Two-Step Cross-Component Prediction for Chroma Block Alignment
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Solution Overview
Problem
Current video coding standards, such as VVC, face inefficiencies in inter-component prediction, particularly for chroma components, due to downsampling and increased logic complexity, which affect the quality of decompressed video.
Innovation Solution
A two-step inter-component prediction method (TSICP) is introduced, where a temporary prediction block is generated from a collocated block of a different component using linear models, followed by downsampling or upsampling to align with the target block size, allowing for more flexible and efficient prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If downsampling is used for chroma component prediction, then bandwidth efficiency is improved, but video quality deteriorates
Solution Approach 1:
The patent divides the prediction process into two separate steps: first generating a prediction block from a collocated block of a different component, then downsampling that prediction block to match the target block size. This segmentation allows each step to be optimized independently, maintaining better quality than direct downsampling while still achieving bandwidth efficiency.
Solution Approach 2:
The patent introduces a temporary prediction block as an intermediary between the collocated block and the final chroma component. This intermediary structure allows for more flexible processing and better quality preservation during the downsampling operation, as the temporary block can be optimized before the final downsampling to the target block size.
2Manufacturing precision
If complex prediction modes are used, then video quality is improved, but processing complexity increases
Solution Approach 1:
The patent segments the complex prediction process into two simpler, sequential steps that are easier to implement and process. The first step generates a prediction block using a collocated block from a different component, and the second step downsamples this prediction block. This segmentation reduces the immediate complexity at each processing stage while maintaining overall quality.
3Speed
If block size mismatch is handled by direct downsampling, then processing speed is improved, but prediction accuracy deteriorates
Solution Approach 1:
The patent performs a preliminary action by generating a prediction block from a collocated block before downsampling. This preliminary prediction step ensures that the content is already optimized for the target component characteristics, so that subsequent downsampling to match block sizes maintains better accuracy compared to direct downsampling without the intermediate prediction step.
Data Source
AI summary
A method for video bitstream processing includes generating, using a first video block derived from a third video block of a first component and having a first size, a prediction block for a second video block of a video related to a second component, where the first component is different from the second component, and where the second video block has a second size that is different from the first size. The method also includes performing, using the prediction block, a conversion between the second video block and a bitstream representation of the video according to a two-step cross-component prediction mode (TSCPM).