Entropy Context Initialization With Reduced-Precision Probability States
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Solution Overview
Problem
Existing video coding technologies face challenges in achieving a balance between coding efficiency and implementation complexity, particularly in context-adaptive binary entropy coding, where the accuracy of slope and offset values for probability estimation initialization can lead to suboptimal results and increased memory demands.
Innovation Solution
The proposed solution involves reducing the accuracy of slope and offset values for initializing probability estimation in context-adaptive binary entropy coding, allowing for a compromise between coding efficiency and complexity by deriving these values from a linear equation with reduced precision, specifically using the first and second four-bit parts of an 8-bit initialization value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high accuracy slope and offset values are used for probability estimation initialization, then coding efficiency is improved, but memory requirements and implementation complexity increase
Solution Approach 1:
The patent changes the precision parameter of slope and offset values from high precision (e.g., 8-bit or higher) to reduced precision (e.g., 4-bit or lower). This parameter change reduces memory storage requirements and simplifies implementation while the patent demonstrates that the reduced precision does not significantly degrade coding performance, thus resolving the contradiction between coding efficiency and device complexity
Solution Approach 2:
The patent employs simplified, lower-precision representations of probability estimation parameters that can be easily stored and processed. These reduced-precision slope and offset values act as 'cheap' alternatives to high-precision values, providing sufficient coding performance with minimal memory overhead, thereby resolving the technical contradiction
2Measurement precision
If high precision probability estimation initialization is used, then symbol statistics approximation is improved, but implementation complexity increases
Solution Approach 1:
The patent applies parameter changes by reducing the bit precision of slope and offset values used in probability estimation initialization. This reduction in precision parameter simplifies the implementation architecture and reduces computational complexity while maintaining adequate accuracy for video coding applications, thus resolving the contradiction between measurement precision and device complexity
Data Source
AI summary
A decoder includes an entropy decoder configured to derive a number of bins of the binarizations from the data stream using binary entropy decoding by selecting a context among different contexts and updating probability states associated with the different contexts, dependent on previously decoded portions of the data stream; a desymbolizer configured to debinarize the binarizations of the syntax elements to obtain integer values of the syntax elements; a reconstructor configured to reconstruct the video based on the integer values of the syntax elements using a quantization parameter, wherein the entropy decoder is configured to distinguish between 126 probability states and to initialize the probability states associated with the different contexts according to a linear equation of the quantization parameter, wherein the entropy decoder is configured to, for each of the different contexts, derive a slope and an offset of the linear equation from first and second four bit parts of a respective 8 bit initialization value.