Chroma Quantization Parameter Adjustment for HDR Video Coding
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Solution Overview
Problem
Chroma artifacts are more visible in high dynamic range (HDR) content when encoding with standard dynamic range (SDR) coding techniques, and existing methods for reducing these artifacts either impact coding efficiency or require additional bits for signaling.
Innovation Solution
Determine a chroma quantization parameter (QP) based on video characteristics using a first and second function, applying dynamic range adjustment (DRA) to improve coding efficiency while reducing chroma artifacts in HDR and wide color gamut (WCG) content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard dynamic range (SDR) coding techniques are used for high dynamic range (HDR) content, then coding efficiency is maintained, but chroma artifacts become more visible
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the chroma quantization parameter (QP) based on the luma QP value and picture characteristics. Specifically, it uses a first function to determine an intermediate chroma QP offset value from the luma QP, then applies a second function to determine the final chroma QP value. This adaptive parameter adjustment reduces chroma artifacts in HDR content while maintaining coding efficiency, resolving the contradiction between artifact visibility and coding performance.
2Reliability
If chroma quantization parameter is adjusted to reduce chroma artifacts, then chroma artifact visibility is reduced, but additional bits for signaling are required
Solution Approach 1:
The patent introduces an intermediate chroma QP offset value as a mediator between the luma QP and the final chroma QP. This intermediate value serves as a bridge that allows the chroma QP to be adaptively adjusted based on luma characteristics without requiring direct signaling of the final chroma QP value. The intermediate offset acts as a compact representation that reduces the signaling overhead while still enabling effective chroma artifact reduction.
3Reliability
If dynamic range adjustment is applied to reduce chroma artifacts, then chroma artifact visibility is reduced, but coding complexity increases
Solution Approach 1:
The patent segments the chroma QP determination process into two distinct functional stages: a first function that computes an intermediate chroma QP offset value from the luma QP and picture characteristics, and a second function that determines the final chroma QP value from the intermediate offset. This segmentation allows each function to be optimized independently and simplifies the overall implementation by breaking down the complex adaptive adjustment into manageable, modular steps.
Data Source
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AI summary
Techniques for decoding video data include determining a picture quantization parameter (QP) value of the picture of video data, determining an intermediate chroma QP offset value for a chroma QP value based on the picture QP value and a first function based on video characteristics of the picture of video data, determining the chroma QP value with a second function of the intermediate chroma QP offset value, and decoding the picture of video data using the chroma QP value.