Subpicture Sub-bitstream Extraction Scaling Window Offset Rewriting
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Solution Overview
Problem
The existing subpicture sub-bitstream extraction process in VVC lacks the ability to rewrite scaling window offset parameters, leading to inconsistencies when extracting rectangular regions from video sequences, and has constraints that limit the combinations of subpictures from different layers that can form a conforming bitstream.
Innovation Solution
The proposed solution involves calculating and rewriting the scaling window offset parameters during the subpicture sub-bitstream extraction process, and specifying rules for the extraction of sub-bitstreams that ensure all layers in an output layer set have the same spatial resolution and subpicture layout, allowing for the correct formatting of the output bitstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the existing subpicture sub-bitstream extraction process is used, then the extraction process is simple, but the scaling window offset parameters cannot be rewritten leading to inconsistencies
Solution Approach 1:
The patent applies preliminary action by calculating and rewriting scaling window offset parameters during the subpicture sub-bitstream extraction process. This ensures that the parameters are correctly updated before the extraction is completed, preventing inconsistencies in the output bitstream while maintaining a manageable process complexity.
2Adaptability or versatility
If constraints are imposed on subpicture combinations, then the bitstream conformance is ensured, but the flexibility in forming conforming bitstreams is limited
Solution Approach 1:
The patent applies parameter changes by relaxing the constraints on subpicture combinations through updated extraction rules. These rule changes allow for a wider range of subpicture combinations to form conforming bitstreams, thereby increasing adaptability while maintaining reliability through the structured framework of the updated rules.
3Manufacturing precision
If the scaling window parameters are not updated, then the extraction process is fast, but the output bitstream has inconsistencies
Solution Approach 1:
The patent performs the scaling window parameter updates as a preliminary action during the extraction process. By integrating the parameter rewriting into the extraction workflow, the patent ensures bitstream consistency is maintained without requiring separate post-processing steps, thus preserving extraction speed.
Data Source
AI summary
Embodiments for video processing, including video coding, video decoding and video transcoding are described. One example method includes performing a conversion between a video having one or more layers having one or more video pictures having one or more subpictures and a bitstream of the video according to a rule, in which the rule defines network abstraction layer (NAL) units to be extracted from a bitstream during a sub-bitstream extraction process to output a sub-bitstream, the rule further specifies that one or more inputs to the sub-bitstream extraction process include a target output layer set (OLS) index (targetOlsIdx) that identifies an OLS index of a target OLS and is equal to an index to a list of OLSs specified by a video parameter set, and the one or more inputs satisfy a set of conditions.