Video Coding Transform Coefficient Level Signaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current video coding standards, such as HEVC, face limitations in efficiently encoding transform coefficient level values, particularly in handling coefficient levels greater than one, which affects compression efficiency and bitstream generation.
Innovation Solution
The proposed solution involves a method for encoding and decoding video data by determining whether a coefficient level value is equal to one, greater than one, or greater than or equal to three, using specific flag combinations to signal these values, thereby optimizing the encoding process and reducing the number of context-coded bins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current video coding standards (HEVC) are used to encode transform coefficient level values, then the encoding process is standardized and compatible, but compression efficiency is insufficient particularly for coefficient levels greater than one
Solution Approach 1:
The encoding process is segmented into multiple passes: first determining whether coefficient level is greater than one using a first flag, then determining whether it is greater than or equal to three using a second flag. This segmentation allows efficient handling of different coefficient level ranges with appropriate flag combinations, improving compression efficiency without excessive complexity.
Solution Approach 2:
Different encoding strategies are applied locally based on the coefficient level value. For coefficient levels equal to one, specific flag combinations are used; for levels greater than one but less than three, different flag combinations are used; and for levels greater than or equal to three, additional flags are employed. This localized approach optimizes compression for each specific case.
2Measurement precision
If more context-coded bins are used to accurately signal coefficient level values, then encoding precision is improved, but the bin-to-bit ratio deteriorates
Solution Approach 1:
Instead of using full precision encoding for all coefficient levels, the invention uses partial action by employing a hierarchical flag system. The first flag indicates whether the level is greater than one, the second flag indicates whether it is greater than or equal to three, and only when necessary are additional flags used. This partial encoding approach maintains sufficient precision while reducing the number of bins required, thereby improving the bin-to-bit ratio.
3Device complexity
If a simplified flag system is used to signal coefficient levels, then the number of context-coded bins is reduced, but the ability to accurately represent all coefficient level values deteriorates
Solution Approach 1:
The flag system is structured as nested conditions where the first flag (coefficient level greater than one) contains within it the logic for the second flag (coefficient level greater than or equal to three). This nested structure allows the system to represent all coefficient level values accurately while using a compact sequence of flags, thereby reducing the number of context-coded bins needed without sacrificing precision.
Data Source
AI summary
This disclosure relates to video coding and more particularly to techniques for performing entropy coding. According to an aspect of an invention, a parity level flag specifying a parity of a transform coefficient level at a scanning position is decoded if a value of a second absolute level greater flag is equal to a first value.