Entropy Coding Context Derivation for Intra Prediction Modes
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently encoding and decoding intra prediction modes due to the increasing number of possible directions, which affects coding efficiency and bitstream representation.
Innovation Solution
The proposed solution involves deriving contexts for set indices and mode indices for intra prediction modes based on information from the current block and neighboring blocks, allowing for efficient entropy coding and improved coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of intra prediction directions is increased to improve prediction accuracy, then the coding efficiency is improved, but the number of bits required for signaling increases
Solution Approach 1:
The patent divides the intra prediction mode selection into two stages: first selecting a mode set index from multiple mode sets, then selecting a mode index within the chosen set. This segmentation allows the system to handle a large number of prediction directions (65 modes) by breaking them into manageable groups, reducing the overall signaling bits while maintaining comprehensive coverage of prediction directions.
Solution Approach 2:
The patent introduces dynamic mode set selection where the available mode sets and their composition can change based on block characteristics, neighboring block modes, and prediction conditions. This dynamic adaptation allows the system to optimize the balance between prediction accuracy and signaling efficiency for different coding scenarios, rather than using a fixed mode selection approach.
2Productivity
If context-based entropy coding is used to reduce signaling bits, then the coding efficiency is improved, but the complexity of the encoding/decoding process increases
Solution Approach 1:
The patent performs preliminary derivation of context indices based on block information and neighboring block modes before the actual entropy coding process. By pre-calculating which contexts are relevant and organizing the mode sets in advance, the system reduces the computational complexity during the main encoding/decoding loop while still achieving the benefits of context-based adaptive coding.
Solution Approach 2:
The patent applies different context models and mode set compositions locally adapted to specific block characteristics and neighboring conditions. Each block can have its own optimized context selection based on local properties, allowing the system to achieve high coding efficiency without requiring a single complex universal model for all blocks.
Data Source
AI summary
Disclosed are methods, apparatus, and computer-readable storage medium for entropy/decoding contexts for intra prediction modes in video encoding/decoding. An example method includes receiving a video bitstream that includes a current block and deriving a first context used to entropy encode a set index based on coded information. The coded information comprises at least one of: information of the current block, and mode information of at least one neighboring block of the current block. The method further includes deriving a second context used to entropy encode a mode index for the current block based on the coded information, entropy decoding the set index according to the first context, and entropy decoding the mode index according to the second context. The method also includes determining the intra prediction mode for the current block based on the set index and the mode index.