Intra Prediction Mode Coding with Dynamic Neighbor-Based MPM Lists
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Solution Overview
Problem
Existing video coding technologies face challenges in reducing processor load during intra prediction processing, particularly in efficiently selecting entries for the Most Probable Mode (MPM) list, which affects the efficiency of intra prediction mode coding.
Innovation Solution
A method for generating a Most Probable Mode (MPM) list by obtaining intra prediction modes from neighboring blocks and constructing a list with specific entries based on conditions related to the angular modes of these neighboring blocks, thereby enhancing coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional MPM list with limited entries is used for intra prediction mode coding, then the device complexity is reduced, but the coding efficiency deteriorates due to insufficient inclusion of commonly used modes
Solution Approach 1:
The MPM list is made dynamic by constructing different list configurations based on the angular modes of neighboring blocks. When left and above neighbor blocks share the same angular mode, a specialized 5-entry list is used; otherwise, a different configuration is applied. This dynamic adaptation optimizes coding efficiency for different block scenarios without requiring a permanently large list structure.
Solution Approach 2:
The invention changes the parameters of the MPM list by selectively including specific angular modes based on neighbor block characteristics. The list includes modes {ang, 2+((ang+61)d), 2+((ang−1)d), 2+((ang+60)d), 2+((ang) d)} when neighbors share the same angular mode, effectively tailoring the mode selection to local image characteristics and reducing the need to code actual mode values.
2Productivity
If more intra prediction modes are included in the MPM list, then the coding efficiency improves, but the processor load increases due to more complex mode selection and list management
Solution Approach 1:
The MPM list construction is segmented into different cases based on the angular modes of neighboring blocks. The encoder first checks whether left and above neighbors share the same angular mode, then constructs the appropriate 5-entry list accordingly. This segmentation allows efficient processing by avoiding unnecessary comparisons and directly selecting the appropriate list configuration.
Solution Approach 2:
The MPM list is constructed in advance before actual intra prediction mode coding. By pre-determining the list of most probable modes based on neighbor block characteristics, the encoder prepares the optimal mode set beforehand, avoiding the need for exhaustive mode evaluation during the actual coding process and thereby reducing processor load.
3Loss of information
If the MPM list uses actual mode values, then the coding precision is maintained, but the bit rate increases due to more bits required for mode representation
Solution Approach 1:
Instead of coding actual mode values directly, the invention uses a copied reference approach where the MPM list stores pre-selected angular modes derived from neighboring blocks. The current block's prediction mode is selected from this copied list of probable modes, allowing efficient representation through index coding rather than full mode value coding, thereby reducing bit rate while maintaining coding precision.
Data Source
AI summary
It is provided a method of prediction coding of a current block, comprising: obtaining an intra prediction mode of a left neighbor block of the current block and an intra prediction mode of an above neighbor block of the current block; constructing a Most Probable Mode (MPM) list of intra prediction modes for the current block, the MPM list comprising at least 5 entries of intra prediction modes as follows: {ang, 2+((ang+61)%64), 2+((ang−1)%64), 2+((ang+60)%64), 2+((ang) %64)} when at least a first condition is fulfilled, where ang represents the intra prediction mode of the left neighbor block or the intra prediction mode of the above neighbor block.