Wavefront Parallel Processing with Unified Tile and CTB Signaling
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Solution Overview
Problem
Existing video coding technologies suffer from unnecessary duplication of signaling and byte alignment in wavefront parallel processing (WPP), leading to increased bit usage and reduced efficiency in video compression and decompression processes.
Innovation Solution
Implement techniques that eliminate the duplication of signaling and byte alignment in WPP by using end of tile and CTB row bits with specific values and byte alignment bits to reduce the number of bits required for signaling and padding, thereby improving the efficiency of video coding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wavefront parallel processing (WPP) is implemented with traditional signaling methods, then parallel processing capability is improved, but the number of bits used for signaling and byte alignment is increased
Solution Approach 1:
The patent merges the end of tile signaling and end of CTB row signaling into a single unified signaling mechanism. By using a single bit to indicate both the end of a tile and the end of a CTB row when WPP is enabled, the patent eliminates redundant signaling bits while maintaining the parallel processing capability provided by WPP.
Solution Approach 2:
The patent makes the end of tile bit serve multiple functions: it indicates both the end of a tile in traditional mode and the end of a CTB row in WPP mode. This multi-functional bit reduces the total number of signaling bits required while supporting both processing modes through conditional interpretation based on the WPP enable flag.
2Reliability
If byte alignment bits are added for each tile boundary in WPP, then alignment requirements are satisfied, but the total number of bits in the bitstream is increased
Solution Approach 1:
The patent extracts and eliminates redundant byte alignment bits from the bitstream by recognizing that when WPP is enabled, the end of tile bit already provides the necessary alignment information. By removing duplicate alignment bits that would otherwise be added at tile boundaries, the patent reduces total bitstream size while maintaining proper byte alignment for parallel processing.
3Manufacturing precision
If separate signaling for end of tile and end of CTB row is implemented, then processing accuracy is improved, but the complexity of the coding system is increased
Solution Approach 1:
The patent inverts the traditional approach by using the end of tile bit to serve dual purposes. Instead of adding separate signaling for end of CTB row, the patent repurposes the existing end of tile bit to indicate both end of tile and end of CTB row conditions, depending on the WPP enable flag. This inversion reduces signaling complexity while maintaining processing accuracy through conditional interpretation.
Data Source
AI summary
A method of decoding includes encountering an end of tile bit with a first value and byte alignment bits in a video bitstream, which indicate that a current coding tree block (CTB) is a last CTB in a tile; encountering an end of CTB row bit with the first value and the byte alignment bits in the video bitstream, which indicate that waveform parallel processing (WPP) is enabled and that the current CTB is the last CTB in a CTB row but not the last CTB in the tile; and reconstructing the plurality of CTBs in the tile based on the end of tile bit with the first value, the end of CTB row bit with the first value, and the byte alignment bits.