Picture Block Prediction Samples for Low-Memory Chroma Coding
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Solution Overview
Problem
Existing video coding methods require significant internal memory for deriving prediction samples, particularly in formats like YUV4:2:0, which hinders hardware implementation.
Innovation Solution
The method determines a prediction sample of a picture block by acquiring the type of a current pixel string, using a reference pixel value based on the color sampling mode of the block, and ensuring the prediction sample's color sampling mode matches the block's, thereby reducing memory occupation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prediction samples are derived using conventional methods, then prediction accuracy is maintained, but internal memory size increases significantly
Solution Approach 1:
The patent extracts only the necessary chroma prediction samples from the full-resolution prediction block, deriving them at reduced resolution according to the color sampling mode. This selective extraction reduces memory occupation while maintaining the essential prediction functionality needed for accurate reconstruction.
Solution Approach 2:
The patent changes the resolution parameter of chroma prediction samples based on the color sampling mode (e.g., 4:2:0, 4:2:2). By adjusting the sampling resolution parameter, the system reduces memory requirements for storing prediction samples while adapting the prediction accuracy to the specific color format being used.
2Manufacturing precision
If full-resolution prediction samples are stored for all color components, then prediction quality is high, but memory occupation increases
Solution Approach 1:
The patent applies different quality levels to different color components based on their importance and the color sampling mode. Luma components are maintained at full resolution while chroma components are downsampled according to the sampling format (4:2:0, 4:2:2, etc.), optimizing the balance between prediction quality and memory usage by allocating resources locally to where they are most needed.
Solution Approach 2:
The patent performs partial derivation of chroma prediction samples only where needed according to the color sampling mode, rather than deriving all chroma samples at full resolution. This partial action approach maintains sufficient prediction quality for the specific color format while avoiding the excessive memory occupation that would result from full-resolution chroma prediction samples.
Data Source
AI summary
Some aspects of the disclosure provide a method for picture block prediction. For example, a type of a current pixel string where a current pixel in a current picture block is located is acquired. A reference pixel for the current pixel is determined according to the type of the current pixel string. A prediction sample of the current pixel is obtained according to a color sampling mode of the current picture block and the reference pixel. When position information of the prediction sample satisfies a sampling requirement according to a color sampling ratio associated with the color sampling mode, the prediction sample includes a chroma prediction sample that is obtained based on the reference pixel. Prediction values of the current picture block are obtained according to the prediction sample of the current pixel.