Layered Compressed HOA Decoding for Scalable Spatial Audio
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Solution Overview
Problem
Existing HOA compression methods provide a monolithic compressed representation, lacking scalability and the ability to split into a low quality base layer and a high quality enhancement layer, which is desirable for applications like broadcasting and internet streaming.
Innovation Solution
Incorporate predominant sound components at a low spatial resolution into the base layer, allowing the HOA compression to operate in a layered mode with a base layer and an enhancement layer, and modify the HOA decompression to handle this layered structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If HOA compression uses a monolithic representation, then the compression structure is simple, but scalability and adaptability to different transmission conditions are lost
Solution Approach 1:
The patent divides the compressed HOA representation into multiple layers: a base layer containing essential ambient HOA components and an enhancement layer containing additional predominant sound components. This segmentation enables scalable decoding where the base layer can be decoded independently for robustness, while the enhancement layer adds quality when available
Solution Approach 2:
The patent implements a nested structure where the base layer is embedded within the full representation, and the enhancement layer contains supplementary information. The base layer includes transformed ambient HOA components that can be independently decoded, while the enhancement layer adds predominant sound components that nest within the same decoded structure
2Measurement precision
If HOA representation includes all expansion coefficients, then spatial resolution is high, but transmission data rate becomes excessively high
Solution Approach 1:
The patent extracts and separates predominant sound components from the full HOA representation to form an enhancement layer. By identifying and extracting only the most significant components for a given application, the patent reduces the data rate while preserving essential spatial information
Solution Approach 2:
The patent applies different quality levels to different parts of the HOA representation by encoding ambient components in the base layer at a resolution appropriate for robust transmission, while optional predominant sound components in the enhancement layer provide enhanced local quality where needed
Data Source
AI summary
Methods and apparatus for decoding a compressed Higher Order Ambisonics (HOA) representation of a sound or soundfield. The method may include receiving a bit stream containing the compressed HOA representation and decoding, based on a determination that there are multiple layers, the compressed HOA representation from the bitstream to obtain a sequence of decoded HOA representations. A first subset of the sequence of decoded HOA representations is determined based only on corresponding ambient HOA components. A second subset of the sequence of decoded HOA representations is determined based on corresponding ambient HOA components and corresponding predominant sound components.