Channel-Based 3D Audio to HOA Conversion via Primary Ambient Decomposition
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Solution Overview
Problem
Converting channel-based 3D audio signals to HOA audio signals is challenging due to the mix of directional and ambient sound signals, requiring a method to extract directional and ambient information effectively for HOA encoding.
Innovation Solution
The method employs primary ambient decomposition (PAD) techniques, triangulating channel positions to form non-overlapping triangles, successively decomposing triplets into directional and ambient signals, deriving directional information, and encoding these signals using HOA encoding methods based on channel positions, then superimposing coefficients to obtain HOA coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If audio channels are directly encoded to HOA using channel positions as directional information, then conversion is simple, but the mix of directional and ambient signals results in poor spatial immersion and source localization
Solution Approach 1:
The audio signal is segmented into directional and ambient components through primary ambient decomposition. The directional signal is extracted by computing the difference between the maximum and minimum channel amplitudes, while the ambient signal is obtained by subtracting the directional component from the total signal. This segmentation allows each component to be encoded separately with appropriate HOA coefficients, resolving the contradiction between conversion simplicity and spatial quality.
Solution Approach 2:
The directional information is extracted from the mixed audio channels by identifying and isolating the directional component through amplitude difference analysis. The extraction process separates the directional signal (containing source localization information) from the ambient signal (containing spatial immersion information), enabling independent optimization of both components during HOA encoding.
2Reliability
If primary ambient decomposition is applied to extract directional signals, then spatial immersion and source localization are enhanced, but computational complexity increases
Solution Approach 1:
Instead of performing complete signal decomposition and analysis, the method applies partial action by using simple amplitude difference calculations to extract directional information. The directional signal is obtained through the difference between maximum and minimum channel amplitudes, which is computationally lightweight compared to full decomposition methods, thus reducing computational complexity while maintaining spatial quality.
Solution Approach 2:
The method changes the parameter space from complex signal decomposition to simple amplitude-based extraction. By transforming the problem into the amplitude domain and using threshold-based separation, the computational burden is significantly reduced while still achieving effective directional and ambient signal separation for HOA encoding.
3Measurement precision
If audio channels are processed to separate directional and ambient signals, then source localization is improved, but processing time increases
Solution Approach 1:
The method skips complex decomposition steps and rushes through the essential extraction process by using direct amplitude difference calculations. The directional signal extraction is performed through simple comparisons of channel amplitudes rather than iterative decomposition, significantly reducing processing time while maintaining source localization precision through the preserved amplitude difference information.
Data Source
AI summary
A system for converting a channel-based 3D audio signal to a higher-order Ambisonics HOA audio signal, the channel-based 3D audio signal is transformed from time domain to frequency domain. A primary ambient decomposition is carried out for three-channel triplets of blocks of the domain channel-based 3D audio signal, wherein directional signals and ambient signals are provided for each triplet. From the directional signals directional information of a total directional signal for each triple is derived. That total directional signal is HOA encoded according to the derived directions, and ambient signals are HOA encoded according to channel positions. The HOA coefficients of the HOA encoded directional signal and the HOA coefficients of the HOA encoded ambient signal are superimposed in order to obtain a HOA coefficients signal for the channel-based 3D audio signal, followed by a transformation into time domain.