Context-Grouped Arithmetic Coding for Fast Code Amount Prediction
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Solution Overview
Problem
Conventional systems fail to precisely predict the code amount in provisional coding without arithmetic coding, leading to inefficiencies in processing time and accuracy.
Innovation Solution
A coder that divides binary symbol sequences into groups based on context and uses an arithmetic code amount approximating circuit to predict code amounts in parallel, reducing processing time and improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If arithmetic coding is applied in provisional coding, then code amount prediction precision is improved, but processing time increases significantly
Solution Approach 1:
The binary symbol sequence is divided into multiple groups based on different contexts (e.g., different syntax elements, different probability ranges). Each group is processed by a separate code amount approximating circuit in parallel, reducing the overall processing time while maintaining prediction precision through context-specific approximation.
Solution Approach 2:
Instead of performing full arithmetic coding in provisional coding, the patent uses simplified code amount approximating circuits that replicate the essential prediction functionality. These circuits copy the structure and logic of arithmetic coding but use approximate calculations (e.g., using lookup tables, simplified probability models) to achieve fast prediction without the computational overhead of complete arithmetic decoding.
2Loss of time
If conventional provisional coding without arithmetic coding is used, then processing time is reduced, but code amount prediction precision deteriorates
Solution Approach 1:
The code amount approximating circuits perform preliminary code amount prediction during provisional coding using simplified models. This preliminary action provides sufficiently accurate predictions for mode selection and resource allocation decisions, avoiding the need for complete arithmetic coding in the provisional stage while maintaining adequate prediction precision for practical purposes.
Solution Approach 2:
The patent changes the parameters of the coding process by using approximate probability values and simplified calculation methods in the code amount approximating circuits. Instead of using exact arithmetic coding algorithms, it employs parameterized approximation models (e.g., fixed probability tables, simplified range calculations) that trade off some precision for significant speed improvement, which is acceptable for provisional coding purposes.
3Manufacturing precision
If full arithmetic coding is performed, then coding precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential code amount prediction functionality from the complete arithmetic coding process. The code amount approximating circuits implement simplified versions that capture the core prediction logic while removing complex components such as iterative renormalization, exact probability updates, and full arithmetic decoding procedures. This extraction maintains sufficient coding precision for mode selection while dramatically reducing circuit complexity.
Solution Approach 2:
The patent uses disposable, simplified approximation models in the code amount approximating circuits rather than implementing permanent, complex arithmetic coding hardware. These approximation circuits use pre-computed lookup tables, fixed probability models, and simplified calculation logic that are easier and cheaper to implement in hardware, providing adequate precision for provisional coding without the high complexity of full arithmetic coding circuits.
Data Source
AI summary
A coder has a binarizing circuit (130) for converting multivalued data into a binary symbol sequence, the multivalued data being generated from an input signal and having a plurality of contexts, an arithmetic code amount approximating circuit (200) for calculating a prediction code amount in the predetermined coding unit from the binary symbol sequence, and a coding circuit (102) for coding the input signal arithmetically on the basis of the prediction code amount. The arithmetic code amount approximating circuit (200) includes a selector (230) for dividing the binary symbol sequence into a plurality of groups based on the contexts, a plurality of code amount approximating circuits (211-214) for calculating, from the binary symbol sequence divided into a plurality of groups, the prediction code amount of the group based on at least the section range in arithmetic coding, and an adder (231) for adding the prediction code amounts from all code amount approximating circuits and outputting the prediction code amount in the specified coding unit.