3D Audio Scene Trees for Low-Bitrate Spatial Rendering
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Solution Overview
Problem
Existing scene graph data structures for managing relationships between sound sources and listener positions in 3D scenes are inefficient and require significant data, especially in low-bitrate streaming scenarios, leading to suboptimal bitrate efficiency and media presentation quality.
Innovation Solution
The use of a scene tree structure to encode audio signals and metadata into a bitstream, where positions of sound sources are defined relative to sub-scene origins within a 3D scene, allowing efficient spatial rendering and reduced data requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional scene graph data structures are used to manage sound source positions in 3D scenes, then spatial rendering accuracy is maintained, but data transmission bitrate increases significantly
Solution Approach 1:
The patent divides the 3D scene into hierarchical levels (global scene, sub-scenes, and sound sources within sub-scenes). Position data is segmented and encoded at different hierarchical levels, where sub-scene positions are encoded relative to the global scene origin, and sound source positions are encoded relative to their sub-scene origins. This segmentation reduces redundancy in position data transmission while maintaining spatial rendering accuracy.
Solution Approach 2:
The patent implements a nested hierarchical structure where sub-scenes are nested within the global 3D scene, and sound sources are nested within their respective sub-scenes. Each level contains position information relative to its parent level's origin, creating a nested coordinate system that minimizes data transmission requirements while preserving spatial relationships.
2Measurement precision
If complete position data for all sound sources is transmitted in every metadata update, then spatial accuracy is maintained, but bitrate efficiency deteriorates
Solution Approach 1:
The patent extracts and transmits only the essential position information needed for spatial rendering. Instead of transmitting complete position data for all sound sources in every metadata update, it extracts and transmits only the changes in sub-scene origins and sound source positions relative to their parents, significantly reducing bitrate requirements while maintaining position accuracy.
Solution Approach 2:
The patent changes the parameter representation from absolute positions to relative position offsets. Position data is encoded as offsets from parent origins rather than absolute coordinates, and only changes in these parameters are transmitted in metadata updates. This parameter transformation reduces data transmission volume while preserving the ability to accurately reconstruct sound source positions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient encoding and rendering of 3D audio scenes with minimal data, maintaining high-quality spatial audio experiences even in low-bitrate conditions, by reducing redundancy and optimizing position updates.
Implementation Method 1
the spatial filter is a head-related transfer function, and the electronic device is a headset
Data Source
AI summary
A method that includes receiving a first bitstream that includes an encoded version of an audio signal for a three-dimensional (3D) scene and a first set of metadata that has 1) a position of a 3D sub-scene within the scene and 2) a position of a sound source associated with the audio signal within the sub-scene; determining a position of a listener; spatially rendering the scene to produce the sound source with the audio signal at the position of the sound source with respect to the position of the listener; receiving a second bitstream that includes a second set of metadata that has a different position of the sub-scene; and adjusting the spatial rendering of the scene such that the position of the sound source changes to correspond to movement of the sub-scene from the position of the sub-scene to the different position of the sub-scene.