Overview
Single band of a cascade graphic equalizer with High Precision Biquad fract32 algorithm
Discussion
This module implements a single stage of a graphic equalizer. The stage provides boost or cut over a specified frequency range. A multistage graphic EQ subsystem is constructed as a series cascade of these modules. The multistage graphic EQ is contained within graphic_eq_subsystem.m. This module is typically not used directly. Instead, use the graphic_eq_subsystem.m
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Internally, the filter is implemented as a cascade of High Precision second order biquad sections. These filters are smoothly updating based upon the variable .smoothingTime. Note, some low frequency filters may go unstable if the smoothingTime is too large.
Type Definition
Code Block |
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typedef struct _ModuleGraphicEQBandHpFract32 { ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure FLOAT32 gain; // Gain in the center of the band, in dB FLOAT32 lowerEdge; // Lower frequency edge of the band, in Hz FLOAT32 upperEdge; // Upper frequency edge of the band, in Hz FLOAT32 smoothingTime; // Time constant of the smoothing process. INT32 numStages; // Number of 2nd order stages in the filter INT32 updateActive; // Specifies whether the filter coefficients are updating (=1) or fixed (=0). INT32 bShift; // Number of bits to shift of Numerator coefficients INT32 aShift; // Number of bits to shift of Denominator coefficients fract32 smoothingCoeff; // Smoothing coefficient FLOAT32* coeffs; // Matrix of filter coefficients. The size of the matrix is 5 x numStages. Each column contains the variables for a biquad arranged as [b0; b1; b2; a1; a2]. fract32* coeffsFract32; // Matrix of filter coefficients. The size of the matrix is 5 x numStages. Each column contains the variables for a biquad arranged as [b0; b1; b2; a1; a2]. fract32* currentCoeffsFract32; // Matrix of filter coefficients. The size of the matrix is 5 x numStages. Each column contains the variables for a biquad arranged as [b0; b1; b2; a1; a2]. fract32* state; // State variables. 6 per channel. } ModuleGraphicEQBandHpFract32Class; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
gain | float | parameter | 0 | 0 | -12:12 | dB |
lowerEdge | float | parameter | 0 | 100 | 10:20000 | Hz |
upperEdge | float | parameter | 0 | 500 | 10:20000 | Hz |
smoothingTime | float | parameter | 0 | 50 | 0:1000 | msec |
numStages | int | const | 0 | 4 | Unrestricted | |
updateActive | int | state | 0 | 1 | 0:1 | |
bShift | int | derived | 1 | 4 | Unrestricted | |
aShift | int | derived | 1 | 1 | Unrestricted | |
smoothingCoeff | fract32 | derived | 1 | 0.01324 | Unrestricted | |
coeffs | float* | derived | 1 | [5 x 4] | Unrestricted | |
coeffsFract32 | fract32* | derived | 1 | [5 x 4] | Unrestricted | |
currentCoeffsFract32 | fract32* | state | 1 | [5 x 4] | Unrestricted | |
state | fract32* | state | 1 | [24 x 1] | Unrestricted |
Pins
Input Pins
Name: in
Description: audio input
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Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: audio output
Data type: fract32
MATLAB Usage
File Name: graphic_eq_band_hp_fract32_module.m
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