Merged Chroma Block CfL Prediction for Small-Block Video Coding
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in chroma prediction, particularly in scenarios where chroma blocks are smaller than a certain size, leading to increased bit usage and reduced compression efficiency.
Innovation Solution
Implementing chroma from luma (CfL) prediction by combining multiple chroma blocks into a larger block and using neighbor luma samples to generate a prediction average, thereby reducing the number of bits required for chroma block encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional chroma prediction methods are used for small chroma blocks, then chroma prediction can be performed, but bit usage increases and compression efficiency decreases
Solution Approach 1:
The patent merges multiple small chroma blocks into a single larger chroma block that is predicted together using luma samples. This merging approach allows the use of chroma from luma (CfL) prediction, which significantly reduces the number of bits required to encode chroma information while maintaining or improving compression efficiency. The merged chroma block is predicted from neighboring luma blocks rather than being encoded independently.
Solution Approach 2:
The patent introduces luma samples as an intermediary to predict chroma values. Instead of directly encoding chroma blocks or using traditional chroma prediction, the method uses neighboring luma block samples as an intermediate reference to generate chroma predictions through the CfL algorithm. This intermediary approach leverages the strong correlation between luma and chroma channels to reduce chroma bit requirements.
2Productivity
If chroma blocks are processed independently, then prediction can be applied to each block, but the complexity of processing increases for small blocks
Solution Approach 1:
The patent combines multiple small chroma blocks into a single merged chroma block that is processed together. This merging reduces the number of separate prediction operations required, thereby reducing processing complexity while improving overall compression efficiency. The merged block is predicted from neighboring luma blocks in a single operation rather than processing each small chroma block independently.
Solution Approach 2:
The patent changes the prediction parameter approach by using luma sample values as the basis for chroma prediction instead of traditional chroma-based prediction methods. This parameter change enables the use of CfL prediction, which simplifies the processing by leveraging the relationship between luma and chroma channels, thereby reducing the complexity of handling small chroma blocks.
Data Source
AI summary
Video processing devices and methods are disclosed to combine chroma blocks into a combined chroma block, determine neighbor luma samples of one or more luma blocks corresponding to the combined chroma block, average the reconstructed neighbor luma samples to generate a neighbor luma average, and perform a chroma from luma (CfL) prediction for the chroma blocks based on the neighbor luma average; and to compare a size of a chroma block with at least one size threshold and/or a transform unit (TU) depth of the chroma block with a TU depth of a corresponding luma block; determine a type of CfL prediction process for the chroma block based on the comparison; and perform a CfL prediction process for the chroma block according to the type of CfL prediction process.