Template Based Intra Mode Derivation With ISP Mode
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Solution Overview
Problem
Existing video encoding and decoding technologies face challenges in achieving high coding efficiency for intra prediction, particularly in deducing the intra sub-partitioning (ISP) mode of a coding block from surrounding reconstructed pixels.
Innovation Solution
The method involves partitioning templates of neighboring samples around a current video block, determining possible intra prediction modes, and deducing the intra sub-block partition direction and mode for encoding or decoding the current block without explicit signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If explicit signaling is used for intra sub-partitioning (ISP) mode in video encoding, then the decoder can accurately reconstruct the current block, but the signaling overhead increases reducing coding efficiency
Solution Approach 1:
The encoder derives the ISP mode and partition direction from the template pixels, and the decoder performs the same derivation process independently. Both sides use the same template-based derivation algorithm to determine the ISP mode without requiring explicit signaling, making the system self-sufficient and eliminating the need for additional bitrate allocation for mode information
Solution Approach 2:
The decoder copies the derivation process from the encoder by using the same template pixels and algorithm to determine the ISP mode and partition direction. This ensures both encoder and decoder arrive at the same conclusion without requiring the mode information to be transmitted in the bitstream
2Productivity
If template-based intra mode derivation (TIMD) is extended to include ISP mode deduction, then coding efficiency is improved, but the complexity of the encoding and decoding process increases
Solution Approach 1:
The template-based derivation mechanism serves multiple functions: it determines both the intra prediction mode and the ISP partition direction using the same template pixels and algorithm. This multi-functionality improves coding efficiency by jointly optimizing both parameters while avoiding the need for separate derivation processes
Solution Approach 2:
The template pixels are constructed in advance from the reconstructed neighboring samples before the ISP mode and partition direction are derived. This preliminary preparation of template data simplifies the subsequent derivation process and reduces the computational complexity during the actual encoding/decoding operations
3Measurement precision
If the intra sub-block partition direction is explicitly signaled in the bitstream, then the decoder can accurately reconstruct the current block, but the bitrate consumption increases
Solution Approach 1:
The partition direction is determined by the decoder through template-based derivation using the same algorithm as the encoder, making the system self-sufficient and eliminating the need to transmit partition direction information in the bitstream, thereby reducing bitrate consumption
Solution Approach 2:
The decoder copies the encoder's partition direction decision by performing the same template-based derivation process, ensuring both sides arrive at the identical partition direction without requiring explicit signaling of this parameter
Data Source
AI summary
Template based derivation of intra sub-partitioning (ISP) mode is used to improve coding efficiency of intra predicted coded video blocks. The template is formed from surrounding reconstructed top and left samples. In one embodiment, ISP is performed independently from template based intra mode derivation (TIMD). The derivation of an intra sub-block partition mode is determined from template pixels using a current prediction mode for either an upper or left template. In another embodiment, ISP and TIMD are combined. In a further embodiment, a flag is signaled to communicate template based intra mode derivation and intra sub-block partition usage.