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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.

Type Definition

CODE
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

0.03278

Unrestricted

midTargetGain

fract32

parameter

1

0.03125

Unrestricted

midCurrentGain

fract32

parameter

1

0.03125

Unrestricted

midSmoothingCoeff

fract32

parameter

1

0.001041

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

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

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