Transform Domain Filter with Look-Up Table for Video Coding
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Solution Overview
Problem
Current video coding technologies face challenges in maintaining video quality while reducing bandwidth requirements, with existing filters requiring complex rate-distortion optimization and large numbers of weighting coefficients, leading to inefficiencies in processing and increased complexity.
Innovation Solution
The implementation of a transform domain filter, such as the Hadamard transform domain filter, which determines filter parameters from the frame itself, reducing the need for signaling filter parameters and allowing for efficient filtering with lower complexity by using a look-up table (LUT) for gain coefficients based on spectrum components and filtering parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive loop filter with weighting coefficients is used to improve video quality, then filtering effectiveness is improved, but device complexity and processing complexity increase due to complex rate-distortion optimization and large numbers of weighting coefficients
Solution Approach 1:
The patent extracts only the essential filtering parameters needed for quality improvement while removing unnecessary complexity. Instead of transmitting full weighting coefficients, the invention transmits simplified parameters that can be used to generate filter coefficients at the decoder side, reducing both transmission overhead and processing complexity while maintaining filtering effectiveness
Solution Approach 2:
The filtering process is segmented into parameter transmission and coefficient generation stages. The encoder transmits a limited set of parameters, and the decoder segments the reconstruction process by using these parameters to generate the actual filter coefficients needed for reconstruction, separating the complex optimization from the filtering operation
2Reliability
If more weighting coefficients are transmitted to improve filtering accuracy, then video quality is improved, but bandwidth requirements increase
Solution Approach 1:
Instead of copying and transmitting all necessary weighting coefficients, the invention transmits a compact set of parameters that enable the decoder to reconstruct the filter coefficients locally. This parameter-based copying approach maintains filtering accuracy while dramatically reducing the quantity of data that must be transmitted
Solution Approach 2:
The encoder performs preliminary parameter selection and optimization, preparing a compact set of parameters in advance that capture the essential filtering characteristics. This preliminary action eliminates the need to transmit full coefficient sets, reducing bandwidth requirements while preserving filtering accuracy
3Reliability
If universal multipliers are implemented for each pixel block to improve filtering precision, then filtering effectiveness is improved, but processing complexity and time increase
Solution Approach 1:
Filter coefficients are pre-calculated and stored in lookup tables during parameter optimization. This preliminary computation eliminates the need for real-time multiplication operations during video decoding, maintaining filtering precision while significantly improving processing speed by replacing complex calculations with simple table lookups
Data Source
AI summary
A filter is configured for processing a reconstructed frame for generation of a filtered reconstructed frame, and wherein the reconstructed frame comprises a plurality of pixels. The filter includes one or more processor configured to scan a current pixel of the reconstructed block and its neighboring pixels of the current pixel according to a predefined scan template, obtain spectrum components by performing transform for the current pixel and its neighboring pixels, obtain filtered spectrum components based on a filtering parameter and the spectrum components, obtain filtered pixels by performing inverse transform for the filtered spectrum components, and generate a filtered reconstructed block based on the filtered pixels.