Adaptive De-blocking Filter Parameter Control
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Solution Overview
Problem
Current de-blocking filtering methods in video coding standards like HEVC do not consistently achieve optimal subjective and objective performance across different video sequences, as they use fixed parameters regardless of local image characteristics.
Innovation Solution
An adaptive de-blocking filter method that determines and signals specific parameters such as thresholds and clipping boundaries for each picture, slice, or coding unit, allowing for customized filtering based on local characteristics, and uses predictive coding and training processes to optimize these parameters for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed parameters are used for de-blocking filter in HEVC, then device complexity is reduced, but filtering performance is insufficient for different video sequences
Solution Approach 1:
The patent implements dynamic parameter adaptation for de-blocking filters by allowing different threshold and clipping boundary parameters to be selected based on local characteristics of video blocks. The filter transitions from a static fixed-parameter approach to a dynamic adaptive approach where parameters are determined on-demand based on boundary strength and local block characteristics, resolving the contradiction between maintaining simplicity and achieving performance across diverse video content.
Solution Approach 2:
The patent changes the parameter set of the de-blocking filter adaptively by introducing multiple threshold and clipping boundary parameter options. Instead of using a single fixed parameter set, the system selects from multiple parameter configurations based on local video characteristics, enabling the filter to optimize performance for different video sequences while maintaining a manageable complexity through predefined parameter sets.
2Reliability
If adaptive parameters are determined for each picture or coding unit, then filtering performance is improved, but signaling overhead and complexity increase
Solution Approach 1:
The patent applies local quality by determining de-blocking filter parameters specifically for each picture, slice, or coding unit based on its local characteristics. This allows each region to have optimized filtering parameters tailored to its specific content properties, improving subjective and objective performance. The local adaptation is achieved by calculating boundary strength and other metrics specific to each coding unit's boundaries, ensuring parameters match local video characteristics rather than applying a global fixed parameter set.
Solution Approach 2:
The patent performs preliminary determination of filter parameters before the actual de-blocking filtering operation. By pre-calculating boundary strength, selecting appropriate threshold and clipping boundary parameters, and preparing the filter configuration in advance for each coding unit, the system optimizes performance without adding excessive signaling overhead during the main decoding process. This preliminary action allows the adaptive parameters to be ready when needed, improving performance while managing complexity.
3Productivity
If fixed de-blocking filter parameters are used, then processing speed is maintained, but blocking artifacts remain visible in reconstructed blocks
Solution Approach 1:
The patent changes filter parameters adaptively based on local block characteristics to reduce visible blocking artifacts. By adjusting threshold and clipping boundary parameters according to boundary strength and local video content properties, the filter effectively reduces blocking artifacts in reconstructed blocks. This parameter adaptation maintains processing speed by using predefined parameter sets and efficient selection logic rather than complex iterative optimization, resolving the contradiction between artifact reduction and processing efficiency.
Data Source
AI summary
A method and apparatus for adaptive de-blocking filter are disclosed. One or more parameters associated with a de-blocking filter are determined. De-blocking filter using the derived parameters are then applied to reconstructed blocks. Each set of parameters is used for each picture, slice, coding tree unit (CTU) or CU (coding unit). The parameters can be signalled in VPS (video parameter set), SPS (sequence parameter set), PPS (picture parameter set), slice header, CTU (coding tree unit) or CU (coding unit) of the video bitstream. The parameters correspond to one or more values used as thresholds, clipping boundaries, or both the thresholds and clipping boundaries for the de-blocking filter. In one embodiment, the parameters for the current picture are determined using a training process using a current coded picture a previous coded picture as training data.