CABAC dQP Binarization with Separate Sign and Unary Magnitude
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Solution Overview
Problem
Current video coding standards, such as HEVC, face inefficiencies in encoding Delta-QP (dQP) due to asymmetric binarization methods that do not fully utilize the symmetric distribution of dQP values, leading to suboptimal bit rate reduction and subjective quality.
Innovation Solution
The proposed solution involves a Separate Absolute Value and Sign (SAVS) binarization method within CABAC, where a flag indicates if dQP is zero, and if nonzero, the absolute value and sign are encoded separately using unary codes, allowing for a more efficient representation of dQP values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If asymmetric binarization method is used for dQP encoding, then the encoding process is simple, but the bit rate reduction is suboptimal
Solution Approach 1:
The dQP value is segmented into two separate components: sign information and absolute value information. The sign is encoded using a single bit (0 for positive, 1 for negative), while the absolute value is encoded using unary coding. 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 achieving better bit rate reduction while maintaining encoding simplicity.
2Ease of operation
If traditional unary coding is used for signed dQP, then encoding is straightforward, but it does not utilize the symmetric distribution property of dQP
Solution Approach 1:
The encoding process is segmented into two distinct steps: first encoding the sign bit, then encoding the absolute value using unary coding. This segmentation enables the encoder to take advantage of the symmetric distribution characteristic of dQP values, where |dQP| values follow a predictable distribution pattern. By separating the sign from the magnitude, the encoder can optimize the unary coding for the absolute value while using minimal bits for the sign, thereby improving coding efficiency without complicating the encoding process.
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.