ISP Chroma Transform Block Sizing Across Chroma Formats
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Solution Overview
Problem
Existing video coding technologies face challenges in achieving efficient compression of video data without sacrificing picture quality, particularly in determining the size of chroma transform blocks for Intra Sub-Partitions (ISP) coding mode.
Innovation Solution
A method and apparatus for determining the size of chroma transform blocks based on chroma format information and conditions, including the use of a single tree partitioning and ISP for luma coding blocks, with encoding and decoding processes that include bitstream information to indicate block splitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Intra Sub-Partitions (ISP) coding mode is used for luma block splitting, then prediction accuracy is improved, but chroma transform block size determination becomes complex and inconsistent
Solution Approach 1:
The patent changes the parameter for determining chroma transform block size from complex conditional logic to a direct mapping based on luma block size. When ISP mode is used, the chroma transform block size is determined by simple scaling factors (e.g., width_scale and height_scale) applied to the luma block dimensions, converting a complex determination problem into a straightforward parameter transformation.
Solution Approach 2:
The patent segments the chroma transform block size determination into distinct cases based on luma block size categories. By dividing the problem into discrete size ranges and applying specific scaling rules to each segment, the patent simplifies the overall determination process while maintaining accuracy for different block dimensions.
2Quantity of substance
If video data is compressed to reduce data size for transmission and storage, then bandwidth and memory requirements are reduced, but picture quality may be sacrificed
Solution Approach 1:
The patent applies local quality by allowing different chroma transform block sizes for different regions of the video data. Instead of using a uniform block size for all chroma blocks, the patent dynamically determines chroma block sizes based on the corresponding luma block sizes and ISP mode, enabling finer-grained compression that adapts to local picture characteristics and maintains quality where needed.
Solution Approach 2:
The patent introduces dynamics by making chroma transform block sizes adaptive rather than fixed. The chroma block size changes dynamically based on the luma block size and ISP mode settings, allowing the compression system to optimize the balance between compression ratio and picture quality for different video content and regions.
Data Source
AI summary
Apparatuses and methods for Intra Sub-Partitions (ISP) are provided. The method includes: obtaining information of ISP, and determining a size of a chroma transform block (TB) of the coding unit based on SubWidthC and SubHeightC when at least a first condition is fulfilled. The first condition includes the information of ISP indicates that ISP is used for splitting the luma coding block. Sub WidthC and SubHeightC are variables depending on chroma format information. The chroma format information indicates a chroma format of a picture the coding unit belongs to. The method can apply to all chroma format. The chroma format includes at least one of: 4:2:0, or 4:2:2, or 4:4:4. An accurate and versatile way to determine the size of the chroma transform block for the ISP is achieved.