Sampling Grid Alignment in Multi-Layer Video Coding
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Solution Overview
Problem
In multi-layer video coding, the misalignment of sampling grids between video layers can lead to reduced coding efficiency and visual artifacts, particularly when down-sampling and up-sampling processes are applied with different phase shifts, affecting motion vector prediction accuracy and overall video quality.
Innovation Solution
The proposed solution involves signaling sampling grid information to correct misalignments by aligning the sampling grids between video layers, using techniques such as adaptive filter training and poly-phase filters to ensure precise alignment, thereby improving the prediction and coding efficiency of the enhancement layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If down-sampling and up-sampling processes are applied with different phase shifts, then device complexity is reduced, but sampling grid misalignment occurs leading to reduced coding efficiency
Solution Approach 1:
The patent applies preliminary action by detecting the sampling grid misalignment between base layer and enhancement layer before the coding process. The system determines the relative sampling grid offset and applies correction in advance, ensuring that subsequent coding operations work with aligned grids, thereby maintaining coding efficiency without requiring complex real-time adjustments during encoding.
Solution Approach 2:
The patent employs parameter changes by modifying the sampling grid parameters (offset values) based on detected misalignment. The system adjusts the sampling grid position parameters to compensate for the phase shift differences introduced by down-sampling and up-sampling operations, thereby realigning the grids while maintaining the simplicity of the original processing pipeline.
2Productivity
If sampling grid misalignment is corrected using adaptive filter training and poly-phase filters, then coding efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by using the enhancement layer picture itself to train the adaptive filter. The system utilizes the available enhancement layer data to automatically determine the optimal filter coefficients that align the sampling grids, eliminating the need for external calibration or manual intervention. This self-training mechanism improves coding efficiency while keeping the system relatively simple by leveraging existing data resources.
3Measurement precision
If sampling grid information is signaled between video layers, then motion vector prediction accuracy is improved, but loss of information increases due to additional data transmission
Solution Approach 1:
The patent applies partial action by signaling only the necessary sampling grid offset information rather than complete grid parameters. The system transmits minimal offset values that are sufficient to correct the misalignment, avoiding the transmission of redundant data. This selective signaling approach maintains motion vector prediction accuracy while minimizing bitrate overhead.
4Object-affected harmful factors
If sampling grids are aligned between video layers, then visual artifacts are reduced, but processing time increases due to additional alignment operations
Solution Approach 1:
The patent applies preliminary action by performing sampling grid alignment detection and correction before the main video coding process. By establishing proper grid alignment in advance, the system eliminates visual artifacts that would otherwise appear in the decoded video, while the subsequent coding operations proceed efficiently without repeated alignment checks, thus minimizing overall processing time.
Data Source
AI summary
Sampling grid information may be determined for multi-layer video coding systems. The sampling grid information may be used to align the video layers of a coding system. Sampling grid correction may be performed based on the sampling grid information. The sampling grids may also be detected. In some embodiments, a sampling grid precision may also be detected and/or signaled.