Entropy Decoder Context Initialization with 8-Bit State Mapping
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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 representation of video content statistics, affecting compression efficiency and memory usage.
Innovation Solution
The proposed solution involves reducing the accuracy of slope and offset values for context-adaptive binary entropy coding, allowing for a compromise between coding efficiency and complexity by deriving these values from a linear equation of the quantization parameter, with each context using four-bit parts of an 8-bit initialization value to reduce memory demands and improve coding efficiency.
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 accuracy (e.g., 8-bit or higher) to reduced accuracy (e.g., 4-bit or lower). This parameter change directly reduces memory storage requirements while the patent demonstrates that the reduced precision values still adequately represent video content statistics, thereby maintaining acceptable coding efficiency without the high memory cost
Solution Approach 2:
The patent applies different precision levels to different contexts. Specifically, it uses reduced accuracy slope and offset values for contexts where high precision is not critical, while potentially maintaining higher precision for contexts where it matters more. This local differentiation optimizes the balance between overall coding efficiency and memory usage by not uniformly applying high precision across all contexts
2Measurement precision
If high accuracy slope and offset values are used for probability estimation initialization, then representation accuracy of video content statistics is improved, but implementation complexity increases
Solution Approach 1:
The patent changes the precision parameter of slope and offset values from high accuracy to reduced accuracy. This parameter change simplifies the initialization process and reduces computational complexity while the patent demonstrates that the reduced precision values still adequately represent video content statistics, thereby maintaining acceptable representation accuracy without the high implementation cost
3Device complexity
If reduced accuracy slope and offset values are used, then memory requirements are reduced, but coding efficiency may deteriorate
Solution Approach 1:
The patent changes the precision parameter to reduced accuracy values, which directly reduces memory requirements. The patent then evaluates and adjusts this parameter change to ensure that coding efficiency does not deteriorate significantly, finding an optimal balance point where memory usage is reduced while coding performance remains acceptable
Solution Approach 2:
The patent applies reduced accuracy values which is a partial reduction from the original high accuracy values. This partial action is sufficient to achieve the goal of reducing memory requirements while not excessively degrading coding efficiency, as the reduced precision values still capture the essential statistical characteristics of video content
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.