Entropy Encoding with Partitioned Syntax Element Coding
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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 existing methods like Huffman codes and arithmetic coding have limitations in adaptability and complexity.
Innovation Solution
The proposed solution involves decomposing syntax elements into multiple partitions and using a combination of VLC and PIPE coding, where source symbols are subdivided into substreams for efficient encoding and decoding, allowing for better adaptation to statistics and improved compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Huffman codes with VLC tables are used, then implementation is simple and easy to realize, but adaptability to time-varying source statistics is poor and redundancy is substantial
Solution Approach 1:
The patent implements dynamic adaptation of Huffman codes by maintaining multiple VLC tables corresponding to different probability distribution states and dynamically selecting the appropriate table based on current source statistics. This allows the coding system to adapt to time-varying source characteristics while maintaining the simplicity of Huffman coding structure.
Solution Approach 2:
The patent changes the parameter of codebook selection by maintaining multiple VLC tables with different code assignments optimized for different probability distributions. The system dynamically adjusts which VLC table is used based on the current statistical properties of the source, thereby adapting to changing conditions without changing the fundamental Huffman coding mechanism.
2Adaptability or versatility
If arithmetic coding is used, then adaptability to time-varying source statistics and higher-order probability modeling is improved, but implementation complexity increases substantially
Solution Approach 1:
The patent segments the probability space into multiple discrete intervals and assigns specific VLC codes to each interval. This segmentation approach captures the adaptability benefits of arithmetic coding by creating multiple specialized codebooks for different probability ranges, while avoiding the continuous arithmetic operations that cause complexity.
Solution Approach 2:
The patent uses pre-computed VLC tables that can be quickly switched between without requiring complex real-time computation. Each VLC table is a simplified, pre-prepared codebook optimized for specific probability conditions, replacing the need for complex arithmetic coding operations while maintaining adaptability.
3Device complexity
If PIPE coding is used, then coding complexity is reduced compared to arithmetic coding, but compression efficiency is still not optimal for all probability distributions
Solution Approach 1:
The patent creates a universal Huffman coding framework that can handle multiple probability distribution types by maintaining multiple VLC tables. Each table is optimized for specific distribution characteristics, allowing the system to achieve high compression efficiency across various scenarios while maintaining the low complexity of Huffman coding.
Solution Approach 2:
The patent combines multiple VLC tables into a composite coding system where each table represents a different probability distribution model. The system composes the final code by selecting the appropriate table based on current statistics, achieving both low complexity and high efficiency through this composite structure.
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 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.