MDLM Chroma Mode Encoding with Independent CABAC Contexts
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Solution Overview
Problem
Existing video data encoding and decoding systems, such as High Efficiency Video Coding (HEVC), face inefficiencies in encoding and decoding data items related to multi-direction linear model (MDLM) chroma mode due to the use of a common context adaptive binary arithmetic coding (CABAC) context, which can lead to suboptimal compression efficiency.
Innovation Solution
The system employs a selective encoding and decoding approach using either context adaptive binary arithmetic coding (CABAC) or bypass encoding for data items indicating whether a multi-direction linear model (MDLM) chroma mode applies and its processing direction, allowing these items to be encoded and decoded independently, using separate contexts or fixed probability models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common CABAC context is used for encoding MDLM chroma mode data items, then the encoding process is simple, but compression efficiency deteriorates
Solution Approach 1:
The patent divides the encoding process into separate contexts: a first CABAC context for encoding the MDLM chroma mode flag and a second CABAC context for encoding the processing direction flag. This segmentation allows each context to be optimized independently for its specific data characteristics, improving compression efficiency while maintaining manageable complexity through structured separation of encoding operations.
2Loss of energy
If independent encoding contexts are used for MDLM chroma mode data items, then compression efficiency improves, but encoding complexity increases
Solution Approach 1:
The patent applies different encoding strategies to different data items based on their local characteristics: the MDLM chroma mode flag uses a first CABAC context optimized for mode indication, while the processing direction flag uses a second CABAC context optimized for direction information. This local quality approach allows each context to be tailored to its specific data properties, improving overall compression efficiency while keeping the complexity increase manageable through clear contextual separation.
3Loss of energy
If CABAC encoding is used for MDLM chroma mode data, then compression ratio improves, but processing time increases
Solution Approach 1:
The patent employs dynamic context adaptation where the CABAC contexts are updated based on previously encoded data statistics. The first CABAC context adapts to the distribution of MDLM chroma mode flags, while the second CABAC context adapts to processing direction patterns. This dynamic adaptation allows the system to achieve high compression ratios by leveraging statistical dependencies in the data while managing processing time through efficient context updates rather than requiring complex real-time analysis.
Data Source
AI summary
Image data encoding apparatus comprises an entropy encoder configured to selectively encode data items representing image data by an encoding system selected from a context adaptive binary arithmetic coding (CABAC), encoding system and a bypass encoding system; in which the data items include (i) a first data item indicating whether a multi-direction linear model (MDLM) chroma mode applies to a current image region; and (ii) a second data item indicating a processing direction for operation of the MDLM chroma mode; in which the entropy encoder is configured to encode instances of the first data item and to encode instances of the second data item independently of the encoding of instances of the first data item.