Adaptive Loop Filtering With Bit-Depth Clipping for Video Coding
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Solution Overview
Problem
Existing video coding technologies lack an efficient mechanism for encoding and decoding chroma and luma components while maintaining image quality, particularly in adaptive loop filtering processes.
Innovation Solution
Implementing a bit depth-based clipping operation in adaptive loop filtering for chroma and luma samples, using a predefined clipping boundary value formula or table to determine clipping boundaries for each sample, which is stored in both the encoder and decoder, and applying this operation to improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adaptive loop filtering is applied to chroma and luma components, then image quality is improved, but coding complexity increases
Solution Approach 1:
The patent applies bit depth-based clipping operations that adapt the filtering parameters according to the bit depth of the video signal. By dynamically adjusting clipping boundaries based on bit depth parameters, the filter achieves better image quality across different resolutions while maintaining consistent computational complexity.
Solution Approach 2:
The patent selectively applies clipping operations only when beneficial, using conditions based on bit depth and filter coefficient values. This partial application approach avoids unnecessary computations in cases where full clipping would not improve image quality, thus reducing overall coding complexity while maintaining image quality where needed.
2Productivity
If bit depth-based clipping operation is implemented, then coding efficiency is improved, but computational overhead increases
Solution Approach 1:
The patent pre-calculates clipping boundaries based on bit depth parameters and stores them in lookup tables. During actual filtering operations, the pre-computed boundaries are directly retrieved and applied, eliminating the need for real-time complex calculations and reducing computational overhead while maintaining coding efficiency.
Solution Approach 2:
The patent introduces clipping boundary values as intermediary parameters that mediate between the filter coefficients and the final filtered output. These intermediaries simplify the filtering computation by constraining the range of values that need to be processed, thereby reducing computational overhead while preserving coding efficiency.
Data Source
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AI summary
The present invention is directed to a method for encoding video data, the comprising the steps of obtaining a plurality of coding tree units divided from a video frame; for a coding tree unit in the plurality of coding tree units, obtaining a plurality of image samples, each image sample corresponding to one of a luma sample and a chroma sample; for each of the plurality of image samples, filtering a respective image sample using an adaptive loop filter having a filter length L and a set of filter coefficients, further including: identifying a set of related image samples of the respective image sample; for each of the set of related image samples, identifying a respective clip value index and a corresponding filter coefficient; clipping a difference between each of the set of related image samples and the respective image sample based on the respective clip value index, wherein the respective clip value index corresponds to a respective clipping boundary value equal to 2 to a power of a respective clipping number, and all respective clipping numbers corresponding to each respective clipping value index are integers; and modifying the respective image sample with the clipped difference between each of the set of related image samples and the respective image sample based on the corresponding filter coefficient.