Subpicture Level Signaling for Efficient VVC Sublayer Decoding
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Solution Overview
Problem
Existing video coding standards face challenges in efficiently managing subpicture sequences and level information, particularly in Versatile Video Coding (VVC), which affects bandwidth utilization and decoding efficiency in applications like 360° video streaming.
Innovation Solution
The implementation of subpicture level information (SLI) supplemental enhancement information (SEI) messages in VVC, specifying maximum sublayers, level indicators, and persistent information across access units, enables efficient management of subpicture sequences and enhances decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If subpicture level information (SLI) SEI messages include detailed level information for multiple sublayers, then decoding precision and bandwidth utilization improve, but message complexity and processing overhead increase
Solution Approach 1:
The SLI SEI message is segmented into multiple syntax structures, each corresponding to a specific sublayer. Each syntax structure contains level information (e.g., max_sublayers, level_idc, tier_idc) for that particular sublayer. This segmentation allows the decoder to process level information for each sublayer independently, improving precision while managing complexity through modular processing.
Solution Approach 2:
The patent introduces a loop dimension that iterates through multiple sublayers, with each iteration processing a specific syntax structure for that sublayer. This dimensional approach transforms the complexity from a flat monolithic structure into a hierarchical multi-dimensional structure, enabling precise level information to be conveyed for each sublayer while organizing the data in a systematic manner that facilitates efficient processing.
2Productivity
If SLI SEI messages are made persistent across multiple access units, then decoding efficiency improves, but memory requirements and processing load increase
Solution Approach 1:
The SLI SEI message is decoded and stored in advance across multiple access units, making the level information available before it is needed for actual decoding operations. This preliminary action allows the decoder to have level information ready, improving decoding efficiency by avoiding repeated parsing and processing of the same level data across multiple access units.
Solution Approach 2:
The persistent SLI SEI message structure is designed to serve multiple access units simultaneously. A single SLI SEI message can provide level information for multiple sublayers across multiple access units, making the data structure multi-functional. This universality reduces the total amount of level information that needs to be stored and processed, as the same syntax structures serve multiple purposes across different access units.
Data Source
AI summary
Several techniques for video encoding and video decoding are described. One example method includes performing a conversion between a video and a bitstream of the video including one or more output layer sets (OLSs) according to a rule. The rule specifies that a subpicture level information (SLI) supplemental enhancement information (SEI) message includes information about a level of subpicture sequences in a set of coded video sequences of the one or more OLSs to which the SLI SEI message applies. A syntax structure of the SLI SEI message includes at least (1) a first syntax element specifying a maximum number of sublayers for the subpicture sequences and (2) a second syntax element specifying whether level information for the subpicture sequences is present for one or more sublayer representations.