MRL Intra Mode Selection Using Template Matching for Video Coding
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in intra prediction due to the use of less likely prediction directions requiring more bits, leading to suboptimal compression ratios.
Innovation Solution
Implementing a template matching based multiple reference line (MRL) intra prediction mode that determines a reference region by calculating cost values between template and reference regions, allowing for more efficient reconstruction of coding units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional intra prediction with fixed prediction directions is used, then the coding structure is simple, but less likely prediction directions require more bits leading to suboptimal compression ratios
Solution Approach 1:
The patent implements dynamic reference line selection where the decoder determines which reference line to use based on template matching cost calculations. Instead of using a fixed prediction direction, the system dynamically selects from multiple reference lines (first, second, third reference lines) by calculating costs between template blocks and reference blocks, then choosing the line with the minimum cost. This dynamic adaptation allows the system to optimize compression ratios for different content types while maintaining a relatively simple coding structure.
2Productivity
If template matching based MRL intra prediction mode is implemented, then compression ratios improve, but the number of bits required for signaling increases
Solution Approach 1:
The patent applies partial action by only signaling the reference line index when template matching based MRL intra prediction mode is actually used, rather than always signaling all reference line information. The system conditionally includes the reference line index in the bitstream based on a mode flag, thereby reducing unnecessary bitrate overhead while still enabling the compression benefits of template matching when applicable.
Solution Approach 2:
The patent changes the parameter representation by using a compact reference line index (taking values 0, 1, or 2) to indicate which reference line to use, rather than signaling full directional information. This parameter optimization reduces the number of bits required to signal the prediction mode while maintaining the ability to select from multiple reference lines, thus improving compression efficiency without excessive bitrate increase.
3Measurement precision
If multiple reference regions are evaluated with cost calculations, then prediction accuracy improves, but processing complexity increases
Solution Approach 1:
The patent segments the reference region evaluation into distinct, manageable steps: (1) identify multiple candidate reference lines, (2) extract template blocks from each reference line, (3) calculate costs between template blocks and current block, (4) select the reference line with minimum cost. This segmentation of the processing task makes the complexity more manageable and allows for potential optimizations in each individual step while maintaining overall prediction accuracy.
Solution Approach 2:
The patent performs preliminary actions by pre-identifying candidate reference lines and extracting template blocks before the actual cost calculation and selection process. By preparing the template blocks from multiple reference lines in advance, the system reduces the computational burden during the final selection phase, making the overall process more efficient while still evaluating multiple reference regions for accurate prediction.
Data Source
AI summary
In a method of decoding, coded information of a coding unit (CU), a template region, and a plurality of reference regions is received. The coded information includes a first syntax element indicating whether the CU is predicted based on a template matching based multiple reference line (MRL) intra prediction mode. In response to the first syntax element indicating that the CU is predicted based on the template matching based multiple reference line (MRL) intra prediction mode, a plurality of cost values is determined between (i) respective prediction samples of the template region based on samples in each of the plurality of reference regions, and (ii) reconstructed samples of the template region corresponding to the respective prediction samples. A reference region from the plurality of reference regions is determined based on the plurality of cost values. Samples of the CU are reconstructed based on the samples in the determined reference region.