Overview

Multichannel smooth mute

Discussion

This module is used to hide pops and clicks during transitions. The module smoothly mutes, outputs silence, and then smoothly unmutes. You have full control over mute period, silence period, and unmuting period.

The .trigger variable is used to engage the entire process. Normally trigger=0 and the module passes the input unchanged. When you set trigger=1, then the module goes through the overall mute/silence/unmute cycle.

The module uses a raised cosine window for muting and unmuting. For memory efficiency the module uses a complex recursion to compute the gain profile for the raised cosine.

The constructor argument INITIALSTATE allows you to set the initial state of the trigger variable. By default, INITIALSTATE = 0 meaning that the module starts up unmuted. If you set INITIALSTATE = 1, then the module starts out muted.

Type Definition

typedef struct _ModuleMuteUnmuteFract32
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 trigger;                                // Begins the muting and unmuting process
    FLOAT32 muteTime;                             // Muting time, in msec
    FLOAT32 silenceTime;                          // Duration of the silence period, in msec
    FLOAT32 unmuteTime;                           // Unmuting time, in msec
    INT32 muteTimeSamples;                        // Muting time, in samples
    INT32 silenceTimeSamples;                     // Silence time, in samples
    INT32 unmuteTimeSamples;                      // Unmuting time, in samples
    fract32 muteCoeffR;                           // One of two coefficients used to compute the muting profile
    fract32 muteCoeffI;                           // One of two coefficients used to compute the muting profile
    fract32 unmuteCoeffR;                         // One of two coefficients used to compute the unmuting profile
    fract32 unmuteCoeffI;                         // One of two coefficients used to compute the unmuting profile
    fract32 stateR;                               // One of two state variables which control the ramping profile
    fract32 stateI;                               // One of two state variables which control the ramping profile
    INT32 sampleTime;                             // Counts the samples elapsed in the entire mute/silence/unmute cycle
} ModuleMuteUnmuteFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
trigger	int	state	0	0	0:1
muteTime	float	parameter	0	5	1:1000
silenceTime	float	parameter	0	100	0:10000
unmuteTime	float	parameter	0	50	1:1000
muteTimeSamples	int	derived	1	240	Unrestricted
silenceTimeSamples	int	derived	1	4800	Unrestricted
unmuteTimeSamples	int	derived	1	2400	Unrestricted
muteCoeffR	fract32	derived	1	0.9999	Unrestricted
muteCoeffI	fract32	derived	1	0.01309	Unrestricted
unmuteCoeffR	fract32	derived	1	1	Unrestricted
unmuteCoeffI	fract32	derived	1	0.001309	Unrestricted
stateR	fract32	state	1	0	Unrestricted
stateI	fract32	state	1	0	Unrestricted
sampleTime	int	state	1	0	Unrestricted

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

Output Pins

Name: out

Description: audio output

Data type: fract32

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: mute_unmute_fract32_module.m

 M=mute_unmute_fract32_module(NAME, INITIALSTATE)
 Creates a smoothly varying scalersmoothed object for use in the
 Audio Weaver.  Arguments:
    NAME - name of the module.
    INITIALSTATE - optional argument which specifies the default state
      of the trigger variable.  By default, INITIALSTATE = 0 meaning that
      the module comes up unmuted.