Meter

Overview

Peak and RMS meter module

Discussion

The Meter module provides a flexible level meter that can operate in several modes. The module has a single multichannel input and separately meters each channel. The meter can be configured to conform to IEC 60280-10 (peak meters) and IEC 60280-17 (VU Meter) specifications. The meterType parameter is used to configure the module as follows.

meterType	Description	Attack Time (msec)	Release Time (msec)	Comments
0	FastPeakSample	5	1087	Peak meter: IEC 60280-10 "fast mode"
1	SlowPeakSample	10	1450	Peak meter: IEC 60280-10 "slow mode"
2	VUMeterSample	65	65	IEC 60280-17 standard "VU meter"
3	CustomSample	user	user	Set the attackTime and releaseTime from a Matlab script
4	InstantSample	0	0	Instantaneous (attack and release times of 0 msec). The meter value equals the last value in each block.
16	FastPeakBlock	5	1087	Computationally efficient peak meter: IEC 60280-10 "fast mode"
17	SlowPeakBlock	10	1450	Computationally efficient peak meter: IEC 60280-10 "slow mode"
18	VUMeterBlock	65	65	Computationally efficient IEC 60280-17 standard "VU meter"
19	CustomBlock	user	user	Computationally efficient custom meter. Set the attackTime and releaseTime from a Matlab script
20	InstantBlock	0	0	Computationally efficient instantaneous meter (attack and release times of 0 msec). The max abs value of each block is returned without time constants.

In meterTypes 0 to 4, the peak attack and release are performed on a sample-by-sample basis in the envelope follower. In meterTypes 16 to 20, the peak absolute value for the entire input block is found and this one value is passed through the envelope follower.

Type Definition

CODE

typedef struct _ModuleMeter
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 meterType;                              // Operating mode of the meter. Selects between peak and RMS calculations. See the discussion section for more details.
    FLOAT32 attackTime;                           // Attack time of the meter. Specifies how quickly the meter value rises.
    FLOAT32 releaseTime;                          // Release time of the meter. Specifies how quickly the meter decays.
    FLOAT32 attackCoeff;                          // Internal coefficient that realizes the attack time.
    FLOAT32 releaseCoeff;                         // Internal coefficient that realizes the release time.
    FLOAT32* value;                               // Array of meter output values, one per channel.
} ModuleMeterClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
meterType	int	parameter	0	18	Unrestricted
attackTime	float	derived	1	65	0:1000	msec
releaseTime	float	derived	1	65	0:10000	msec
attackCoeff	float	derived	1	0.02336	Unrestricted
releaseCoeff	float	derived	1	0.02336	Unrestricted
value	float*	state	0	[1 x 1]	-60:10	linear

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

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: meter_module.m

CODE

 M=meter_module(NAME)
 Creates a meter module for use in the Audio Weaver environment.
 The module has a single multichannel input pin.  

 Arguments:
    NAME - name of the module.