Transform Coefficient Sign Prediction Under Transform Skip
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in transform coefficient sign prediction, particularly when transform skip is applied, leading to suboptimal compression ratios and increased computational complexity.
Innovation Solution
Implementing a method for transform coefficient sign prediction that adapts based on the use of one-dimensional or two-dimensional transform skips, enabling independent prediction of coefficient signs in different dimensions and disabling prediction when transform skip is used, thereby optimizing compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If transform coefficient sign prediction is performed using traditional methods, then compression ratio is improved, but computational complexity increases when transform skip is applied
Solution Approach 1:
The patent implements dynamic adaptation of sign prediction methods based on transform skip application. When transform skip is detected, the system switches to a simplified prediction approach that uses fewer computational operations, while maintaining effective compression. This dynamic adjustment resolves the contradiction by making computational complexity conditional rather than fixed.
Solution Approach 2:
The patent changes the prediction parameters adaptively - using different prediction strategies (e.g., different reference sample selections or prediction formulas) depending on whether transform skip is applied. This parameter change allows the system to optimize between compression efficiency and computational load for different coding scenarios.
2Productivity
If transform skip is applied in both dimensions, then compression efficiency is improved, but sign prediction accuracy deteriorates with traditional prediction methods
Solution Approach 1:
The patent segments the sign prediction process into different dimensional components when transform skip is applied. By treating horizontal and vertical dimensions separately and applying appropriate prediction methods to each, the system maintains prediction accuracy even when overall transform skip is used, thereby resolving the contradiction between compression efficiency and prediction accuracy.
Solution Approach 2:
The patent applies different prediction quality levels to different regions or dimensions based on local characteristics. When transform skip is applied, the system adjusts the prediction approach locally to maintain accuracy where needed while allowing greater compression where appropriate, thus resolving the contradiction between compression efficiency and prediction accuracy.
Data Source
AI summary
An example apparatus includes processing circuitry that is configured to receive a coded video stream including a current block that is associated with a transform block, and determine whether a transform skip is used in the transform block. In response to a determination that the transform skip is not used in the transform block, the processing circuitry is configured to perform a first transform coefficient sign prediction in which (i) first signs of a first plurality of transform coefficients are predicted based on a first plurality of neighboring samples, and (ii) second signs of a second plurality of transform coefficients are predicted based on a second plurality of neighboring samples. The processing circuitry is further configured to reconstruct the current block based on the first plurality of transform coefficients and the second plurality of transform coefficients.