Overview

Fixed-point smoothed mute with synchronous requests

Discussion

Smoothly change the gain of all input channels to 0 (mute) or 1 (unmute). You have full control over the time that it takes to mute and unmute. Gain values applied are available on an optional second output pin.

Set the .asyncCommand or .syncCommand variable to 1 (UNMUTE) to change gain smoothly to 0 after unmuteTime ms. Set to 2 (MUTE) to change gain to 1 after muteTime ms. When asyncCommand is set, the set function returns immediately. When changing syncCommand, the set function returns only after the target has been reached.

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

Type Definition

typedef struct _ModuleMuteSyncFract32
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 isMuted;                                // Boolean for target gain: 1 means silence
    INT32 asyncCommand;                           // Start changing the gain without waiting for completion: 1=unmute, 2=mute
    INT32 syncCommand;                            // Change the gain and return only when finished: 1=unmute, 2=mute
    FLOAT32 muteTime;                             // Muting time in msec
    FLOAT32 unmuteTime;                           // Unmuting time in msec
    INT32 compatSync;                             // When true, isMuted compatibility is synchronous
    INT32 muteState;                              // Current muting action: 0=not set, 1=unmuted, 2=muted, 3=unmute changing, 4=mute changing
    fract32 currentGain;                          // Gain being applied to start of next sample block
    fract32 muteRotateI;                          // Imaginary part of multiplier to rotate phasor while muting
    INT32 syncState;                              // Active synchronous target state
    INT32 muteSamples;                            // Muting time in samples
    INT32 unmuteSamples;                          // Unmuting time in samples
    fract32 muteRotateR;                          // Real part of multiplier to rotate phasor while muting
    fract32 unmuteRotateR;                        // Real part of multiplier to rotate phasor while unmuting
    fract32 unmuteRotateI;                        // Imaginary part of multiplier to rotate phasor while unmuting
    fract32 phasorR;                              // Real part of complex phasor used to compute cosine
    fract32 phasorI;                              // Imaginary part of complex phasor used to compute cosine
    INT32 sampleTime;                             // Counts samples since the start of the active mute or unmute operation
} ModuleMuteSyncFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
isMuted	int	state	0	0	0:1
asyncCommand	int	state	0	0	0:2
syncCommand	int	state	0	0	0:2
muteTime	float	parameter	0	5	1:1000
unmuteTime	float	parameter	0	50	1:1000
compatSync	int	state	0	1	Unrestricted
muteState	int	state	0	1	0:4
currentGain	fract32	derived	0	0	Unrestricted
muteRotateI	fract32	derived	0	0.01309	Unrestricted
syncState	int	derived	1	1	Unrestricted
muteSamples	int	derived	1	240	Unrestricted
unmuteSamples	int	derived	1	2400	Unrestricted
muteRotateR	fract32	derived	1	0.9999	Unrestricted
unmuteRotateR	fract32	derived	1	1	Unrestricted
unmuteRotateI	fract32	derived	1	0.001309	Unrestricted
phasorR	fract32	state	1	0	Unrestricted
phasorI	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

MATLAB Usage

File Name: mute_sync_fract32_module.m

 M = mute_sync_fract32_module(NAME, DEFSYNC, GAINPIN)
 Create an extended fixed-point smoothed mute module that supports a
 group of synchronous variables for which the set returns only when the
 resquested mute or unmute operation has completed. Muting and muting
 smoothing is performed using raised cosine windows as in MuteUnmute so
 that the gain reaches 0 or 1 after the specified time constant.
 Arguments:
       NAME        The name of the module
       DEFSYNC     Turns synchronous muting on/off (default = 1 = ON)
       GAINPIN     Indicator for adding a gain output pin 
                   (default = 0 = OFF)
 Copyright 2010-2016 DSP Concepts, Inc. All rights reserved.