Augmented Ambisonics Encoding for High-Resolution FOA Playback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ambisonics recordings, particularly those of lower orders like first-order ambisonics (FOA), suffer from low spatial resolution during playback, leading to blurry sound sources, while capturing higher-order ambisonics requires a large number of channels that are computationally and mechanically impractical.
Innovation Solution
A method and system that augments lower-order ambisonics, such as FOA, by performing parametric spatial audio processing to determine filters and VBAP gains, spatially rendering audio signals, and encoding them into a higher-order ambisonics format, such as 2nd or 3rd order, using a virtual loudspeaker array with even distribution on a sphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of channels is increased to improve spatial resolution, then the spatial resolution is improved, but the device complexity and mechanical impracticality increase
Solution Approach 1:
The patent applies preliminary action by performing parametric analysis on the audio signals during the encoding phase to extract spatial parameters (direction of arrival, diffuseness, inter-channel level differences, inter-channel time differences, and inter-channel coherence). These parameters are then used to determine appropriate filters and VBAP gains that will achieve the desired spatial resolution at playback without requiring a high channel count during capture. This preliminary extraction and storage of spatial information enables later high-resolution rendering from a low-channel recording.
Solution Approach 2:
The patent applies parameter changes by transforming the audio signals from the time domain to the frequency domain using Fourier transforms, and then performing parametric analysis to extract spatial parameters. The system changes the representation parameters from raw channel signals to extracted spatial characteristics (DoA, diffuseness, ICLD, ICTD, ICC), which can then be used to synthesize higher-order ambisonics signals. This parameter transformation enables spatial resolution enhancement without increasing the original channel count.
2Measurement precision
If the number of channels is increased to improve spatial resolution, then the spatial resolution is improved, but the computational impracticality increases
Solution Approach 1:
The patent applies the extraction principle by separating and extracting specific spatial parameters (direction of arrival, diffuseness, inter-channel level differences, inter-channel time differences, and inter-channel coherence) from the multi-channel audio signals. Instead of processing all channel signals directly for spatial rendering, the system extracts these key parameters that capture the essential spatial information. This extraction reduces the computational burden by focusing only on the most important spatial characteristics needed for high-resolution playback.
Solution Approach 2:
The patent uses an intermediary approach by introducing parametric analysis as an intermediate processing step between the original multi-channel signals and the final spatial rendering. The extracted spatial parameters serve as intermediaries that bridge the gap between low-channel capture and high-resolution playback. These intermediate parameters enable the system to achieve higher-order ambisonics representation without directly processing high-channel signals throughout the entire system, thus reducing overall computational complexity.
3Measurement precision
If filters are determined through parametric analysis to enhance spatial resolution, then the spatial resolution is improved, but the processing time increases
Solution Approach 1:
The patent applies preliminary action by performing the computationally intensive parametric analysis and filter determination during the audio encoding phase, when the audio content is being recorded or processed initially. The extracted spatial parameters and determined filters are then stored and reused during playback. This shifts the processing time burden to the encoding phase, allowing for faster, real-time playback without repeating the heavy computations, thus resolving the time penalty for high spatial resolution.
Data Source
AI summary
A method that includes receiving audio content in a first-order ambisonics (FOA) format that includes a first plurality of audio signals, producing a plurality of spatially rendered audio signals by spatially rendering the first plurality of audio signals according to a layout of a virtual loudspeaker array, determining one or more filters by performing a parametric analysis upon at least one of the first plurality of audio signals, filtering at least one of the plurality of spatially rendered audio signals using the one or more filters; and producing a second plurality of audio signals in a higher-order ambisonics (HOA) format based on the plurality of spatially rendered audio signals.