(8.D.2.6) ScalerNSymmetricFading
Overview
General purpose scaler with separate gains per channel
Discussion
Scaler (or gain) module for floating-point signals. Compared to the general purpose scaler, this module takes equal time for fadein and fadeout as decided by fadingTime. This module has a single gain (masterGain) which is applied all channels plus a separate per channel gain (trimGain). For each channel, masterGain and trimGain[n] is combined to form the target gain value.
The gains are intrepreted as either linear or dB values based on the isDB module variable. By default, isDB=1 and the gains are treated as dB values. If you set isDB=0 then the gains are treated as linear values. When in dB, targetGain = masterGain + trimGain[n]. When in linear mode, targetGain = masterGain * trimGain[n].
The module can also switch between smoothed and unsmoothed gain changes. You enable smoothing by setting the parameter fadingTime to a non-zero value. If fadingTime=0 then no smoothing is performed. fadingTime is the time in which the target gain is achieved. The module is slightly more efficient when no smoothing occurs.
The module argument NUMCHANNELS sets the initial number of channels. This allows you to configure the module for the proper number of channels before the system is built. After the system is built, NUMCHANNELS is no longer used and the number of channels is determined from the input wire. The module can also handle complex data no smoothing is performed and the gain value is applied to both the real and imaginary parts.
Type Definition
typedef struct _ModuleScalerNSymmetricFading
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
FLOAT32 masterGain; // Overall gain to apply. Min linear gain is clamped to 0.
FLOAT32 fadingTime; // Time in which the target gain has to be reached (0 = unsmoothed).
INT32 isDB; // Selects between linear (=0) and dB (=1) operation
FLOAT32* trimGain; // Array of trim gains, one per channel
FLOAT32* targetGain; // Computed target gains in linear units
FLOAT32* currentGain; // Instanteous gains. These ramp towards targetGain
FLOAT32* factor; // The factor to be multiplied for implementing the exponential ramp up or ramp down
INT32* numSamples; // Number of samples over which smoothing has to be applied
FLOAT32* prevGain; // Previous gains
} ModuleScalerNSymmetricFadingClass;
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
masterGain | float | parameter | 0 | 0 | -24:24 | dB |
fadingTime | float | parameter | 0 | 10 | 0:1000 | msec |
isDB | int | parameter | 0 | 1 | 0:1 | Â |
trimGain | float* | parameter | 0 | [1 x 1] | -24:24 | dB |
targetGain | float* | derived | 1 | [1 x 1] | Unrestricted | Â |
currentGain | float* | state | 1 | [1 x 1] | Unrestricted | Â |
factor | float* | derived | 1 | [1 x 1] | Unrestricted | Â |
numSamples | int* | derived | 1 | [1 x 1] | Unrestricted | Â |
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 and Complex
Output Pins
Name: out
Description: audio output
Data type: float
MATLAB Usage
File Name: scalern_symmetric_fading_module.m
M = scalern_symmetric_fading_module(NAME, NUMCHANNELS)
Scaler module with a separate gain per channel.
Compared to the general purpose scaler, this scaler takes equal time for fadeIn or FadeOut.
The module can be configured for linear or dB operation as well as
smoothed and unsmoothed gain changes. Arguments:
NAME - name of the module.
NUMCHANNELS - default number of channels. Default = 1. This is
used to draw the initial inspector. The actual number of
channels processed by the module is determined by pin
propagation.
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