Entropy Coding Context Initialization Across Temporal Sublayers
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Solution Overview
Problem
The existing video coding systems, particularly in versatile video coding (VVC), face challenges in efficiently initializing context states for entropy coding, leading to synchronization issues and reduced performance when handling multiple temporal sublayers and layers.
Innovation Solution
Implementing a method and apparatus for context initialization in entropy coding that utilizes separate context state buffers for different temporal sublayers and layers, allowing the use of stored context states with lower IDs or QPs for initialization, and dynamically managing buffer sizes and sharing among slice types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate context state buffers are used for different temporal sublayers, then synchronization accuracy is improved, but device complexity increases
Solution Approach 1:
The patent divides the context state management into separate buffers for different temporal sublayers (TL0 buffer and TL1 buffer). Each buffer stores context states specific to its temporal sublayer, preventing mixing and synchronization errors. This segmentation resolves the contradiction by organizing complexity into manageable, isolated units that improve synchronization accuracy.
Solution Approach 2:
The patent introduces a temporal sublayer dimension to the buffer structure, creating a two-dimensional organization (buffer × temporal sublayer). This allows context states from different temporal sublayers to be managed independently while maintaining overall system coherence, improving synchronization without requiring complex cross-layer management.
2Productivity
If context states from previous slices are reused for initialization, then coding efficiency is improved, but reliability decreases due to synchronization issues
Solution Approach 1:
The patent segments context state storage into temporally-specific buffers, allowing efficient reuse of context states within the same temporal sublayer while preventing unreliable cross-temporal-sublayer reuse. This maintains coding efficiency through context reuse while ensuring synchronization reliability by restricting reuse to appropriate temporal contexts.
Solution Approach 2:
The patent applies different context state management rules to different temporal sublayers. Context states from TL0 slices are reused for TL0 slice initialization, and context states from TL1 slices are reused for TL1 slice initialization. This local quality approach ensures that context reuse occurs only where it is reliable, maintaining both efficiency and synchronization accuracy.
3Device complexity
If context state buffers are shared among slice types, then device complexity is reduced, but adaptability decreases
Solution Approach 1:
The patent creates universal buffer structures (TL0 buffer and TL1 buffer) that can handle multiple slice types (B slices, P slices, etc.) within each temporal sublayer. Each buffer is designed to store context states from any slice type in its temporal sublayer, providing adaptability without requiring separate buffers for each slice type, thus maintaining low complexity.
Data Source
AI summary
A method and apparatus of context initialization for entropy coding. According to one method, previous context states derived from one or more previous slices for an arithmetic entropy coder are determined, where the previous context states are stored in multiple context state buffers and different context state buffers are used to store the previous context states for different temporal sublayers. Target context states are determined from the previous context states for the current slice in a current temporal sublayer indicated by a current temporal ID, wherein a target context state buffer storing the target context states is determined according to the current temporal ID. A current set of context states for the arithmetic entropy coder is initialized using the target context states. The input data is encoded or decoded using the arithmetic entropy coder after said initializing the current set of context states for the arithmetic entropy coder.