Variable Length Coding Mapping via Tree Hierarchy Levels
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Solution Overview
Problem
Traditional video codecs face challenges in efficiently adapting variable length code words to changing statistical probabilities in video sequences, leading to suboptimal compression and increased complexity in maintaining adaptive coding.
Innovation Solution
The method involves determining mapping between syntax elements and code words using a hierarchy level in a tree structure, allowing for adaptive sorting tables and context-dependent coding, where different VLC tables are used based on transform sizes and hierarchy levels to improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional fixed VLC tables are used for encoding syntax elements, then the encoding process is simple, but the compression efficiency deteriorates when statistical probabilities change in video sequences
Solution Approach 1:
The patent implements dynamic adaptation of VLC tables by maintaining multiple sorting tables that can be selected based on current video content statistics. The encoder dynamically updates the probability model and selects appropriate VLC tables from a predefined set, allowing the coding system to adapt to changing statistical characteristics in video sequences while maintaining manageable complexity through a finite set of pre-defined tables.
Solution Approach 2:
The patent changes the parameter set by maintaining multiple predefined VLC tables with different code word assignments. Instead of continuously generating new code words, the system selects from a finite set of tables with varying parameters (code word lengths and assignments), changing the active table parameter based on detected statistical characteristics of the video content to optimize compression efficiency.
2Productivity
If adaptive sorting tables are implemented to track changing statistics, then coding efficiency improves, but the complexity of maintaining adaptive coding increases
Solution Approach 1:
The system dynamically adapts by updating probability models and selecting from multiple predefined VLC tables based on current video content characteristics. This dynamic selection approach allows the system to track changing statistics and maintain high coding efficiency without implementing complex real-time code word generation, as the adaptation is achieved through table selection rather than table construction.
Solution Approach 2:
The patent uses a set of predefined VLC tables that can be quickly swapped based on content characteristics. Instead of maintaining and updating a single complex adaptive table, the system uses multiple simpler, pre-configured tables that are selected and discarded (or switched to) based on current needs, reducing the complexity of maintaining adaptive coding structures.
3Productivity
If context-dependent coding with multiple VLC tables is used, then compression performance improves, but the complexity of selecting and managing tables increases
Solution Approach 1:
The system dynamically selects from multiple VLC tables based on detected context characteristics such as transform sizes and hierarchy levels in the video data. This dynamic context-dependent selection allows the system to optimize compression performance for different data types and patterns while managing complexity through rule-based selection criteria rather than complex optimization algorithms.
Solution Approach 2:
The patent applies different VLC tables to different local contexts within the video data, such as different transform block sizes or hierarchy levels. Each local region or syntax element type can use the most appropriate VLC table for its characteristics, improving overall compression performance while managing complexity through localized, context-specific table selection rather than global table management.
Data Source
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AI summary
A method comprising receiving a syntax element to be encoded as a code word of a set of code words, determining a mapping between the syntax element and the code word on the basis of a hierarchy level in a tree structure, using the mapping to obtain the code word, and updating the mapping is disclosed.