Adaptive Color Transform in Video Coding Deblocking
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Solution Overview
Problem
Current video coding standards face challenges in efficiently managing motion vectors and deblocking filters, leading to inaccurate motion information and visual artifacts due to complex logic and misalignment of chroma QP usage in deblocking processes.
Innovation Solution
The proposed solution involves a method for video processing that uses adaptive color transform (ACT) and block-based delta pulse code modulation (BDPCM) coding, where deblocking filters are applied with chroma QP offsets derived from luma coding units and signaled in the bitstream, enabling flexible chroma QP table signaling and joint chroma residual coding to improve deblocking decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If chroma QP values are used independently in deblocking filter without alignment to luma information, then chroma processing flexibility is improved, but deblocking accuracy deteriorates due to misalignment with luma coding units
Solution Approach 1:
The patent applies local quality by deriving chroma QP offsets at the coding unit level based on corresponding luma coding unit information. Each chroma block's QP is adjusted according to its specific luma neighbor characteristics, allowing localized optimization of deblocking accuracy while maintaining chroma processing flexibility through CU-level customization.
Solution Approach 2:
The patent introduces luma coding unit information as an intermediary to bridge chroma QP derivation and deblocking filter operation. The luma QP values and coding unit characteristics serve as mediator parameters that guide chroma QP offset calculation, ensuring alignment between chroma and luma processing domains while enabling accurate deblocking decisions.
2Adaptability or versatility
If complex logic is used to manage motion vectors and deblocking filters, then coding flexibility is improved, but processing complexity increases leading to inaccurate motion information and visual artifacts
Solution Approach 1:
The patent merges the management of motion vectors and deblocking filter parameters into a unified framework based on coding unit characteristics. By combining motion vector derivation with chroma QP offset calculation using the same luma-based reference system, the patent reduces overall system complexity while maintaining coding flexibility through integrated processing.
Solution Approach 2:
The patent simplifies complex deblocking logic by changing the parameter derivation approach from independent chroma-based parameters to luma-aligned parameters. The chroma QP offsets are calculated by modifying luma QP values based on coding unit characteristics, reducing the number of independent parameters and simplifying the overall processing logic while maintaining flexibility.
3Adaptability or versatility
If chroma QP offsets are not derived from luma coding units, then chroma processing independence is improved, but visual quality deteriorates due to misalignment with luma information
Solution Approach 1:
The patent maintains chroma processing independence at the block level while achieving visual quality alignment through local QP offset derivation. Each chroma coding unit receives customized QP offsets based on its specific luma neighbor characteristics, allowing independent chroma processing decisions while ensuring visual quality through locally optimized parameter alignment.
Solution Approach 2:
The patent introduces dynamic chroma QP offset adjustment based on luma coding unit characteristics. The QP offsets are not fixed but dynamically calculated according to the specific luma blocks adjacent to each chroma block, enabling adaptive alignment with luma information while preserving chroma processing independence through flexible, data-driven parameter adjustment.
Data Source
AI summary
A method of video processing, including performing a conversion between a video unit of a video and a bitstream representation of the video, wherein the conversion includes applying a deblocking filter to at least some samples on boundaries of the video unit, wherein deblocking quantization parameter (QP) values used in the deblocking filter are determined according to a rule, and wherein the rule specifies that whether the deblocking QP values are equal to dequantization QP values for the video unit is based on whether an adaptive color transform (ACT) mode is applied to the video unit.