Video File Parsers with Parameter Sets for Open GOP Switching
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Solution Overview
Problem
In video coding environments, particularly in adaptive HTTP streaming, issues arise during track or representation switching, especially when using open GOP structures, leading to potential quality degradation and decoder initialization challenges due to missing reference pictures during resolution changes.
Innovation Solution
A file parser and generator are used to reconstruct and generate video bitstreams by identifying switch-to candidates and providing initialization parameter sets, allowing seamless switching between different tracks or representations, while ensuring correct decoder initialization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If open GOP resolution switching is used to achieve higher efficiency, then coding efficiency is improved, but decoder initialization complexity increases due to missing reference pictures during resolution changes
Solution Approach 1:
The patent applies preliminary action by pre-generating and storing alternative initialization parameter sets for different resolutions in the video file before playback. The file parser retrieves the appropriate initialization parameter set in advance based on the track switching information, ensuring the decoder is already prepared with the correct parameters before a resolution change occurs, thus avoiding re-initialization complexity during actual playback
Solution Approach 2:
The patent introduces an intermediary mechanism through the file parser that acts as a mediator between the track switching system and the decoder. The file parser retrieves alternative initialization parameter sets and inserts them into the bitstream at appropriate locations, serving as an intermediary that bridges the gap between open GOP switching and decoder requirements, thereby maintaining coding efficiency while simplifying decoder initialization
2Adaptability or versatility
If track switching is implemented for adaptive streaming, then adaptability is improved, but video quality degrades due to missing reference pictures during resolution changes
Solution Approach 1:
The patent applies preliminary action by pre-preparing alternative initialization parameter sets for different resolution tracks within the video file. When track switching occurs, the file parser retrieves the appropriate pre-stored initialization parameter set and inserts it into the bitstream before the resolution change, ensuring continuous video quality without degradation due to missing reference pictures
Solution Approach 2:
The patent uses copying by creating copies of initialization parameter sets for different resolutions and storing them in the video file. Instead of regenerating or re-encoding reference pictures during track switching, the system copies the appropriate pre-stored initialization parameter set into the bitstream, thereby maintaining video quality while enabling adaptive track switching
3Quantity of substance
If initialization parameter sets are stored out-of-band in sample entries, then storage efficiency is improved, but track switching reliability decreases due to parameter set mismatch during resolution changes
Solution Approach 1:
The patent applies segmentation by dividing the storage of initialization parameter sets into multiple segments: the primary out-of-band storage in sample entries for space efficiency, and additional alternative initialization parameter sets stored separately in the video file for reliability. The file parser manages these segmented storage locations and retrieves the appropriate parameters during track switching, thereby maintaining both storage efficiency and switching reliability
Solution Approach 2:
The patent uses parameter changes by dynamically selecting and switching between different initialization parameter sets based on the target track's resolution requirements. The file parser changes the parameter set selection dynamically during track switching, retrieving alternative initialization parameter sets when needed, thus maintaining reliability while preserving the space-efficient out-of-band storage approach
Data Source
AI summary
The present invention concerns file parsers, file generators encoders, decoders, clients, servers and methods using parameter sets for coded video sequences. Said parameter sets may have decoding parameter information and may be conveyed in-band or out-of band. Some embodiments provide solutions to problems being related with correctly initializing a decoder for decoding coded video sequences in open GOP switching scenarios. Some embodiments may provide for hierarchical track switching levels.