Modified MDCS for Non-Square Block Coding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing High-Efficiency Video Coding (HEVC) standard's Intra prediction mode-dependent coefficient scanning (MDCS) design is tailored for square blocks, leading to performance degradation when applied to non-square chroma blocks, particularly in 4:2:2 color subsampling patterns.
Innovation Solution
A modified MDCS is developed for non-square blocks by dividing Intra modes into multiple groups and adjusting the scanning patterns based on the angle spanned by mapped Intra modes, applying horizontal, vertical, or diagonal coefficient scanning depending on the group membership of the non-square block's Intra mode, thereby aligning with the original scanning patterns of square blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MDCS designed for square blocks is applied to non-square chroma blocks, then the device complexity remains simple, but the coding performance degrades
Solution Approach 1:
The patent modifies the MDCS by changing the grouping parameters of Intra modes based on the block shape. For non-square blocks, the angular range for vertical scanning is adjusted from modes 6-14 to modes 6-10, and horizontal scanning from modes 22-30 to modes 26-30. This parameter adaptation resolves the contradiction by tailoring the scanning pattern to the specific geometry of non-square chroma blocks, thereby improving coding performance without requiring a complete redesign of the MDCS framework.
Solution Approach 2:
The patent segments the Intra prediction modes into different groups based on the block shape (square vs. non-square). By dividing the mode range into distinct segments with different scanning patterns, the solution achieves better performance for each block type while maintaining a manageable level of overall system complexity. The segmentation allows the decoder to select appropriate scanning patterns based on simple block size detection.
2Reliability
If Intra modes are divided into multiple groups with different scanning patterns, then the coding performance for non-square blocks improves, but the ease of operation increases due to more complex mode grouping logic
Solution Approach 1:
The patent changes the angular range parameters for mode grouping specifically for non-square blocks. By adjusting the mode number ranges (e.g., vertical scanning modes 6-10 instead of 6-14), the solution maintains clear, rule-based grouping logic that is easy to implement. The decoder simply compares the current mode number against the adjusted ranges to determine the scanning pattern, preserving operational simplicity despite the performance improvement.
3Loss of information
If the scanning patterns are adjusted to match square block patterns, then the loss of information is reduced, but the adaptability to different block shapes decreases
Solution Approach 1:
The patent introduces dynamic adaptability by making the MDCS configuration dependent on the block shape. The system automatically adjusts the mode grouping and scanning pattern selection based on whether the block is square or non-square. This dynamic behavior allows the same MDCS framework to adapt to different block shapes while maintaining optimal scanning patterns for each case, thereby reducing information loss without sacrificing versatility.
Solution Approach 2:
The patent changes the scanning pattern parameters dynamically based on block geometry. For non-square chroma blocks, the angular ranges for vertical and horizontal scanning are modified to better match the block orientation. This parameter adaptation ensures that the scanning patterns align with the dominant frequency directions specific to each block shape, reducing information loss while maintaining high adaptability across different block types.
Data Source
AI summary
In a method and apparatus for predictive Intra coding of a non-square block using modified mode-dependent coefficient scanning (MDCS), the modified MDCS is derived from the MDCS that is designed for a square block. The mapped Intra modes for the non-square block are derived by mapping the Intra modes for the square block to the mapped Intra modes for the non-square block. The mapped Intra modes are divided into multiple groups including a first modified angular group and a second modified angular group. The modified MDCS modifies the number of the mapped Intra modes in the first modified angular group or the second modified angular group by comparing an angle spanned by the mapped Intra modes in the first modified angular group or the second modified angular group with the angle spanned by the corresponding Intra modes of the conventional MDCS.