Adaptive Color Transform for 4:4:4 Video Residual Coding
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Solution Overview
Problem
Existing video coding standards, such as VVC, struggle to efficiently encode and decode 4:4:4 chroma format videos due to insufficient consideration of correlations among the three color components, leading to suboptimal compression efficiency and increased data redundancy.
Innovation Solution
Implementing adaptive color-space transform (ACT) for residuals in both lossy and lossless coding modes, enabling tools like 8-tap interpolation filters, position-dependent intra prediction combination (PDPC), multi-reference line (MRL), and sub-partition prediction (ISP) for chroma components, and using a unified design for both luma and chroma components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing video coding standards are used for 4:4:4 chroma format, then compatibility with current standards is maintained, but compression efficiency is insufficient and data redundancy is high
Solution Approach 1:
The patent applies parameter changes by transforming the color space from RGB to YCgCo for residual data processing. This color space transformation changes the parameters of the data representation to exploit correlations among color components, thereby improving compression efficiency and reducing redundancy in 4:4:4 chroma format video coding.
2Productivity
If adaptive color-space transform is applied to exploit correlations among color components, then coding efficiency improves, but processing complexity increases
Solution Approach 1:
The patent applies local quality by enabling the adaptive color-space transform selectively based on local characteristics of the video data. The transform is applied only when beneficial, with different transform matrices selected for different regions or conditions, thereby improving coding efficiency while managing processing complexity through localized application rather than global enforcement.
Data Source
AI summary
An electronic apparatus performs a method of decoding video data that includes: if the adaptive color transform (ACT) is enabled for the residuals of a coding unit, receiving, from information in a bitstream, the adjustment values applied to the quantization parameters for de-quantization, and the coefficients for the residuals of the coding unit; reconstructing the residuals of the coding unit by applying the de-quantization and inverse transform to the received coefficients for the residuals of the coding unit; and if the residuals of the coding unit have been coded using the ACT, modifying the reconstructed residuals of the coding unit by applying an inverse ACT to convert the reconstructed residuals of the coding unit from the YCgCo color space to the original color space based on one same inverse ACT matrix that is applied to the one coding unit being coded either in a lossy or lossless coding mode.