Video Sub-Bitstream Extraction With Conforming POC and SEI Handling
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Solution Overview
Problem
Current video coding technologies face challenges in bitstream conformance, particularly with Picture Order Count (POC) constraints and subpicture sub-bitstream extraction processes, leading to non-conforming bitstreams during sub-bitstream extraction and merging of video content.
Innovation Solution
The proposed solution involves modifying the POC constraints and sub-bitstream extraction processes to ensure that bitstreams conform to specific rules regarding POC derivation and SEI message handling, allowing for correct derivation of POC values and proper extraction of sub-bitstreams, even in multi-layer bitstreams and during subpicture sub-bitstream extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sub-bitstream extraction process removes all SEI NAL units satisfying a condition, then the extraction efficiency is improved, but the bitstream conformance is compromised due to POC derivation issues
Solution Approach 1:
The patent applies preliminary action by inserting replacement POC information into SEI messages before removing SEI NAL units during sub-bitstream extraction. This ensures that POC derivation can be correctly performed in the extracted bitstream even after SEI message removal, maintaining bitstream conformance while achieving extraction efficiency.
2Loss of information
If multiple SEI messages are associated with the same access unit or decoding unit, then the information completeness is improved, but the bitstream complexity increases due to redundant messages
Solution Approach 1:
The patent merges multiple SEI messages with the same payload type associated with the same access unit or decoding unit into a single representative message. This reduces bitstream complexity by eliminating redundant messages while preserving the essential information, as the merged message contains the same payload content that would be present in any of the original messages.
3Speed
If the sub-bitstream extraction process is simplified by removing unnecessary steps, then the processing speed is improved, but the SEI message consistency across layers may be compromised
Solution Approach 1:
The patent applies local quality by selectively applying the SEI message consistency rule only to messages with the same payload type that are associated with the same access unit or decoding unit. This targeted approach ensures SEI message consistency where needed while allowing processing speed improvements in other areas of the bitstream extraction process.
Data Source
AI summary
Systems, methods and apparatus for encoding, decoding or transcoding digital video are described. One example method of video processing includes performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to an order of a sub-bitstream extraction process that is defined by a rule that specifies (a) the sub-bitstream extraction process excludes an operation that removes all supplemental enhancement information (SEI) network abstraction layer (NAL) units, which satisfy a condition, from an output bitstream or (b) the order of the sub-bitstream extraction process includes replacing parameter sets with replacement parameter sets prior to removing, from an output bitstream, the SEI NAL units.