CABAC Delta-QP Binarization Using SAVS for Bit-Efficient Encoding
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Solution Overview
Problem
Current High Efficiency Video Coding (HEVC) standards, particularly in Context-Based Adaptive Binary Arithmetic Coding (CABAC), face inefficiencies in encoding Delta-QP (dQP) due to asymmetric binarization methods that do not fully leverage the symmetric distribution of dQP values, leading to suboptimal bit allocation and coding complexity.
Innovation Solution
The proposed solution involves a Separate Absolute Value and Sign (SAVS) binarization method, where a flag indicates non-zero dQP, and either the absolute value or sign of dQP is mapped using unary codes, allowing for separate encoding and combination of binary strings, optimizing bit usage based on the symmetric probability distribution of positive and negative dQPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If asymmetric binarization method is used for dQP encoding, then the encoding process is simple, but the coding efficiency is suboptimal due to not leveraging the symmetric distribution of dQP values
Solution Approach 1:
The dQP value is segmented into two separate components: the absolute value and the sign. The absolute value is encoded using unary codes, while the sign is encoded separately using a dedicated sign bit. This segmentation allows the encoder to exploit the symmetric distribution property of dQP values, where positive and negative values with the same magnitude have similar probabilities, thereby improving coding efficiency without significantly increasing complexity.
2Loss of information
If separate encoding of absolute value and sign is implemented, then bit allocation is optimized based on symmetric distribution, but the encoding process becomes more complex
Solution Approach 1:
The encoding approach changes the parameter representation by separating the magnitude (absolute value) and direction (sign) of dQP. The absolute value is encoded using unary codes which are efficient for small integers, while the sign is encoded using a single bit. This parameter change aligns with the statistical properties of dQP distribution and optimizes bit allocation, with the added complexity being minimal and manageable.
3Quantity of substance
If unary codes are used for mapping absolute value, then the number of bits is reduced for small absolute values, but the encoding structure becomes more complex
Solution Approach 1:
Unary coding is applied partially - only to the absolute value component of dQP, while the sign is handled separately with a simple bit. This partial application of unary coding achieves bit reduction for the magnitude component (which typically has smaller values) without requiring complete restructuring of the entire encoding system, thus balancing bit efficiency with structural simplicity.
Data Source
AI summary
Video coding systems or apparatus utilizing context-based adaptive binary arithmetic coding (CABAC) during encoding and/or decoding, are configured according to the invention with an enhanced binarization of non-zero Delta-QP (dQP). During binarization the value of dQP and the sign are separately encoded using unary coding and then combined into a binary string which also contains the dQP non-zero flag. This invention capitalizes on the statistical symmetry of positive and negative values of dQP and results in saving bits and thus a higher coding efficiency.