Video Stream Random Access Encapsulation via NAL Unit Grouping
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Solution Overview
Problem
The existing mechanisms for random access in video streams, particularly with the versatile video codec (VVC), face challenges due to dependencies between video coding layer (VCL) and non-VCL network abstraction layer units (NAL units), which are not adequately addressed by current standards like ISOBMFF, leading to inefficiencies in decoding and resource utilization.
Innovation Solution
A method and device that generate a specific data structure, including a SampleToGroupBox and associated SampleGroupDescriptionBox, to identify and encapsulate NAL units, enabling efficient random access by referencing required NAL units for decoding, thereby improving video streaming and decoder resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If VCL NAL units in random access pictures reference non-VCL NAL units from previous picture units, then compression performance is improved through adaptive loop filter and parameter sets, but random access capability deteriorates because previous picture units must be available for decoding
Solution Approach 1:
The patent applies preliminary action by including all necessary non-VCL NAL units (parameter sets, adaptation parameter sets) with the random access picture in the ISOBMFF encapsulation. This pre-positioning of required data eliminates the need to access previous picture units during random access, allowing decoders to start decoding immediately from any random access picture without requiring prior pictures to be available.
2Productivity
If non-VCL NAL units are referenced from previous picture units, then decoding efficiency is improved through shared parameter sets, but storage and transmission complexity increases due to dependency management
Solution Approach 1:
The patent applies segmentation by separating VCL NAL units (picture data) and non-VCL NAL units (parameter sets) into distinct encapsulation structures in ISOBMFF. Each random access picture is associated with its required non-VCL NAL units through sample-to-group descriptions, creating independent decodable units. This segmentation eliminates complex dependency tracking while maintaining decoding efficiency through organized parameter set association.
Solution Approach 2:
The patent introduces ISOBMFF encapsulation structure as an intermediary between the VVC bitstream and the decoder. This intermediary layer manages the complexity of NAL unit dependencies by providing a standardized container format that organizes VCL and non-VCL NAL units with explicit association relationships, simplifying storage, transmission, and random access operations.
3Loss of energy
If random access pictures depend on previous picture units, then compression performance is maintained through continuous parameter set updates, but bandwidth utilization deteriorates due to redundant data transmission
Solution Approach 1:
The patent applies the taking out principle by extracting non-VCL NAL units from their original positions in previous picture units and re-encapsulating them with the random access picture they depend on. This extraction eliminates redundant transmission of parameter sets and ensures that only the necessary data for each random access picture is transmitted, optimizing bandwidth utilization while maintaining compression performance.
Data Source
AI summary
A method for encapsulating a video bit-stream in a server, including obtaining at least one network abstraction layer unit (NAL unit) of a first picture, buffering the at least one obtained NAL unit, obtaining at least one NAL unit of a second picture, the second picture being a random access picture following the first picture, and encapsulating the at least one obtained NAL unit of the second picture and the at least one buffered NAL unit in an encapsulation structure making it possible to generate a video bit-stream without processing the encapsulated at least one buffered NAL unit when processing the encapsulated video bit-stream.