Video Decoder Intra-Prediction Mode Subset Selection
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Solution Overview
Problem
Conventional video coding technologies require decoders to consider all possible intra-prediction modes for each block of a video, expending computational resources and causing unnecessary latency in regenerating images.
Innovation Solution
Deriving intra-prediction modes from a subset of candidates based on cost calculations, using a most probable mode list to determine a final predictor for the current video block, rather than explicitly signaling all available modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all possible intra-prediction modes are explicitly signaled and considered for each video block, then the accuracy of prediction is improved, but the computational burden and latency increase significantly
Solution Approach 1:
The patent segments the full set of intra-prediction modes into a subset of most probable modes (MPMs) that are most likely to be used for a given video block. Instead of evaluating all possible modes, the decoder only needs to consider this segmented subset, significantly reducing computational complexity while maintaining prediction accuracy for the majority of cases.
Solution Approach 2:
The patent applies partial action by deriving only the necessary subset of intra-prediction modes rather than all possible modes. The MPM list contains a limited number of candidate modes (e.g., 6 modes) that are derived based on neighboring block information, providing sufficient prediction accuracy without the excessive computational cost of evaluating all modes.
2Adaptability or versatility
If all possible intra-prediction modes are explicitly signaled and considered for each video block, then the completeness of mode selection is improved, but the processing time and latency increase
Solution Approach 1:
The patent performs preliminary action by pre-deriving the most probable mode list at the decoder side before actual decoding. The MPM list is constructed using information from neighboring blocks that are already decoded, allowing the decoder to prepare a focused set of candidate modes in advance, thus reducing the time needed during the actual decoding process.
Solution Approach 2:
The patent extracts only the relevant subset of intra-prediction modes that are most likely to apply to the current video block, based on the characteristics of neighboring blocks. This extraction of essential modes from the full set eliminates unnecessary computational steps while preserving the adaptability needed for accurate prediction.
3Productivity
If a reduced set of candidate intra-prediction modes is used, then the computational efficiency is improved, but the risk of selecting suboptimal modes increases
Solution Approach 1:
The patent incorporates feedback mechanisms where the decoder uses information from already decoded neighboring blocks to inform the selection of MPMs for the current block. This feedback loop allows the reduced mode set to be adaptively constructed based on actual video content characteristics, ensuring that the most relevant modes are included while maintaining coding efficiency.
Solution Approach 2:
The patent changes the parameter of mode selection by using derived MPM lists that adapt to different video content characteristics. The composition of the MPM list varies based on neighboring block modes and other contextual parameters, allowing the system to maintain high reliability across different video scenarios while using a reduced mode set.
Data Source
AI summary
Aspects of the present disclosure provide techniques for derive one or more intra prediction modes (IPMs) from a subset of IPM candidates in order to determine a predictor to use for decoding a block of an image. In some aspects, the subset of IPM candidates may include IPMs that are less than the number of IPMs in a full set of all available IPM candidates (e.g., 67 IPMs in VVC or 35 in HEVC). In some aspects, the subset of IPM candidates may be based on a most probable mode (MPM) list that can be used to determine or signal an IPM based on IPMs previously used in decoding other blocks.