Video Decoder Asymmetrical Deblocking for Transform-Basis Errors
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Solution Overview
Problem
Existing video coding technologies face challenges in effectively reducing errors at block boundaries due to varying error distributions caused by different transform bases, leading to inefficient deblocking filtering.
Innovation Solution
An encoder and decoder that determine an asymmetrical filter characteristic for block boundaries based on the combination of bases used to transform neighboring blocks, adjusting filter coefficients and thresholds to minimize error influence and enhance error reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetrical deblocking filtering is applied to block boundaries, then filtering simplicity is maintained, but error reduction effectiveness deteriorates due to varying error distributions from different transform bases
Solution Approach 1:
The patent applies asymmetry by determining different filter characteristics for blocks on opposite sides of a block boundary. Specifically, when neighboring blocks use different transform bases (e.g., DST-VII and DCT-II), the patent assigns different filter coefficients or filter types to each block side, matching the asymmetrical error distribution patterns caused by different basis transformations. This resolves the contradiction by sacrificing symmetrical simplicity to achieve superior error reduction effectiveness.
Solution Approach 2:
The patent implements local quality by adapting filter characteristics to local conditions at block boundaries. The filter characteristic for each block is determined based on the specific transform basis used by that block and its neighboring blocks. This localized adaptation allows the filtering process to optimize error reduction for each specific boundary context, rather than applying a uniform symmetrical filter, thereby improving manufacturing precision (error reduction) while maintaining reasonable process complexity.
2Device complexity
If deblocking filtering uses uniform filter characteristics for all blocks, then processing complexity is reduced, but coding efficiency deteriorates due to inability to address specific error distribution patterns
Solution Approach 1:
The patent applies dynamics by making filter characteristics adaptive rather than static. The filter characteristic for each block is dynamically determined based on the transform bases used by neighboring blocks. This dynamic adaptation allows the system to respond to varying error distribution patterns at different block boundaries, improving coding efficiency without requiring excessively complex processing, as the adaptability is based on readily available transform basis information.
Solution Approach 2:
The patent implements parameter changes by modifying filter characteristics (such as filter coefficients or filter type selection) based on the transform bases of neighboring blocks. When blocks use different transform bases, the patent changes the filter parameters accordingly to match the error distribution patterns. This parameter adaptation improves coding efficiency by addressing specific error patterns while maintaining manageable processing complexity through systematic parameter selection.
3Manufacturing precision
If asymmetrical filter characteristics are determined based on transform base combinations, then error reduction effectiveness is improved, but device complexity increases due to additional determination logic
Solution Approach 1:
The patent applies preliminary action by determining filter characteristics based on transform basis information that is already available from the encoding process. The transform bases are selected and known before deblocking filtering is applied, allowing the filter characteristics to be predetermined based on these known parameters. This preliminary determination based on available information reduces the need for complex real-time analysis during filtering, thereby improving error reduction effectiveness while limiting the increase in device complexity.
Solution Approach 2:
The patent implements copying by using the transform basis information from neighboring blocks to determine filter characteristics. Rather than performing complex error analysis, the system copies or references the transform basis properties to infer appropriate filter characteristics. This approach improves error reduction effectiveness by capturing the essential error distribution patterns while avoiding the complexity of direct error measurement and analysis.
Data Source
AI summary
A decoder includes a memory and processing circuitry. The processing circuitry, in operation, changes values of pixels in a first block and a second block to filter a boundary therebetween, using clipping such that change amounts of the respective values are within respective clip widths. The clip widths for the pixels in the first block and the second block are selected based on block sizes of the first block and the second block. The pixels in the first block include a first pixel located at a first position, and the pixels in the second block include a second pixel located at a second position corresponding to the first position with respect to the boundary. The clip widths include a first clip width and a second clip width corresponding to the first pixel and the second pixel, respectively, and the first clip width is different from the second width.