, which enhances the accuracy and speed of probability estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If probability estimation is only updated after each symbol is encoded in CABAC, then the coding process is simple and fast, but the probability convergence is slow and the estimation becomes unstable

Engineering Contradiction:
Improveprobability estimation stabilityVSAvoidcoding process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by updating probability estimates for non-coded syntax elements before they are actually coded. This allows the probability model to adapt in advance to expected symbol patterns, improving convergence speed and stability without waiting for actual symbol occurrences during the coding process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by making the probability update mechanism adaptive and flexible. The system dynamically adjusts probability estimates based on context information and coding patterns, allowing the model to evolve during the coding process rather than following a rigid update schedule.

Inventive Principle:
Principle #15Dynamics

2Productivity

If SKIP/Direct mode is used to infer syntax from decoded information without coding, then coding efficiency is improved, but probability estimation accuracy deteriorates due to lack of updates

Engineering Contradiction:
Improvecoding efficiencyVSAvoidprobability estimation accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by performing probability updates for non-coded syntax elements in SKIP/Direct modes before actual coding occurs. This ensures that even when syntax elements are not explicitly coded, their probability estimates are still updated based on inferred values, maintaining accuracy while preserving coding efficiency.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using the inferred syntax values from SKIP/Direct modes to update probability estimates. This creates a feedback loop where the decoded information is fed back into the probability model, allowing continuous adaptation even when explicit coding is skipped.

Inventive Principle:
Principle #23Feedback

3Device complexity

If the probability adaptation is restricted to slice duration in MPEG-4 AVC, then the coding structure is simple, but the adaptation range is limited and convergence is slow

Engineering Contradiction:
Improvecoding structure simplicityVSAvoidprobability convergence speed
Core Design Contradiction:
Device complexityVSSpeed

Solution Approach 1:

The patent implements dynamics by allowing probability adaptation to extend beyond slice boundaries. The adaptive probability update mechanism dynamically adjusts probabilities across a wider range, enabling faster convergence while maintaining a relatively simple coding structure through contextual inheritance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies universality by creating a probability update mechanism that serves multiple purposes: it works within slices, across slices, and for both coded and non-coded syntax elements. This multi-functional approach accelerates convergence without requiring separate mechanisms for different scenarios.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2449781A1Methods and apparatus for adaptive probability update for non-coded syntax
Publication Date: 2012.05.09 THOMSON LICENSING SA

AI summary

There is provided an apparatus. The apparatus includes an encoder (100) for encoding picture data for at least a block. The encoder (100) applies a probability update process to at least one of a non-coded symbol and a non-coded syntax associated with the block.