Multi-Channel Parametric Equalization for Inter-Channel Phase Tuning
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Solution Overview
Problem
Parametric biquadratic all-pass filters are difficult to intuitively tune for achieving desired inter-channel phase-differences, especially in multi-channel audio systems, due to the need for co-dependent adjustments of multiple filters, making manual tuning time-consuming and inefficient.
Innovation Solution
A method and system for determining filter coefficients using a common set of filter design parameters including phase difference and frequency information, allowing simultaneous control of multiple audio filters, thereby simplifying the tuning process by focusing on inter-channel phase differences rather than absolute phase shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual tuning of parametric biquadratic all-pass filters is performed to achieve desired inter-channel phase-differences, then the phase response can be adjusted, but the tuning process becomes very time consuming and complex
Solution Approach 1:
The patent transforms the filter design parameters from traditional magnitude-response parameters (gain, center frequency, Q) to phase-difference parameters (inter-channel phase-difference, center frequency, Q). This parameter transformation allows direct control of phase-difference characteristics, eliminating the need for time-consuming manual tuning while maintaining precision in achieving desired inter-channel phase responses
Solution Approach 2:
The patent introduces an intermediary computational process that automatically calculates and adjusts filter coefficients based on desired phase-difference specifications. This intermediary system acts as a mediator between the user's phase-difference requirements and the actual filter implementation, automating the tuning process and reducing both time and complexity
2Adaptability or versatility
If multiple filters per channel are used to achieve detailed desired response, then the phase control capability is improved, but the tuning complexity increases significantly
Solution Approach 1:
The patent creates a universal parametric framework that can control both single filters and multiple filters per channel using the same phase-difference parameterization approach. This multi-functional system handles different filter configurations uniformly, maintaining adaptability for detailed phase control while reducing tuning complexity through consistent parameter interpretation across all filter types and configurations
3Ease of operation
If traditional parametric control is used for all-pass filters, then the filter response can be adjusted, but intuitive tuning for desired phase-difference is difficult
Solution Approach 1:
The patent changes the parameterization from magnitude-response parameters to phase-difference parameters, making the tuning process intuitive by directly linking control parameters to the desired phase-difference outcome. This allows operators to specify exact phase-difference values without needing to understand complex filter interactions, while the system ensures accurate implementation of these specifications
Data Source
AI summary
There is provided a method of determining filter coefficients for an audio filter system including a number, N≥2, of filter paths for enabling processing of N audio channels, one filter path per channel, wherein each filter path includes at least one audio filter for performing the processing of the corresponding channel. The method includes providing a common set of filter design parameters for a pair of audio filters belonging to different filter paths, including phase difference information representing an inter-channel phase difference and frequency information representing a frequency value as filter design parameters; and determining filter coefficients for the pair of audio filters at least partly based on the common set of filter design parameters.