Partitioned Intra Coding for Video Compression Efficiency
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Solution Overview
Problem
Existing block-based codecs face challenges in achieving high coding efficiency for intra-prediction, as they struggle to balance signaling overhead and prediction accuracy, particularly in larger blocks where spatial prediction tends to be less accurate.
Innovation Solution
The proposed solution involves a decoder and encoder configuration that partitions a block into multiple partitions, allowing for sequential reconstruction using a predetermined partition order. This approach derives a predictor for each partition based on neighboring samples and corrects it using a prediction residual, enabling flexible partitioning dimensions and orders to optimize coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the block size is increased to reduce signaling overhead, then the signaling overhead is reduced, but the prediction accuracy deteriorates due to higher mean sample distance
Solution Approach 1:
The current block is divided into multiple sub-blocks, allowing independent intra-prediction mode selection for each sub-block. This segmentation enables finer-grained prediction that maintains accuracy while managing signaling overhead through context-based mode inheritance and default mode mechanisms.
Solution Approach 2:
Different intra-prediction modes are applied to different sub-blocks based on local characteristics. Each sub-block can have its own prediction mode selected from context-based candidates, allowing local optimization of prediction accuracy while the overall block structure manages signaling efficiency.
2Measurement precision
If more intra-prediction modes are added to improve prediction accuracy, then the prediction accuracy is improved, but the signaling overhead increases
Solution Approach 1:
The number and type of available intra-prediction modes are dynamically changed based on block characteristics such as size, shape, and neighboring block modes. This adaptive parameter selection allows the system to use more modes when needed for accuracy while using fewer modes when not necessary, optimizing the trade-off between prediction accuracy and signaling overhead.
Solution Approach 2:
Instead of signaling all available intra-prediction modes for every block, the system uses partial action by selecting only the most relevant modes from a context-based candidate list. This reduces signaling overhead while maintaining sufficient prediction accuracy through intelligent mode selection rather than exhaustive mode signaling.
3Measurement precision
If fine-grained partitioning is applied to improve prediction accuracy, then the prediction accuracy is improved, but the device complexity increases
Solution Approach 1:
The block is segmented into sub-blocks with a limited set of predefined partitioning patterns based on block size and shape. This segmentation enables fine-grained prediction while controlling complexity through standardized partitioning rules and context-based mode inheritance, avoiding the need for complex adaptive partitioning algorithms.
Solution Approach 2:
The partitioning structure and candidate mode lists are prepared in advance based on block characteristics before actual prediction mode selection. This preliminary action reduces runtime complexity by pre-organizing the search space and candidate modes, allowing faster mode selection while maintaining fine-grained prediction capability.
Data Source
AI summary
Block-based coding of a picture is done by providing an intra-prediction coding concept according to which a certain block of the picture is intra-prediction coded using a certain intra-coding mode by partitioning the predetermined block into partitions which are, for reconstruction purposes, sequentially subject to spatial prediction using the intra-prediction coding mode signaled for the certain block followed by correcting the thus obtained predictor using a prediction residual so that for preceding partitions a reconstruction of the samples is available to the decoder at the time of processing the next, then current, partition.