BiquadV2Fract32

Overview

2nd order IIR filter

Discussion

Second order 5 multiply recursive filter with algorithm precision selectable. Precision type 0 uses 24x24 with 56-bit accumulator, 1 uses 32x32 with 32-bit accumulator, 2 uses 32x32 with 64-bit accumulator and 3 uses 24x24 with 24-bit accumulator. 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. The module implements the difference equation:

\(y[n]=b_0x[n]+b_1x[n-1]+b_2x[n-2]-a_1y[n-1]-a_2y[n-2].\)

Module Pack

Standard

ClassID

classID = 137

Type Definition

typedef struct _ModuleBiquadV2Fract32
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
INT32 precisionType;                          // Boolean value that determines whether all channels are summed to form a single output.
INT32 updateActive;                           // Specifies whether the filter coefficients are updating (=1) or fixed (=0).
INT32 postShift;                              // Number of bits to shift
INT32 bShift;                                 // Number of bits to shift of Numerator coefficients
INT32 currentBShift;                          // Current post shift of Numerator coefficients
INT32 aShift;                                 // Number of bits to shift of Denominator coefficients
INT32 currentAShift;                          // Current post shift of Denominator coefficients
FLOAT32* coeffs;                              // coefficients
fract32* coeffsFract32;                       // coefficients in Fract32
fract32* state;                               // State variables.  6 per channel.
fract32* currentCoeffsFract32;                // Current coefficients in Fract32
} ModuleBiquadV2Fract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default Value	Range
precisionType	int	const	0	0	Unrestricted
updateActive	int	state	0	1	0:1
postShift	int	parameter	1	2	Unrestricted
bShift	int	derived	1	1	Unrestricted
currentBShift	int	state	1	3	Unrestricted
aShift	int	derived	1	1	Unrestricted
currentAShift	int	state	1	2	Unrestricted
coeffs	float*	parameter	0	[5 x 1]	Unrestricted
coeffsFract32	fract32*	derived	0	[5 x 1]	Unrestricted
state	fract32*	state	1	[6 x 1]	Unrestricted
currentCoeffsFract32	fract32*	state	0	[5 x 1]	Unrestricted

Pins

Input Pins


Name	in
Description	audio input
Data type	fract32
Channel range	Unrestricted
Block size range	Unrestricted
Sample rate range	Unrestricted
Complex support	Real

Output Pins


Name	out
Description	audio output
Data Type	fract32

Matlab Usage

File Name: biquad_v2_fract32_module.m 
 M=biquad_v2_fract32_module(NAME, TYPE) 
 Creates a second order IIR filter Fract32 (biquad) for use with the Audio 
 Weaver.  Arguments: 
     NAME - name of the module. 
     TYPE - Precision type. 0 - 24x24 with 56-bit Acc 
                            1 - 32x32 with 32-bit Acc 
                            2 - 32x32 with 64-bit Acc 
                            3 - 24x24 with 24-bit Acc