ThreeBandToneControlFract32

Overview

Three band equalizer

Discussion

This module implements a three band tone control fixed point module. Low shelf filter is used for low frequency band with normalised gain with respect to mid band gain. Similarly for high frequency band high shelf filter is used with normalised gain with respect to mid gain. Finally scale smoothely the entire signal with mid band gain.

Module Pack

Standard

ClassID

classID = 210

Type Definition

typedef struct _ModuleThreeBandToneControlFract32
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
FLOAT32 smoothingTime;                        // Time constant of the smoothing process
FLOAT32 lowFreq;                              // Low band center frequency, in Hz
FLOAT32 midFreq;                              // Mid band center frequency, in Hz
FLOAT32 highFreq;                             // High band center frequency, in Hz
FLOAT32 lowGain;                              // Low band gain, in dB
FLOAT32 midGain;                              // Mid band gain, in dB
FLOAT32 highGain;                             // High band gain, in dB
INT32 headRoomBits;                           // Head room bits. This prevents internal clipping in the filter stages
INT32 postShift;                              // postShift controls the headroom within the fixed-point filtering
FLOAT32 twoPowMinusPostShift;                 // Two power -postShift value
INT32 filterUpdateActive;                     // Boolean that is set when updating coefficients
fract32 smoothingCoeff;                       // Smoothing coefficient for the filter coefficients
fract32 midTargetGain;                        // Target gain of the mid frequency gain
fract32 midCurrentGain;                       // Current gain of the mid frequency gain
fract32 midSmoothingCoeff;                    // Sample-by-sample smoothing coefficient of the mid frequency gain
fract32* lowerTargetCoeffs;                   // Target coefficients for the low frequency shelf
fract32* lowerCurrentCoeffs;                  // Current coefficients for the low frequency shelf
fract32* lowerState;                          // State variables for the low frequency shelf
fract32* upperTargetCoeffs;                   // Target coefficients for the high frequency shelf
fract32* upperCurrentCoeffs;                  // Current coefficients for the high frequency shelf
fract32* upperState;                          // State variables for the high frequency shelf
} ModuleThreeBandToneControlFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default Value	Range	Units
smoothingTime	float	parameter	0	20	0:1000	msec
lowFreq	float	parameter	0	60	30:200	Hz
midFreq	float	parameter	0	600	200:4000	Hz
highFreq	float	parameter	0	6000	4000:20000	Hz
lowGain	float	parameter	0	0	-12:12	dB
midGain	float	parameter	0	0	-12:12	dB
highGain	float	parameter	0	0	-12:12	dB
headRoomBits	int	parameter	1	2	Unrestricted
postShift	int	parameter	1	5	Unrestricted
twoPowMinusPostShift	float	parameter	1	0.03125	Unrestricted
filterUpdateActive	int	parameter	1	1	Unrestricted
smoothingCoeff	fract32	parameter	1	0.032784	Unrestricted
midTargetGain	fract32	parameter	1	0.03125	Unrestricted
midCurrentGain	fract32	parameter	1	0.03125	Unrestricted
midSmoothingCoeff	fract32	parameter	1	0.0010412	Unrestricted
lowerTargetCoeffs	fract32*	parameter	1	[5 x 1]	Unrestricted
lowerCurrentCoeffs	fract32*	parameter	1	[5 x 1]	Unrestricted
lowerState	fract32*	state	1	[4 x 1]	Unrestricted
upperTargetCoeffs	fract32*	parameter	1	[5 x 1]	Unrestricted
upperCurrentCoeffs	fract32*	parameter	1	[5 x 1]	Unrestricted
upperState	fract32*	state	1	[4 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

Scratch Pins


Channel Count	1
Block size	32
Sample rate	48000

Matlab Usage

File Name: three_band_tone_control_fract32_module.m 
 M=three_band_tone_control_fract32_module(NAME) 
 Implements a three band tone control module. 
 Arguments: 
    NAME - name of the module.