Variable Length Coding With One-Way Probability Table Biasing

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Solution Overview

Problem

The existing variable length coding methods for moving picture coding, such as H.263, face inefficiencies due to the inability to adaptively switch probability tables effectively when coefficient values decrease after initially increasing, leading to reduced coding efficiency.

Innovation Solution

A method that scans coefficient values from higher-frequency to lower-frequency components and switches probability tables only in one direction when an absolute value exceeds a threshold, maintaining a biased probability distribution for improved coding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If probability tables are switched based on the absolute value of the previous coefficient value in existing techniques, then coding is performed adaptively, but coding efficiency is reduced when the absolute value of a certain coefficient is smaller than that of the previous coefficient

Engineering Contradiction:

Improveadaptability to coefficient value trendsVSAvoidcoding efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

Instead of switching probability tables in both directions based on coefficient value comparisons, the invention inverts the approach by switching tables in only one direction (when current coefficient exceeds previous coefficient). This prevents unnecessary table switches that occur when coefficients fluctuate, thereby maintaining coding efficiency while still adapting to the general increasing trend of coefficient values from high to low frequency components.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If probability tables are updated based on input binary data frequency, then probability tables adapt to data distribution, but coding efficiency is reduced without biased probability distributions

Engineering Contradiction:

Improveprobability table adaptationVSAvoidcoding efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The invention applies local quality by introducing a bias parameter that differentiates the update behavior of probability tables based on local characteristics of coefficient values. When coefficient values show an increasing trend, the probability tables are updated with a bias toward certain outcomes, creating locally optimized probability distributions that improve coding efficiency for specific patterns of coefficient data.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7742528B2Variable length encoding method and variable length decoding method

Publication Date: 2010.06.22 GODO KAISHA IP BRIDGE 1

AI summary

A variable length coding method is comprised of: a coefficient value scanning step in which an RL sequence generation unit 203, a reordering unit 202, and a binarization unit 203 scan coefficient values within a block in a predetermined scanning order starting at a higher-frequency component toward a lower-frequency component; and an arithmetic coding step in which an arithmetic coding unit 205 and a table storage unit 204 perform arithmetic coding on the absolute values of the coefficient values according to the scanning order used in the coefficient value scanning step, by switching between probability tables 1˜4 for use, wherein, in the arithmetic coding step, a probability table to be used is switched to another probability table in one direction, when the arithmetic-coded absolute values of the coefficient values include an absolute value exceeding a predetermined threshold value.