Video Block Decoding With Signaled CTU and Transform Size Constraints
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Solution Overview
Problem
The existing video coding standards, such as VVC, lack efficient mechanisms for constraining and signaling the maximum block sizes during the decoding process, leading to potential inefficiencies and complexity in video decoding.
Innovation Solution
Implementing a method for decoding an image frame by constraining and signaling the maximum transform block size and coding tree unit size using fixed-length codewords, allowing for more precise control over the decoding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable-length codewords are used for signaling maximum block sizes, then flexibility in encoding is improved, but computational complexity and decoding difficulty increase
Solution Approach 1:
The maximum block size signaling is segmented into multiple syntax elements (max_transform_block_size_constraint, max_coding_tree_unit_size_constraint, max_enabled_transform_block_size, max_enabled_coding_tree_unit_size) that are decoded separately and combined. This segmentation allows the system to maintain flexibility while reducing individual element complexity and enabling parallel decoding processing.
Solution Approach 2:
The patent introduces new parameters (constraint flags and enabled size values) that modify the traditional block size signaling mechanism. These parameter changes enable a two-stage control system where constraints limit the search space and enabled sizes provide precise control, reducing decoding complexity while maintaining encoding flexibility.
2Device complexity
If maximum block size constraints are not signaled, then bitstream simplicity is maintained, but decoding accuracy and control precision deteriorate
Solution Approach 1:
The maximum block size constraints are signaled in advance during sequence parameter set decoding, before actual video block decoding begins. This preliminary action establishes the decoding rules and limits upfront, enabling efficient runtime decoding while maintaining high control precision through pre-configured constraints and enabled size values.
3Measurement precision
If separate constraints for transform blocks and coding tree units are implemented, then control precision is improved, but signaling overhead increases
Solution Approach 1:
The patent merges the constraint signaling for transform blocks and coding tree units into a unified framework where max_transform_block_size_constraint and max_coding_tree_unit_size_constraint are decoded from the same bitstream location. This merging reduces redundancy while maintaining separate control precision for different block types through the enabled size parameters.
Data Source
AI summary
Decoding an image frame from a bitstream, the image frame being divided into a plurality of coding tree units. The method comprises decoding a maximum transform block size constraint and or a maximum coding tree unit (CTU) size constraint from the bitstream; and decoding a maximum enabled transform block size and/or a maximum enabled CTU size from the bitstream. The decoded maximum enabled transform block size is less than or equal to the decoded maximum transform block size constraint. The decoded maximum enabled CTU size is less than or equal to the decoded maximum CTU size constraint. Determining each of the one or more transform blocks for each of the plurality of coding tree units according to the decoded maximum enabled transform block size, maximum enabled CTU and split flags decoded from the bitstream; and decode each of the determined one or more transform blocks from the bitstream.