Decoder Side Intra Mode Derivation for Video Coding
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Solution Overview
Problem
Current video coding technologies face challenges in efficiently deriving intra prediction modes for video blocks, leading to suboptimal compression ratios and increased bandwidth requirements due to the limitations in intra mode derivation methods.
Innovation Solution
The proposed solution involves decoder-side intra mode derivation (DIMD) and template-based intra mode derivation (TIMD) methods, which allow for the derivation of intra prediction modes based on neighboring blocks, using context models and weighted summation of predictors to improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional intra prediction methods are used, then device complexity is reduced, but compression ratio deteriorates
Solution Approach 1:
The decoder autonomously derives intra prediction modes for neighboring blocks without requiring explicit mode information from the encoder. The decoder uses its own reconstructed samples to generate prediction modes, eliminating the need for complex encoder-side mode selection and signaling while maintaining good compression performance.
Solution Approach 2:
The decoder performs intra mode derivation for neighboring blocks in advance, before decoding the current block. This preliminary derivation of prediction modes from already-decoded neighboring blocks enables efficient prediction for the current block without increasing overall system complexity.
2Loss of information
If more intra prediction modes are derived, then compression ratio is improved, but bandwidth requirements increase
Solution Approach 1:
The decoder copies prediction modes from neighboring blocks that have already been decoded and reconstructed. Instead of transmitting mode information for each block, the system copies and reuses prediction modes from spatially adjacent blocks, reducing bandwidth requirements while maintaining compression efficiency.
3Measurement precision
If intra mode derivation is performed at the encoder, then prediction accuracy is improved, but device complexity increases
Solution Approach 1:
Instead of having the encoder perform complex intra mode derivation and signal the modes to the decoder, the invention inverts the process by having the decoder perform the mode derivation itself. This shifts the computational complexity from the encoder to the decoder, where it can be performed using already-available reconstructed samples.
Data Source
AI summary
In a method of video decoding, coded information of a current block is received. First information associated with the current block in the coded information is obtained. The first information indicates whether the current block is intra predicted based on decoder side intra mode derivation (DIMD). Second information associated with the current block in the coded information is obtained. The second information indicates whether the current block is partitioned based on an intra sub-partition (ISP) mode. A context model index is determined in response to one of (i) the first information indicating that the current block is intra predicted based on the DIMD, and (ii) the second information indicating that an above adjacent block or a left adjacent block of the current block is partitioned based on the ISP mode. The current block is decoded from the coded video stream based at least on the context model index.