Sign Bit Hiding in Video Coding Transform Coefficients
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Solution Overview
Problem
Existing video coding techniques face challenges in efficiently embedding and deriving the sign of transform coefficients, leading to increased bitrate and potential quality degradation due to the limitations of current sign bit hiding methods.
Innovation Solution
A processing circuitry is configured to determine whether to embed or derive the sign of a transform coefficient based on a function of transform coefficients and the number of coefficients exceeding a threshold, allowing for selective sign bit hiding while maintaining acceptable distortion, and using a lookup table for efficient threshold storage and application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sign bit hiding is applied to all transform coefficients, then coding efficiency is improved, but picture quality degradation increases
Solution Approach 1:
The patent applies different sign bit hiding strategies to different transform coefficient blocks based on their characteristics. Specifically, it evaluates each block to determine whether sign hiding should be applied, using criteria such as the number of non-zero coefficients and their magnitude distribution. This local adaptation allows the system to maximize compression efficiency in blocks where sign hiding is beneficial while preserving picture quality in blocks where it would cause excessive distortion.
Solution Approach 2:
The patent dynamically adjusts the sign bit hiding parameters based on block characteristics. It uses thresholds and evaluation functions that adapt to the specific properties of each transform coefficient block, such as the count of non-zero coefficients and their relative magnitudes. This parameter adaptation enables the system to optimize the balance between compression and quality for each block individually.
2Loss of energy
If sign bit hiding is applied to more transform coefficients, then bitrate reduction is improved, but distortion increases
Solution Approach 1:
The patent applies sign bit hiding partially rather than universally. It selectively applies the technique only to transform coefficient blocks that satisfy specific criteria, such as having a sufficient number of non-zero coefficients with magnitudes above certain thresholds. This partial application ensures that sign hiding is used only where it provides net benefit, avoiding excessive distortion in blocks where the overhead or distortion would outweigh the compression gains.
3Device complexity
If existing sign bit hiding methods are used, then implementation simplicity is maintained, but coding efficiency is limited
Solution Approach 1:
The patent performs preliminary evaluation of transform coefficient blocks before applying sign bit hiding. It pre-calculates characteristics such as the number of non-zero coefficients and their magnitude distributions to determine suitability for sign hiding. This preliminary action allows the system to make informed decisions about where to apply sign hiding, improving coding efficiency while maintaining relatively simple implementation through use of standard evaluation functions and thresholds.
Data Source
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AI summary
The present disclosure relates to provision of a mechanism for deciding whether and/or for which set of transformation coefficients resulting from a transformation of some source signal a sign of a current transformation coefficient may be embedded into a value of a function of that set of transformation coefficients. In particular, the decision is based on a condition including evaluating a second function of the transform coefficient values in the set of transform coefficients and a number of those transform coefficients in the set which are larger than a coefficient value threshold. The corresponding decoder for is also provided.