V-PCC Bitstream Grouping for User-Switchable Playback in ISOBMFF
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Solution Overview
Problem
Current media file formats, such as ISOBMFF, do not allow for multiple volumetric objects encoded in the same file to be switched as alternate representations during playback, limiting content creators' options for user-controlled playback experiences.
Innovation Solution
A method is introduced to write multiple video-based point cloud compression (V-PCC) bitstreams into a container file, associating them with a common logical context, and generating a media presentation description (MPD) file with adaptation sets, where grouping information indicates that these bitstreams are user-switchable alternatives, enabling switching between different V-PCC bitstreams based on logical context.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple volumetric objects are encoded in separate files, then each object can be independently managed, but switching between alternate representations during playback is not possible
Solution Approach 1:
The patent combines multiple V-PCC bitstreams representing different volumetric objects into a single container file using ISOBMFF structure. This merging enables the playback device to access and switch between multiple alternate representations stored in one file, resolving the contradiction by sacrificing some file structure simplicity to gain switching capability.
Solution Approach 2:
The container file structure is designed to serve multiple functions: storing multiple V-PCC bitstreams, maintaining grouping information for logical context association, and enabling playback switching. This multi-functionality allows a single file to provide both storage and dynamic switching capabilities.
2Adaptability or versatility
If multiple V-PCC bitstreams are grouped in the same container file, then switching between alternate representations becomes possible, but the file structure becomes more complex
Solution Approach 1:
The patent segments the container file into distinct components: V-PCC bitstreams are organized into separate tracks, each with its own adaptation set in the MPD file. Grouping information is separated into specific data structures that associate bitstreams with logical contexts. This segmentation manages complexity by creating modular, independently manageable units.
Solution Approach 2:
The MPD (Media Presentation Description) file acts as an intermediary between the container file and the playback device. It provides a structured description of the V-PCC bitstreams, adaptation sets, and grouping information, simplifying the interface and enabling the playback device to understand and switch between alternate representations without directly parsing the complex container file structure.
3Adaptability or versatility
If alternate representations are limited to same volumetric object, then switching is straightforward, but content creators lose versatility in providing user-controlled playback options
Solution Approach 1:
The patent introduces dynamic switching capability where the playback device can select between multiple V-PCC bitstreams representing different volumetric objects based on user preference and logical context. The grouping information enables dynamic association of alternate representations that were previously static and limited to single objects, allowing flexible user-controlled playback while maintaining operational simplicity through automated context management.
Data Source
AI summary
A method comprising: writing, in a container file, a first video-based point cloud compression (V-PCC) bitstream and a second V-PCC bitstream, wherein said first and second V-PCC bitstreams are associated with a common group based on at least one logical context; writing, in the container file, an indication about the common group between the first V-PCC bitstream and the second V-PCC bitstream; generating a media presentation description (MPD) file with a first representation belonging to a first adaptation set associated with the first V-PCC bitstream and a second representation belonging to a second adaptation set associated with the second V-PCC bitstream; and writing, in the MPD file, at least one information element describing grouping information of the first representation belonging to the first adaptation set and the second representation belonging to the second adaptation set, wherein said information element is provided with at least one attribute indicating that said first and second V-PCC bitstreams are user-switchable alternatives upon rendering.