Partitioned Entropy Coding for Higher Compression Efficiency
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Solution Overview
Problem
Current entropy coding schemes face challenges in achieving a balance between coding complexity and compression efficiency, particularly when dealing with time-varying source statistics and higher-order probability modeling, as they often require substantial algorithmic complexity and implementation costs.
Innovation Solution
The proposed solution involves decomposing the value range of syntax elements into a sequence of partitions, where components within each partition are coded separately using Variable-Length Coding (VLC) and Arithmetic Coding, allowing for a more efficient trade-off between coding complexity and compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If arithmetic coding is used to achieve better compression efficiency for time-varying source statistics and higher-order probability modeling, then compression efficiency is improved, but coding complexity increases substantially
Solution Approach 1:
The patent segments the probability distribution into multiple discrete probability levels (e.g., 8 levels from 1/256 to 128/256). Each level has a dedicated VLC table, allowing the system to select the most appropriate coding scheme for each symbol based on its probability level. This segmentation enables the system to achieve compression efficiency close to arithmetic coding while maintaining the simplicity of VLC by avoiding the need to handle all possible probability values continuously.
Solution Approach 2:
The patent applies different coding strategies to different parts of the probability space. For high-probability symbols (levels 1-4), simpler VLC tables are used, while for lower-probability symbols (levels 5-8), more detailed VLC tables provide better compression. This local differentiation allows the system to optimize compression efficiency for each probability range without uniformly increasing complexity across all symbols.
2Ease of manufacture
If Huffman codes with VLC tables are used to reduce coding complexity, then ease of implementation is improved, but compression efficiency deteriorates when dealing with time-varying source statistics and highly skewed probability distributions
Solution Approach 1:
The patent implements dynamic selection among multiple VLC tables based on the probability level of each symbol. Instead of using a single static VLC table, the system maintains 8 different VLC tables corresponding to 8 probability levels. The appropriate table is selected dynamically for each symbol based on its estimated probability level, allowing the coding scheme to adapt to time-varying source statistics while maintaining the simplicity of VLC implementation.
Solution Approach 2:
The patent changes the parameter of the coding scheme by introducing multiple VLC tables with different code assignments optimized for different probability levels. Each VLC table is specifically designed for its corresponding probability level, allowing the system to change the coding parameters (which VLC table to use) based on the symbol's probability characteristics, thereby improving compression efficiency without changing the fundamental VLC approach.
3Productivity
If multiple sets of VLC tables are used for higher-order probability modeling, then compression efficiency is improved, but device complexity and implementation costs increase
Solution Approach 1:
The patent creates a universal VLC coding framework that handles higher-order probability modeling through a single unified structure. Instead of requiring separate coding mechanisms for different probability models, the system uses one universal approach: estimate the probability level, select the corresponding VLC table from the 8 available tables, and encode. This multi-functional VLC table set serves all higher-order probability modeling needs without requiring additional complex infrastructure.
Data Source
Figure 1A
Figure 1B~1C
Figure 2A
AI summary
Decomposing a value range of the respective syntax elements into a sequence of n partitions with coding the components of z laying within the respective partitions separately with at least one by VCL coding and with at least one by PIPE or entropy coding is used to greatly increase the compression efficiency at a moderate coding overhead since the coding scheme used may be better adapted to the syntax element statistics. Accordingly, in accordance with embodiments, syntax elements are decomposed into a respective number n of source symbols si with i=1...n, the respective number n of source symbols depending on as to which of a sequence of n partitions (1401-3) into which a value range of the respective syntax elements is sub-divided, a value z of the respective syntax elements falls into, so that a sum of values of the respective number of source symbols si yields z, and, if n>1; for all i=1...n-1, the value of si corresponds to a range of the ith partition.