Block Coefficient Coding Using Context Flags and Size-Based Mode Selection
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Solution Overview
Problem
Existing video coding technologies face inefficiencies and increased overhead when handling high bit depth, high quality, and high bitrate video, particularly due to the complexity of context-based adaptive binary arithmetic coding (CABAC) and the dependency on context models, which affect coding speed and throughput.
Innovation Solution
A method for encoding and decoding that determines a context mode flag and initial quantity parameter based on block height and width parameters, using either context or bypass modes to encode/decode coefficients, optimizing the coding process to reduce complexity and improve throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If context-based adaptive binary arithmetic coding (CABAC) is used for high bit depth, high quality, and high bitrate video, then coding quality is improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent segments the coefficient coding process into two distinct modes: context mode and bypass mode. The context mode flag divides coefficients into those requiring context-based adaptive binary arithmetic coding (for quality-critical regions) and those using simpler encoding (for less critical regions). This segmentation allows the system to apply complex CABAC only where necessary, reducing overall processing overhead while maintaining coding quality.
Solution Approach 2:
The patent applies different coding strategies to different regions of the coefficient block based on local characteristics. By using the context mode flag to identify specific coefficients that benefit from CABAC, the system applies high-quality context-based encoding locally to important coefficients while using simpler bypass mode encoding for others, optimizing the balance between quality and complexity.
2Measurement precision
If context mode is used for all coefficients, then coding precision is improved, but coding speed decreases
Solution Approach 1:
The patent applies context mode encoding selectively to only those coefficients that require it, rather than applying it to all coefficients. The context mode flag identifies which coefficients should receive the more precise but slower context-based encoding, while other coefficients use the faster bypass mode. This partial application of the complex encoding method maintains coding precision where needed while preserving overall coding speed.
3Adaptability or versatility
If context mode flag is always decoded, then adaptability is improved, but loss of time increases
Solution Approach 1:
The patent extracts the context mode flag as a separate, optional element in the bitstream that is only processed when necessary. Instead of always decoding context mode information for every coefficient, the system only decodes and processes the context mode flag for coefficients that actually require context-based encoding. This extraction approach maintains coding adaptability while significantly reducing the time lost to unnecessary decoding operations.
Data Source
AI summary
Embodiments of the disclosure provide a coding method, an encoder, and a decoder. The decoder decodes a bitstream to determine a context mode flag of a current block, determines a height parameter and a width parameter of the current block, determines an initial value of a quantity parameter as a first quantity value based on a value of the context mode flag being a first value, determines the initial value of the quantity parameter according to the height parameter and the width parameter based on the value of the context mode flag being a second value, and determines coefficients of the current block using at least one of a context mode or a bypass mode according to the initial value of the quantity parameter.