AudioWeighting

Overview

Standard audio weighting filters

Discussion

Implements standard weighting filters used in audio. The module operates on multiple channels and internally uses a BiquadCascade modoule. The .weightingType variable specifies what type of filter is implemented.
Allowable values are:

0 = Flat

1 = A weighting

2 = B weighting

3 = C weighting

4 = D weighting

5 = ITU468

6 = LeqM

7 = ITU1770

When changing filter types, the audio output is muted, the filter's state variables are set to zero and then the coefficients are updated. Once the coefficients are changed, the audio is unmuted.

Module Pack

Advanced

ClassID

classID = 1214

Type Definition

typedef struct _ModuleAudioWeighting
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
INT32 weightingType;                          // Selects weighting type
INT32 numStages;                              // Number of stages in the IIR filter
FLOAT32* coeffs;                              // Array of precomputed filter coefficients for the specified sampling rate
awe_modBiquadCascadeInstance *filt; // Cascade of second order Biquad filtersawe_modMuteUnmuteInstance *mute; // Mutes and unmutes to hide artifacts} ModuleAudioWeightingClass;

Variables

Properties

Name	Type	Usage	isHidden	Default Value	Range
weightingType	int	parameter	0	0	0:7
numStages	int	parameter	1	4	Unrestricted
coeffs	float*	parameter	1	[160 x 1]	Unrestricted

Pins

Input Pins


Name	in
Description	Audio Input
Data type	float
Channel range	Unrestricted
Block size range	Unrestricted
Sample rate range	Unrestricted
Complex support	Real

Output Pins


Name	out
Description	Audio output
Data Type	float

Scratch Pins


Channel Count	1
Block size	32
Sample rate	48000


Channel Count	1
Block size	32
Sample rate	48000

Matlab Usage

File Name: weighting_module.m 
 SYS = weighting_module(NAME) 
 Creates a module which implements standard audio frequency weightings: 
 A, B, C, D, ITU 468, and Leq M.  Arguments: 
    NAME - name of the module. 
 The module stores all of the various filter coefficients in an internal 
 array and you can switch between filter types at run-time.  Internally, 
 the module uses a Biquad cascade together with a mute/unmute module to  
 hide switching transients.