Transform Coefficient Sign Prediction for Efficient Video Coding
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Solution Overview
Problem
Existing video coding systems face inefficiencies in sign coding of transform coefficients, particularly in the context of versatile video coding (VVC), which affects compression efficiency and quality.
Innovation Solution
Implement joint sign prediction for transform coefficients by determining a hypothesis that minimizes cost based on boundary pixel comparisons and reconstructing signs using decoded residues, adapting the transform coefficient region and index range according to coding context.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional sign coding methods are used for transform coefficients, then the coding process is simple, but compression efficiency is insufficient
Solution Approach 1:
The patent applies preliminary action by performing joint sign prediction before final sign coding. The encoder predicts signs of transform coefficients based on neighboring coefficients and previously decoded signs, preparing predicted sign values that are then compared with actual signs to generate sign residues. This preliminary prediction step reduces the entropy of sign data before entropy coding, thereby improving compression efficiency without adding excessive complexity.
Solution Approach 2:
The patent implements feedback mechanisms where the encoder transmits sign residue information and prediction mode indicators to the decoder. The decoder uses this feedback to reconstruct signs by combining predicted signs with received sign residues. This feedback loop ensures accurate reconstruction while allowing the system to adapt to different video content characteristics, improving overall compression performance.
2Measurement precision
If joint sign prediction is implemented with multiple hypotheses, then sign coding accuracy improves, but computational complexity increases
Solution Approach 1:
The patent applies partial action by implementing joint sign prediction selectively rather than uniformly across all transform coefficients. The system determines a prediction mode based on video content characteristics and applies sign prediction only to relevant coefficients or regions. This selective approach maintains high prediction accuracy where needed while reducing computational complexity in regions where prediction provides minimal benefit.
Solution Approach 2:
The patent changes parameters dynamically by adjusting the prediction mode and hypothesis selection based on video content analysis. The system evaluates different prediction hypotheses and selects the one that provides the best trade-off between accuracy and complexity for each block or region. This parameter adaptation allows the system to achieve high prediction accuracy when beneficial while avoiding unnecessary computational overhead.
Data Source
AI summary
A method and apparatus for joint sign prediction of transform coefficients of residual blocks in a video coding system are disclosed. At the encoder side, a transform coefficient region or an index value range is determined according to coding context associated with the current block. A set of signs associated with a set of selected transform coefficients are determined for joint sign prediction are determined according to the transform coefficient region or the index value range. Joint sign prediction for the set of signs is determined by selecting a hypothesis from a group of hypotheses for the set of signs that achieves a minimum cost. The sign prediction is then used for coding the set of signs. A corresponding method and apparatus for the decoder side is also disclosed.