Head-Related Filter Generation with Structured Basis Functions
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Solution Overview
Problem
Existing methods for generating head-related filters for spatial audio rendering are inefficient, particularly in terms of computational complexity and memory usage, especially in limited-capacity devices like mobile devices, and often result in inaccurate or ambiguous object locations due to sparsely-sampled HR filter measurements.
Innovation Solution
A method for generating head-related filters using a structured representation of basis functions, including compact sampling and metadata for efficient storage and computation, allowing for real-time HR filter evaluation with reduced complexity and memory consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional HR filter measurement and storage methods are used, then measurement accuracy is maintained, but computational complexity and memory usage increase significantly
Solution Approach 1:
The patent segments the continuous spherical space into a finite number of discrete measurement points arranged in elevation and azimuth angles. HR filters are measured only at these discrete points rather than continuously, reducing measurement and storage requirements while maintaining spatial accuracy through systematic sampling of the acoustic environment.
Solution Approach 2:
The patent transforms HR filter data from time-domain impulse responses to frequency-domain representations using Fourier transforms. This parameter transformation enables more efficient storage and processing of spectral data, reducing computational complexity while preserving the essential acoustic characteristics needed for spatial audio rendering.
2Measurement precision
If densely-sampled HR filter measurements are taken, then spatial accuracy improves, but measurement time and data processing load increase
Solution Approach 1:
The patent applies partial sampling by measuring HR filters at a selectively chosen subset of spherical coordinates rather than densely sampling the entire sphere. The elevation and azimuth angles are sampled at optimized intervals that provide sufficient spatial accuracy for audio rendering while significantly reducing the total number of measurements required compared to exhaustive sampling.
Solution Approach 2:
The patent performs preliminary organization of measurement data into structured formats with metadata describing the spherical coordinate system, elevation-azimuth relationships, and frequency-domain characteristics. This preliminary structuring enables efficient retrieval and processing during audio rendering, reducing real-time computational load.
3Reliability
If HR filters are stored in full detail, then rendering quality is maintained, but memory consumption increases
Solution Approach 1:
The patent extracts only the essential frequency-domain characteristics of HR filters needed for spatial audio rendering, storing them in compact spectral representations rather than full time-domain impulse responses. This extraction maintains the critical acoustic information for spatial perception while removing redundant data, significantly reducing memory requirements.
Solution Approach 2:
The patent transforms HR filter data from the time dimension to the frequency dimension using spectral representations. This dimensional transformation allows for more compact storage of acoustic characteristics while preserving the information needed for accurate spatial rendering, as frequency-domain data requires less memory than equivalent time-domain data.
Data Source
AI summary
A method for generating a head-related (HR) filter for audio rendering is provided. The method comprises generating HR filter model data which indicates an HR filter model, and based on the generated HR filter model data, (i) sampling one or more basis functions and (ii) generating first basis function shape data and shape metadata. The method further comprises providing the generated first basis function shape data and the shape metadata for storing in one or more storage mediums.