Audio Format Converter Modulated Decorrelation
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Solution Overview
Problem
Existing methods for upmixing low-resolution multi-channel audio signals to high-resolution Soundfield Formats, such as from 3-channel BF1h to 9-channel BF4h, suffer from excessive correlation between speaker channels and inadequate power distribution, leading to an uncomfortable listening experience with noticeable phase artifacts.
Innovation Solution
The implementation of a Format Converter using Linear Time Invariant (LTI) filters and decorrelators to transform the low-resolution Soundfield Format into a higher-resolution format, specifically by defining an N r -input, N p -output LTI transfer function, and applying modulation functions to reduce correlation while preserving power distribution, thereby enhancing the listening experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing upmixing methods are used to transform low-resolution audio signals to high-resolution Soundfield Formats, then the spatial resolution is improved, but excessive correlation between speaker channels occurs leading to phase artifacts
Solution Approach 1:
The patent introduces decorrelators as intermediary devices between the upmixing process and the speaker channels. These decorrelators process the audio signals to reduce excessive correlation while preserving the spatial resolution benefits of high-resolution Soundfield Formats, thereby eliminating phase artifacts without sacrificing measurement precision
Solution Approach 2:
The patent modifies the correlation parameter of the audio signals by applying decorrelation processing. This changes the statistical properties of the signals between speaker channels, reducing excessive correlation while maintaining the spatial resolution improvement achieved through upmixing to high-resolution formats
2Measurement precision
If existing upmixing methods are used to transform low-resolution audio signals to high-resolution Soundfield Formats, then the spatial resolution is improved, but inadequate power distribution occurs leading to uncomfortable listening experience
Solution Approach 1:
The patent employs feedback mechanisms that monitor the power distribution across speaker channels and adjust the upmixing process accordingly. This feedback loop ensures that power is distributed adequately to all channels while maintaining the spatial resolution benefits of high-resolution Soundfield Formats, preventing the inadequate power distribution that causes uncomfortable listening experiences
3Object-generated harmful factors
If decorrelators are applied to reduce correlation between channels, then phase artifacts are reduced, but the complexity of the audio processing system increases
Solution Approach 1:
The patent segments the audio processing system into distinct functional blocks: upmixing stage, decorrelation stage, and power distribution stage. This segmentation allows the decorrelators to be applied in a targeted manner to specific channels or signal paths, reducing phase artifacts while managing system complexity through modular design rather than requiring complete system redesign
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
Some methods involve receiving an input audio signal that includes N input audio channels, the input audio signal representing a first soundfield format having a first soundfield format resolution, N being an integer ≥ 2. A first decorrelation process may be applied to two or more of the input audio channels to produce a first set of decorrelated channels, the first decorrelation process maintaining an inter-channel correlation of the set of input audio channels. A first modulation process may be applied to the first set of decorrelated channels to produce a first set of decorrelated and modulated output channels. The first set of decorrelated and modulated output channels may be combined with two or more undecorrelated output channels to produce an output audio signal that includes O output audio channels representing a second and relatively higher-resolution soundfield format than the first soundfield format, O being an integer ≥ 3.