Overview
RMS detector with built-in smoothing
Discussion
This module calculates the smoothed RMS value of the input signal on a block-by-block basis. The input pin can have an arbitrary number of interleaved channels and the RMS calculation occurs over all channels. The output pin has a single channel and a blockSize of 1.
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The module also exposes some of the computed signals as state variables. The variable filteredValue holds the output of the module (the smoothed RMS value). The variable instantaneousValue holds the square root of the average energy in the block; no smoothing.
Type Definition
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typedef struct _ModuleRMS
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
FLOAT32 smoothingTime; // Time interval over which to smooth the measurement.
FLOAT32 instantaneousValue; // Instantaneous (unsmoothed) output value.
FLOAT32 filteredValue; // Smoothed output value.
FLOAT32 a1; // a1 coefficient of 1st order smoothing filter.
FLOAT32 b0; // b0 coefficient of 1st order smoothing filter.
FLOAT32 b1; // b1 coefficient of 1st order smoothing filter.
FLOAT32 xNm1; // Delayed input sample.
FLOAT32 yNm1; // Delayed output sample.
} ModuleRMSClass; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
smoothingTime | float | parameter | 0 | 1000 | 0:10000 | msec |
instantaneousValue | float | state | 0 | 0 | -60:10 | |
filteredValue | float | state | 0 | 0 | -60:10 | |
a1 | float | derived | 1 | -0.9958 | Unrestricted | |
b0 | float | derived | 1 | 0.00418 | Unrestricted | |
b1 | float | derived | 1 | 0 | Unrestricted | |
xNm1 | float | state | 1 | 0 | Unrestricted | |
yNm1 | float | state | 1 | 0 | Unrestricted |
Pins
Input Pins
Name: in1
Description: Audio input
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Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: Filtered RMS output
Data type: float
MATLAB Usage
File Name: rms_module.m
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M=rms_module(NAME, NUMIN)
RMS detector with built-in smoothing. The module accepts multiple input
signals and computes a control signal which reprsents the smoothed
RMS value.
Arguments:
NAME - name of the module.
NUMIN - number of input pins. |