MeterFract32

Overview

Peak and RMS meter module

Discussion

The MeterFract32 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
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

In meterTypes 0 to 3, the peak attack and release are performed on a sample-by-sample basis in the envelope follower. In meterTypes 16 to 19, 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 _ModuleMeterFract32
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 meterType;                              // Operating module 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
    fract32 attackCoeffFract32;                   // Internal coefficient that realizes the attack time
    fract32 releaseCoeffFract32;                  // Internal coefficient that realizes the release time
    fract32* value;                               // Array of meter output values, one per channel
} ModuleMeterFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
meterType	int	parameter	0	18	0:3, 16:19
attackTime	float	derived	1	65	0:1000	msec
releaseTime	float	derived	1	65	0:10000	msec
attackCoeffFract32	fract32	derived	1	0.02336	Unrestricted
releaseCoeffFract32	fract32	derived	1	0.02336	Unrestricted
value	fract32*	state	0	[1 x 1]	-60:10

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

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: meter_fract32_module.m

CODE

 M=meter_fract32_module(NAME)
 Creates a meter module for usein the Audio Weaver environment.
 The module has a single multi-channel input pin.  Arguments:
    NAME - name of the module.