Intra Reference Direction Estimation for HEVC Coding Efficiency
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Solution Overview
Problem
Conventional encoding devices using H.265/HEVC struggle to reduce the code amount in intra prediction for the angle prediction mode due to difficulties in estimating occurrence probabilities, leading to inefficient coded stream generation.
Innovation Solution
The encoding device estimates a prediction value for the reference direction in a block based on the selected reference direction from an adjacent block and performs arithmetic encoding on the difference between the binary signal and the prediction value, increasing the occurrence probability of the most significant bit to switch from bypass mode to context mode for arithmetic encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional H.265/HEVC encoding is used for intra prediction in angle prediction mode, then the encoding process is straightforward, but the code amount cannot be reduced efficiently due to difficulties in estimating occurrence probabilities
Solution Approach 1:
The patent applies preliminary action by estimating the occurrence probability of reference directions before actual encoding. The probability estimation unit calculates occurrence probabilities of reference directions for blocks based on neighboring block information in advance, allowing the arithmetic encoding unit to switch to context mode when probabilities exceed thresholds, thereby reducing code amount without increasing operational complexity during encoding
Solution Approach 2:
The patent changes the parameter of occurrence probability estimation by using neighboring block reference direction information to predict current block probabilities. This parameter change enables dynamic switching between bypass mode and context mode in arithmetic encoding, optimizing code amount reduction while maintaining manageable encoding complexity
2Productivity
If arithmetic encoding in context mode is used to reduce code amount, then coding efficiency improves, but the complexity of probability estimation increases
Solution Approach 1:
The patent applies local quality by selectively applying context mode only to blocks where occurrence probability estimation indicates benefit. The arithmetic encoding unit switches to context mode locally for specific blocks based on probability thresholds, rather than applying complex probability estimation universally, thus improving coding efficiency while controlling overall system complexity
Solution Approach 2:
The patent uses partial action by implementing probability estimation and context mode switching only when beneficial for code reduction. The system estimates probabilities and switches to context mode partially for blocks exceeding probability thresholds, avoiding full complexity application to all blocks, thereby balancing coding efficiency improvement with complexity management
Data Source
AI summary
An encoding device includes: a memory; and a processor coupled to the memory and configured to: estimate a prediction value in a reference direction that is selected when intra prediction in an angle prediction mode is performed in a block to be processed on the basis of a value indicating a reference direction selected when the intra prediction in the angle prediction mode has been performed in an adjacent block adjacent to the block to be processed; and binarize the value indicating the reference direction selected when the intra prediction in the angle prediction mode has been performed in the block to be processed and perform arithmetic encoding for a comparison result between a value of a most significant bit of a binary signal and the prediction value.