Overview
2nd order smoothly updating IIR filter
Discussion
Smoothly varying 5 coefficient biquad filter. The module is designed to operate on multiple channels and applies the same coefficients across all channels. The state array is allocated to contain 4*numChannels values. The frequency response of the module is determined by the values of the 5 coefficients, and the coefficients come directly from the MATLAB second order representation. The leading a0 coefficient is not supplied and is assumed to equal 1.0.
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The rate of smoothing is controlled by the .smoothingTime instance variable.
Type Definition
Code Block |
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typedef struct _ModuleBiquadSmoothedFract32 { ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure INT32 updateActive; // Specifies whether the filter coefficients are updating (=1) or fixed (=0) FLOAT32 smoothingTime; // Time constant of the smoothing process fract32 smoothingCoeff; // Smoothing coefficient. This is computed based on the smoothingTime, sample rate, and block size of the module INT32 postShift; // Number of bits to shift INT32 currentPostShift; // Current post shift FLOAT32* coeffs; // Desired coefficients fract32* coeffsFract32; // Desired coefficients in fract32 fract32* current_coeffsFract32; // Instantaneous coefficients fract32* state; // State variables. 4 per channel. } ModuleBiquadSmoothedFract32Class; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
updateActive | int | parameter | 0 | 1 | 0:1 | |
smoothingTime | float | parameter | 0 | 10 | 0:1000 | msec |
smoothingCoeff | fract32 | derived | 1 | 0.06449 | Unrestricted | |
postShift | int | derived | 1 | 1 | Unrestricted | |
currentPostShift | int | state | 1 | 1 | Unrestricted | |
coeffs | float* | parameter | 0 | [5 x 1] | -10:10 | linear |
coeffsFract32 | fract32* | derived | 1 | [5 x 1] | Unrestricted | |
current_coeffsFract32 | fract32* | state | 0 | [5 x 1] | Unrestricted | |
state | fract32* | state | 1 | [4 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: biquad_smoothed_fract32_module.m
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