Video Sublayer Reference Rules for Multi-Layer Decoding Order
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Solution Overview
Problem
Existing video coding standards face challenges in efficiently managing subpicture types and their decoding order, output order, and prediction relationships, particularly in multi-layer video coding contexts, which affects bandwidth usage and decoding efficiency.
Innovation Solution
The proposed methods define specific format rules for converting video into coded representations that specify the inclusion of subpictures in NAL units, enforce consistent subpicture types, and establish constraints on their occurrence and relationships, allowing for efficient decoding and processing in both single-layer and multi-layer video coding scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If video coding standards use multiple subpicture types with different NAL unit types, then video representation flexibility and adaptability are improved, but decoding complexity and processing difficulty increase
Solution Approach 1:
The video picture is divided into multiple subpictures, each with its own NAL unit type and independent decoding characteristics. This segmentation allows different regions of the picture to be encoded and decoded with different complexities and requirements, improving overall adaptability while managing decoding complexity through localized processing
Solution Approach 2:
The patent introduces a hierarchical dimension to video coding by organizing subpictures within pictures within video streams, with multiple layers of structure. This dimensional organization allows for systematic management of complexity at each level while maintaining flexibility in representation
2Productivity
If subpictures are encoded with different NAL unit types, then coding efficiency and bandwidth optimization are improved, but decoding order determination and synchronization become more difficult
Solution Approach 1:
The patent establishes predetermined rules and syntax elements in advance that define the decoding order of subpictures with different NAL unit types. By pre-defining the relationships and ordering constraints in the bitstream syntax, decoders can determine decoding order without complex runtime analysis, maintaining coding efficiency while simplifying order determination
3Reliability
If reference picture constraints are enforced for inter-layer prediction, then decoding reliability and picture quality are improved, but the number of valid reference pictures and coding flexibility are reduced
Solution Approach 1:
The patent applies different reference picture constraints locally to specific subpicture types and layers rather than uniformly across the entire video stream. This allows high-reliability constraints to be applied where needed for decoding stability while maintaining coding flexibility in other regions, resolving the contradiction between reliability and adaptability
Data Source
AI summary
Methods and apparatus for processing of video are described. A video processing method includes performing a conversion between a video including multiple layers of one or more pictures and a bitstream of the video according to a format rule. The format rule specifies that a reference picture referred to by each inter-layer reference picture entry in a reference picture list of a slice of a current picture of a current layer satisfies a constraint. The constraint is at least one of: (a) the reference picture is an intra random access (IRAP) picture or (b) the reference picture has a temporal identifier that is less than or equal to a certain value that is a function of a maximum allowed value of a video layer to which slices from the current layer can reference. The maximum allowed value is indicated in a syntax element.