CABAC dQP Binarization Using Separate Absolute Value and Sign
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Solution Overview
Problem
Existing video coding standards, such as HEVC, face challenges in achieving higher coding efficiency and reducing complexity, particularly in encoding Delta-QP (dQP) values using CABAC entropy coding.
Innovation Solution
The proposed solution involves a new binarization mode for dQP in CABAC that takes advantage of the symmetric distribution of dQP values. This is achieved by separately encoding the absolute value and sign of dQP using unary codes, allowing for more efficient representation of dQP values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional binarization methods are used for dQP in CABAC, then the encoding process is simpler, but the number of bits required increases and coding efficiency decreases
Solution Approach 1:
The patent segments the dQP value into two separate components: the absolute value and the sign. The absolute value is encoded using unary coding, while the sign is encoded using a separate binary flag. This segmentation allows each component to be optimized independently, reducing the total number of bits required while maintaining manageable encoding complexity.
Solution Approach 2:
The patent changes the parameter representation by separating the magnitude (absolute value) and direction (sign) of the dQP value. This parameter transformation enables more efficient bit allocation, where the unary-coded absolute value uses fewer bits on average compared to traditional binary representations, especially when dQP values are small and frequent.
2Loss of information
If more bits are used to encode dQP values, then precision is maintained, but the bit rate increases and storage efficiency decreases
Solution Approach 1:
The patent applies partial action by using unary coding for the absolute value, which uses a number of bits proportional to the magnitude. For small dQP values (which occur frequently), this uses minimal bits, while still maintaining full precision when needed. The sign bit adds only one additional bit regardless of the magnitude, achieving efficient partial representation.
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.