Ambisonic Decoder Filters from Combined HRTF Impulse Responses
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Solution Overview
Problem
Existing methods for binaural rendering of Ambisonic audio signals are computationally expensive and inefficient, requiring numerous Ambisonic decoder filters to be computed and stored due to the individual nature of Head Related Transfer Functions (HRTFs) and the lossy format of Ambisonics, leading to impractical processing and memory demands.
Innovation Solution
A method for generating Ambisonic decoder filters by combining HRTF impulse response sets to create a combined Ambisonically rendered IR set, which is then encoded into the Ambisonic domain, allowing efficient computation and storage of filters for various HRTF combinations, reducing the need for extensive storage of individual filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iterative optimization methods are used to binauralise Ambisonic signals, then spatialisation accuracy is improved, but computational complexity and processing time increase significantly
Solution Approach 1:
The patent pre-computes Ambisonic decoder filters for a set of representative HRTFs and stores them in a database. During runtime, the system retrieves pre-computed filters matching the user's HRTF characteristics rather than performing iterative optimization, thus achieving accurate spatialisation without real-time computational complexity.
Solution Approach 2:
The patent segments the HRTF database into multiple representative sets and pre-computes decoder filters for each segment. This allows the system to quickly retrieve appropriate pre-computed filters based on user characteristics, avoiding the need for full iterative optimization while maintaining spatialisation accuracy.
2Measurement precision
If many optimised Ambisonic decoder filters are computed and stored for different HRTFs, then binaural rendering accuracy is improved, but memory storage requirements become impractical
Solution Approach 1:
The patent creates a set of representative HRTFs that can serve multiple users with similar anatomical characteristics. Each representative HRTF has pre-computed decoder filters that work for multiple individuals, reducing the total number of filters needed while maintaining accuracy for diverse user groups.
Solution Approach 2:
The system pre-computes and stores decoder filters for a limited set of representative HRTFs during system initialization or offline processing. This preliminary action eliminates the need for real-time computation and reduces memory requirements by storing only essential pre-computed filters rather than filters for every possible HRTF variation.
3Adaptability or versatility
If iterative optimization methods are performed multiple times for different HRTF combinations, then adaptability to individual users is improved, but processing time becomes impractical for large databases
Solution Approach 1:
The patent performs the computationally intensive iterative optimization process in advance for a set of representative HRTFs and stores the results. When a user requests binaural rendering, the system quickly retrieves the pre-computed filters matching the user's HRTF characteristics, achieving individualized adaptation without real-time processing delays.
Solution Approach 2:
The HRTF database is segmented into representative groups, and optimization is performed once for each segment. This segmentation allows the system to cover diverse user characteristics while minimizing total processing time, as each segment requires only a single optimization pass rather than repeated optimization for every individual case.
Data Source
AI summary
A computer implemented method of generating an Ambisonic decoder filter for binaural rendering of Ambisonic signals according to a combination of head-related transfer functions (HRTFs), the method comprising: obtaining Ambisonic decoder filters for each of a plurality of HRTF impulse response (IR) sets, each HRTF IR set comprising a plurality of IRs, each IR associated with a different sound source direction; combining each Ambisonic decoder filter with a set of impulses rendered in the Ambisonic domain and associated with different sound source directions to generate a plurality of Ambisonically rendered IR sets; combining at least one of the Ambisonically rendered IR sets with at least one other of the Ambisonically rendered IR sets to generate a combined Ambisonically rendered IR set; and encoding the combined Ambisonically rendered IR set into the Ambisonic domain to generate an Ambisonic decoder filter adapted to binauralise Ambisonic signals according to the combination of HRTFs from which the combined Ambisonically rendered IR set was generated.