Operation Point Sample Group Alignment in Multi-Layer Bitstreams
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Solution Overview
Problem
The ISO base media file format for storing L-HEVC bitstreams faces challenges in accurately defining operation points due to misalignment of samples across different tracks, leading to incomplete extraction of operation points and inefficient data forwarding, especially in bandwidth-constrained environments.
Innovation Solution
The proposed solution involves determining whether a sample in an additional track is part of an operation point information sample group by checking temporal colocation with the operation point reference track, considering it part of the group if collocated or the last sample before it if not, and performing a sub-bitstream extraction process to extract the operation point effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If samples in additional tracks are not aligned with the operation point reference track, then the file format can accommodate different frame rates and provide more flexibility, but the operation point extraction becomes incomplete and inaccurate
Solution Approach 1:
The patent applies preliminary action by establishing temporal colocation relationships between samples in additional tracks and the operation point reference track before performing operation point extraction. By pre-determining which samples are temporally collocated and should be grouped together, the system ensures accurate operation point identification even when frame rates differ across tracks. This preliminary grouping mechanism resolves the contradiction by maintaining extraction accuracy while supporting frame rate flexibility.
2Productivity
If operation point information is not accurately identified due to sample misalignment, then data redundancy increases and forwarding efficiency decreases, but maintaining strict sample alignment would limit frame rate variations
Solution Approach 1:
The patent introduces temporal colocation as an intermediary concept that mediates between samples in additional tracks and the operation point reference track. This intermediary mechanism allows the system to accurately identify operation points by establishing temporal relationships without requiring strict sample alignment, thereby maintaining information completeness while enabling efficient data forwarding with reduced redundancy.
3Measurement precision
If samples are grouped based on temporal colocation with the operation point reference track, then operation points can be accurately extracted even with different frame rates, but the complexity of determining sample group membership increases
Solution Approach 1:
The patent applies segmentation by dividing the complex task of operation point identification into manageable segments: first identifying temporally collocated samples between additional tracks and the reference track, then grouping these samples into operation point information sample groups. This segmented approach reduces determination complexity while maintaining identification accuracy by breaking down the problem into sequential, simpler steps.
Data Source
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AI summary
An apparatus obtains an operation point reference track in the file and one or more additional tracks in the file. No operation point information sample group is signaled in any of the additional tracks. For each respective sample of each respective additional track of the one or more additional tracks, the apparatus determines whether to consider the respective sample part of the operation point information sample group. Based on the operation point reference track not containing a sample that is temporally collocated with the respective sample in the respective additional track, the respective sample in the respective additional track is considered part of an operation point information sample group of the last sample in the operation point reference track before the respective sample of the respective additional track.