CABAC Context Pre-Initialization for Low-Latency Syntax Decoding
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Solution Overview
Problem
The complexity of CABAC decoding processes in H.264/AVC systems leads to significant latency due to the lengthy initialization and arithmetic decoding steps, which hampers the overall efficiency of the decoding system.
Innovation Solution
A CABAC decoding apparatus and method that includes an initialization module for pre-initializing context variables, a storage module for storing these variables, and an arithmetic decoding module that can directly retrieve them, reducing the need for real-time initialization during the decoding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CABAC technology is used for entropy encoding, then coding efficiency is improved by about 10% compared to CAVLC, but encoding/decoding calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-initializing context variables before macro-block level bit stream processing begins. The initialization module pre-calculates and stores context variables in advance, so that during actual arithmetic decoding, these pre-initialized variables can be directly retrieved without waiting for initialization, thus reducing decoding latency while maintaining CABAC's high coding efficiency
2Reliability
If complete initialization and arithmetic decoding steps are performed during CABAC decoding, then decoding accuracy is ensured, but decoding time becomes relatively long, affecting system efficiency
Solution Approach 1:
The patent performs the initialization action in advance by pre-initializing context variables before the macro-block level bit stream is ready. This preliminary action separates the initialization phase from the decoding phase, allowing the arithmetic decoding module to directly use pre-initialized variables during decoding, thus ensuring decoding accuracy while significantly reducing the time required during actual decoding operations
Solution Approach 2:
The patent segments the decoding process into distinct phases: an initialization phase where context variables are pre-calculated and stored, and a decoding phase where arithmetic decoding is performed using the pre-initialized variables. This segmentation allows each phase to be optimized independently, ensuring accuracy in the decoding phase while minimizing its time consumption
Data Source
AI summary
A decoding method is adapted to be implemented using a Context-based Adaptive Binary Arithmetic Coding (CABAC) decoding apparatus, and includes: initializing a plurality of context variables; storing the context variables; performing arithmetic decoding of a syntax element according to the context variables so as to output a decoded syntax element and an update signal; and updating at least one of the context variables according to the update signal. At least one of the context variables is pre-initialized in the initializing step before a bit stream ready.