Lossless Video Coding Decoder for Selective Tool Disabling
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Solution Overview
Problem
Existing video coding standards face challenges in achieving lossless compression with low bit-rates due to redundant lossless coding abilities, such as transform quantization bypass and transform skipping functionality, and the need to modify behavioral details of coding tools like adaptive loop filters and reshaper tools.
Innovation Solution
The solution involves disabling certain tools for processing prediction residuals and enabling lossless coding without explicit signaling, using different binarizations, perfectly invertible transforms, and controlling quantization accuracy based on coding parameters to reduce bit rates and computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transform quantization bypass and transform skipping functionality are enabled for lossless coding, then lossless reconstruction is achieved, but bit rate increases and device complexity increases
Solution Approach 1:
The patent extracts and disables specific post-reconstruction tools (adaptive loop filter, reshaper tool) selectively in lossless coding regions. By removing only the necessary complex processing steps while maintaining the core lossless reconstruction capability through transform quantization bypass, the solution achieves lossless reconstruction with reduced device complexity and lower bit rates.
2Manufacturing precision
If adaptive loop filter and reshaper tools are enabled for processing prediction residuals, then coding quality is improved, but bit rate increases and device complexity increases
Solution Approach 1:
The patent applies different processing qualities to different regions: in lossless regions, post-reconstruction tools are disabled to maintain exact reconstruction with lower complexity, while in lossy regions, these tools remain enabled to improve coding quality. This local differentiation resolves the contradiction by applying complexity only where beneficial.
Solution Approach 2:
The patent dynamically controls the enablement of adaptive loop filter and reshaper tools based on the coding mode (lossless vs. lossy). The tools are selectively activated or deactivated according to the region type, allowing the system to adapt processing complexity to the specific requirements of each region, thereby optimizing the balance between coding quality and device complexity.
3Adaptability or versatility
If multiple coding tools are enabled for processing prediction residuals, then coding flexibility is improved, but device complexity increases
Solution Approach 1:
The patent segments the video content into lossless regions and lossy regions, applying different tool sets to each segment. In lossless regions, only essential tools are enabled while post-reconstruction tools are disabled. In lossy regions, the full set of tools remains available. This segmentation maintains coding flexibility across different regions while reducing overall device complexity.
4Measurement precision
If lossless coding is implemented with explicit signaling, then coding accuracy is improved, but bit rate increases
Solution Approach 1:
The patent enables the decoder to self-detect lossless regions by examining coding parameters (quantization parameter QP≤4, transform skip mode, bypass flag) without requiring explicit lossless region signaling. This self-service approach maintains coding accuracy for lossless regions while avoiding the additional bit rate overhead that would result from explicit signaling of lossless regions.
Data Source
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AI summary
Decoder for decoding a picture from a data stream, configured to check (106) whether a plurality (98) of coding parameters, which are contained in the data stream (14), relate to a predetermined portion (100) of the picture (12) and control a prediction residual transform mode and a quantization accuracy with respect to the predetermined portion, are indicative of a coding parameter setting corresponding to a lossless prediction residual coding. Responsive to the plurality of coding parameters being indicative of the coding parameter setting corresponding to the lossless prediction residual coding, the decoder is configured to set one or more predetermined coding options relating to one or more tools of the decoder for processing a prediction residual corrected predictive reconstruction with respect to the predetermined portion so that the one or more tools are disabled with respect to the predetermined portion.