CABAC dQP Coding With SAVS for Symmetric Bit Reduction
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Solution Overview
Problem
Current Delta-QP coding in High Efficiency Video Coding (HEVC) standards, specifically within Context-Based Adaptive Binary Arithmetic Coding (CABAC), does not fully leverage the symmetric distribution of delta quantization parameter (dQP) values, leading to suboptimal bit rate efficiency and complexity.
Innovation Solution
The proposed solution involves a new binarization method called Separate Absolute Value and Sign (SAVS) for dQP coding, where a flag indicates if dQP is zero, and if nonzero, the absolute value and sign are separately encoded using unary codes, allowing for more efficient representation of symmetric dQP distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the current HM 3.0 binarization method is used for dQP coding, then the coding process is simple, but the bit rate efficiency is suboptimal because it does not leverage 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 bit rate efficiency without significantly increasing coding complexity.
2Productivity
If unary codes are used to map signed dQP to unsigned codenumber as in HM 3.0, then the implementation is straightforward, but different lengths are assigned to nonzero dQP with the same absolute values, leading to inefficiency
Solution Approach 1:
Different encoding strategies are applied to different parts of the dQP value based on its properties. The absolute value component is encoded using unary codes which are efficient for small magnitudes, while the sign component is encoded using a simple sign bit. This local quality approach ensures that the most probable values (small magnitudes) are encoded with the fewest bits, maximizing coding efficiency while keeping the overall binarization process relatively simple.
Data Source
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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.