Overview
Subband SOF detector
Discussion
This module implements a general purpose second order filter that operates on subband data and that is capable of realizing many different filter types. The function can operate on real or complex data. For complex data, the function filters the real and imaginary components separately.
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filterType=22, 2nd order Butterworth high pass filter with variable Q. [freq, Q].
Type Definition
Code Block |
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typedef struct _ModuleSbSOF { ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure INT32 filterType; // Selects the type of filter that is implemented by the module: Bypass=0, Gain=1, Butter1stLPF=2, Butter2ndLPF=3, Butter1stHPF=4, Butter2ndHPF=5, Allpass1st=6, Allpass2nd=7, Shelf2ndLow=8, Shelf2ndLowQ=9, Shelf2ndHigh=10, Shelf2ndHighQ=11, PeakEQ=12, Notch=13, Bandpass=14, Bessel1stLPF=15, Bessel1stHPF=16, AsymShelf1stLow=17, AsymShelf1stHigh=18, SymShelf1stLow=19, SymShelf1stHigh=20, VariableQLPF=21, VariableQHPF=22. FLOAT32 freq; // Cutoff frequency of the filter, in Hz. FLOAT32 gain; // Amount of boost or cut to apply, in dB if applicable. FLOAT32 Q; // Specifies the Q of the filter, if applicable. FLOAT32 smoothingTime; // Time constant of the smoothing process. INT32 updateActive; // Specifies whether the filter coefficients are updating (=1) or fixed (=0). FLOAT32 b0; // Desired first numerator coefficient. FLOAT32 b1; // Desired second numerator coefficient. FLOAT32 b2; // Desired third numerator coefficient. FLOAT32 a1; // Desired second denominator coefficient. FLOAT32 a2; // Desired third denominator coefficient. FLOAT32 current_b0; // Instantaneous first numerator coefficient. FLOAT32 current_b1; // Instantaneous second numerator coefficient. FLOAT32 current_b2; // Instantaneous third numerator coefficient. FLOAT32 current_a1; // Instantaneous second denominator coefficient. FLOAT32 current_a2; // Instantaneous third denominator coefficient. FLOAT32 smoothingCoeff; // Smoothing coefficient. This is computed based on the smoothingTime, sample rate, and block size of the module. FLOAT32* state; // State variables. 2 per channel. } ModuleSbSOFClass; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
filterType | int | parameter | 0 | 0 | 0:22 | |
freq | float | parameter | 0 | 250 | 1:20000 | Hz |
gain | float | parameter | 0 | 6 | -24:24 | dB |
Q | float | parameter | 0 | 1 | -20:20 | |
smoothingTime | float | parameter | 0 | 10 | 0:1000 | msec |
updateActive | int | parameter | 1 | 1 | 0:1 | |
b0 | float | derived | 1 | 1 | Unrestricted | |
b1 | float | derived | 1 | 0 | Unrestricted | |
b2 | float | derived | 1 | 0 | Unrestricted | |
a1 | float | derived | 1 | 0 | Unrestricted | |
a2 | float | derived | 1 | 0 | Unrestricted | |
current_b0 | float | state | 1 | 1 | Unrestricted | |
current_b1 | float | state | 1 | 0 | Unrestricted | |
current_b2 | float | state | 1 | 0 | Unrestricted | |
current_a1 | float | state | 1 | 0 | Unrestricted | |
current_a2 | float | state | 1 | 0 | Unrestricted | |
smoothingCoeff | float | derived | 1 | 0.06449 | Unrestricted | |
state | float* | state | 1 | [64 x 1] | Unrestricted |
Pins
Input Pins
Name: in
Description: audio input
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Complex support: Real and Complex
Output Pins
Name: out
Description: audio output
Data type: float
MATLAB Usage
File Name: sb_sof_module.m
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