Multiple Line Intra Prediction Mode Selection for Video Compression
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Solution Overview
Problem
Current video coding technologies, such as HEVC, face limitations in intra prediction schemes, particularly with multiple reference lines, where the first reference line is often selected, and the potential coding gain of multiple line intra prediction with chroma components is not fully exploited, leading to suboptimal performance in predicting pixel values.
Innovation Solution
The proposed method includes a processor-based system that performs intra prediction among multiple reference lines, sets intra prediction modes for a zero reference line and nearest non-zero reference lines, and determines the most probable modes based on the reference line index, excluding planar and DC modes from the most probable mode list, to optimize pixel prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple reference lines are used for intra prediction, then prediction accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the intra prediction process by separating mode selection into different stages: first determining a reference line index, then selecting modes from an MPM list specific to that reference line. This segmentation allows the system to handle multiple reference lines systematically, improving prediction accuracy while managing complexity through structured processing
Solution Approach 2:
The patent applies preliminary action by pre-defining Most Probable Mode (MPM) lists for each reference line index before actual prediction. The encoder and decoder both prepare these MPM lists in advance based on neighboring block modes, so that when prediction is needed, the mode selection is already optimized. This preliminary preparation improves prediction accuracy without adding runtime complexity
2Productivity
If multiple line intra prediction is applied to chroma component, then coding gain is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by allowing different reference line configurations for different color components. Specifically, chroma blocks can use multiple reference lines with index > 0 when beneficial, while luma blocks follow traditional single-reference-line prediction. This localized application of multi-line prediction to only where it provides coding gain (chroma components) avoids unnecessary complexity in luma processing
3Measurement precision
If reference line index is signaled for each block, then prediction accuracy is improved, but bit rate increases
Solution Approach 1:
The patent applies partial action by selectively signaling reference line indices only when necessary. Instead of always signaling the reference line index for every block, the system signals it only when the optimal reference line is not the default (index 0). This partial signaling approach maintains prediction accuracy by providing full information when needed while reducing bit rate by omitting redundant signals when the default reference line suffices
Data Source
AI summary
There is includes a method and apparatus comprising computer code configured to cause a hardware processor or processors to perform intra prediction among a plurality of reference lines, to set a plurality of intra prediction modes for a zero reference line nearest to a current block of the intra prediction among non-zero reference lines, and to set one or more most probable modes for one of the non-zero reference lines.