Video Coding Syntax Element Constraints for Subpicture Handling
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Solution Overview
Problem
Current video encoding and decoding technologies face challenges in efficiently signaling and constraining syntax elements, leading to increased power consumption, compression complexity, and decoding complexity, particularly in handling subpicture information and reference picture lists in video bitstreams.
Innovation Solution
The implementation of General Constraint Information (GCI) flags and modified semantics to constrain various syntax elements, such as subpicture information presence and reference picture list elements, allowing video encoders to selectively disable unsupported coding tools and enable adaptive streaming by signaling these constraints within the bitstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If video decoders parse sequence parameter set (SPS) or picture parameter set (PPS) to check support for coding features, then decoding accuracy is improved, but decoding complexity and power consumption increase
Solution Approach 1:
The patent introduces a preliminary syntax element in the bitstream that indicates whether subpicture information is present before the decoder needs to parse SPS or PPS. This preliminary indication allows the decoder to quickly determine if it should proceed with full parameter set parsing or discard the bitstream, thereby reducing unnecessary decoding complexity and power consumption while maintaining decoding accuracy when needed
Solution Approach 2:
The patent extracts the critical constraint information (presence of subpicture information) from the complex SPS/PPS parameter sets and places it as a separate, easily parseable syntax element in the bitstream. This extraction allows decoders to check for supported features without having to parse the entire parameter set structure, reducing decoding complexity while preserving the ability to accurately identify unsupported bitstreams
2Productivity
If video encoders use multiple coding tools for different video content, then compression efficiency is improved, but compression complexity and power consumption increase
Solution Approach 1:
The patent enables dynamic selection of coding tools by introducing a syntax element that indicates the presence of subpicture information. Encoders can adaptively choose whether to use subpicture-related coding tools based on the actual content characteristics, allowing the system to switch between different coding modes dynamically. This maintains high compression efficiency for content that benefits from subpicture coding while avoiding the complexity overhead for content that does not require it
Solution Approach 2:
The patent applies different coding approaches to different regions or types of video content by using the syntax element to indicate where subpicture information is present. This allows the encoder to apply sophisticated subpicture coding tools only to specific regions or content types where they are beneficial, while using simpler coding methods elsewhere, thereby maintaining overall compression efficiency while reducing average compression complexity
3Manufacturing precision
If video bitstreams include detailed subpicture information and reference picture list elements, then video quality is improved, but bitstream complexity and processing overhead increase
Solution Approach 1:
The patent segments the bitstream structure by introducing a syntax element that clearly delimits the presence and scope of subpicture information. This segmentation allows receivers to quickly identify and process only the relevant portions of the bitstream containing subpicture data, rather than having to parse through entire parameter sets. The detailed subpicture information and reference picture list elements are organized in a structured, hierarchical manner that reduces processing overhead while preserving video quality
Solution Approach 2:
The patent introduces an intermediary syntax element that acts as a mediator between the detailed subpicture information and the rest of the bitstream structure. This intermediary element provides a clear indication of subpicture presence and scope, allowing receivers to efficiently navigate and process the bitstream without being overwhelmed by its complexity. The intermediary syntax element enables selective parsing of detailed subpicture data only when needed, maintaining video quality while reducing overall processing overhead
Data Source
AI summary
An example method includes decoding, from a coded video bitstream, a first syntax element that specifies a constraint for a second syntax element that specifies whether subpicture information is present in the coded video bitstream and whether more than one subpicture is allowed to be present in the coded video bitstream; and decoding, based on the constraint specified by the first syntax element, the second syntax element.