(8.D.1.2) STSMR
Overview
ST Sound Meter
Discussion
The SoundMeter converts a fract32 PCM signal into a logarithmic scale. Pre-filtering is possible with three different configurations (DC removal, A-weighting and C-weighting). Logarithmic conversion is then performed. A smoothing filter allows to average the log values with a configurable time constant. It supports three different sample rates, mono or stereo signal, with a maximum input frame size of 480 stereo samples.
Supported sample rates are: 8, 16, or 48 kHz.
The inspector shows the left and right levels in dB with a useful range of 0 to -90 dB.
Type Definition
typedef struct _ModuleSTSMR
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 enable; // Block enable
INT32 averaging_time; // Smoothing time (0 - 10000) Ms
INT32 filter_type; // Filter type (none, A weight, C weight, DC removal)
FLOAT32 mean_level_left; // Measured left channel level
FLOAT32 mean_level_right; // Measured right channel level
INT32 nAPIResult; // Return status for last call into the ST API
void * pGlobals; // Points to the global variables structure
} ModuleSTSMRClass;
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
enable | int | parameter | 0 | 1 | 0:1:1 | Â |
averaging_time | int | parameter | 0 | 1000 | 0:1:10000 | msec |
filter_type | int | parameter | 0 | 0 | Unrestricted | Â |
mean_level_left | float | state | 0 | 0 | -90:0 | Â |
mean_level_right | float | state | 0 | 0 | -90:0 | Â |
nAPIResult | int | state | 1 | 1 | Unrestricted | Â |
pGlobals | void * | const | 1 | Â | Unrestricted | Â |
Pins
Input Pins
Name: in
Description: audio input
Data type: fract32
Channel range: 1, 2
Block size range: 96:480
Sample rate range: 8000, 16000, 48000
Complex support: Real
Output Pins
Name: out
Description: audio output
Data type: fract32
Scratch Pins
Channel count: 1
Block size: 96
Sample rate: 8000
MATLAB Usage
File Name: st_smr_module.m
M = st_smr_module(NAME)
Audio Weaver wrapper for the ST Sound Meter module. Arguments:
NAME - name of the module.
Copyright (c) 2017 DSP Concepts, Inc. All Rights Reserved.
Author: Chris Perry
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