Unified Rice Parameter Lookup Table for Video Encoding
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Solution Overview
Problem
The existing VVC Draft 5 uses two separate lookup tables for determining the Rice parameter, which increases memory usage and complexity, and has a limited dynamic range for transform skip, making it less responsive to wider changes in residual coding values.
Innovation Solution
A unified Rice parameter lookup table is used independently of transform skip, with an extended dynamic range of 0 to 3, reducing memory usage and simplifying the process by eliminating the need for separate tables and enhancing responsiveness to residual coding variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate lookup tables are used for transform skip and non-transform skip cases, then the Rice parameter determination can be tailored for each case, but memory usage and device complexity increase
Solution Approach 1:
The patent merges two separate lookup tables (one for transform skip case and one for non-transform skip case) into a single unified lookup table. The table is indexed by a combined key that includes both the absolute level and a transform skip flag, allowing the system to retrieve the appropriate Rice parameter for any combination of absolute level and transform skip status from a single table structure, thereby reducing memory usage and simplifying the implementation while maintaining the ability to provide optimized parameters for each case
Solution Approach 2:
The unified lookup table serves multiple functions simultaneously: it provides Rice parameter determination for both transform skip and non-transform skip cases, and handles the full range of absolute level values. The table is designed with a universal structure that accommodates different coding modes through its indexing mechanism, eliminating the need for separate specialized tables while maintaining the specific optimization benefits for each case
2Productivity
If the lookup table dynamic range is limited, then memory usage is reduced, but responsiveness to wider changes in residual coding values deteriorates
Solution Approach 1:
The patent extends the lookup table to accommodate a wider dynamic range by introducing an additional dimension to the table structure. Instead of having a limited single-dimensional table, the unified table is organized with both absolute level and transform skip status as indexing dimensions, creating a multi-dimensional lookup structure that can respond to wider variations in residual coding values while maintaining efficient memory access through direct indexing
Data Source
AI summary
According to an embodiment, a method of selecting a Rice parameter for encoding a video bitstream using at least one processor includes obtaining an absolute level corresponding to a current transform block; determining whether transform skip is enabled; generating a lookup variable based on the absolute level and the determination of whether the transform skip is enabled; obtaining the Rice parameter from a lookup table based on the lookup variable; and encoding a residual subblock based on the Rice parameter.