Hybrid Entropy Coding with Partitioned VLC and PIPE Streams
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing entropy coding methods face challenges in achieving a balance between coding complexity and compression efficiency, particularly when dealing with time-varying source statistics and skewed probability distributions, with Huffman codes being inefficient for dominant alphabet values and arithmetic coding being too complex.
Innovation Solution
A hybrid entropy coding scheme that decomposes syntax elements into multiple partitions, using VLC encoding for symbols with suitable statistics and PIPE encoding for others, allowing for a better tradeoff between coding complexity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Huffman codes are used for entropy coding, then the implementation is efficient with variable-length code tables, but the redundancy is substantial when dealing with dominant alphabet values and the adaptation to time-varying statistics is demanding
Solution Approach 1:
The patent segments the source alphabet into multiple subsets based on probability characteristics. Different Huffman code tables are constructed for different subsets, allowing efficient coding of dominant symbols while maintaining adaptability to time-varying statistics. This segmentation resolves the contradiction by enabling both implementation efficiency (through VLC tables) and reduced redundancy (through specialized coding for dominant symbols).
Solution Approach 2:
The patent implements dynamic adaptation of Huffman code tables based on time-varying source statistics. The code tables are updated periodically or adaptively to reflect changing symbol probabilities, allowing the system to maintain low redundancy even as the underlying distribution changes over time. This dynamic approach resolves the contradiction between implementation efficiency and adaptability to time-varying statistics.
2Adaptability or versatility
If arithmetic coding is used for entropy coding, then the handling of adaptive and higher-order probability modeling is more consistent and adequate, but the implementation complexity is substantially higher than VLC
Solution Approach 1:
The patent segments the coding task into multiple independent Huffman coding operations, each handling a specific subset of symbols with particular probability characteristics. This segmentation allows the use of simpler VLC tables while still achieving adaptive probability modeling by selecting appropriate code tables based on observed statistics. The approach resolves the contradiction by providing adaptability through multiple specialized code tables rather than through complex arithmetic coding operations.
Solution Approach 2:
The patent changes the parameter of code table selection based on observed source statistics. By monitoring symbol frequencies and selecting from multiple pre-computed Huffman code tables with different properties, the system achieves adaptive probability modeling without the computational complexity of arithmetic coding. This parameter-based selection resolves the contradiction between adaptability and implementation complexity.
3Adaptability or versatility
If multiple sets of VLC tables are used for higher-order probability modeling, then the modeling capability is improved, but the implementation complexity increases
Solution Approach 1:
The patent segments the symbol space into hierarchical subsets based on probability magnitude and relationships. Multiple VLC tables are organized in a hierarchy where coarser tables handle more frequent symbols and finer tables handle less frequent symbols. This hierarchical segmentation enables higher-order probability modeling by capturing dependencies at different levels while controlling implementation complexity through the structured organization of code tables.
Data Source
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 VLC 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, 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.