Overview

2-input x 1-output smoothly varying mixer module

Discussion

Mixes 2 inputs into a single output. The mixing gain parameters are exponentially smoothed (first order IIR) at the sample rate, with the smoothingTime parameter determining the smoothing rate for both of the gain values. The module's .gain1 and .gain2 variables specify the target gains for the mixing process. The module's .currentGain1 and .currentGain2 variables specify the instantaneous gains applied, and these exponentially approach the target gains. At build time, .currentGain1 is set to .gain1 and .currentGain2 is set to .gain2. This causes the mixers to startup in a converged state.

Type Definition

typedef struct _ModuleSMixer2x1Fract32
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 gain1;                                // Desired gain applied to first input channel
    FLOAT32 gain2;                                // Desired gain applied to second input channel
    FLOAT32 smoothingTime;                        // Time constant of the smoothing process
    fract32 targetGain1;                          // Fractional portion of the desired (or target) gain of the first channel
    fract32 currentGain1;                         // Fractional portion of the instantaneous gain of the first channel
    fract32 targetGain2;                          // Fractional portion of the desired (or target) gain of the second channel
    fract32 currentGain2;                         // Fractional portion of the instantaneous gain of the second channel
    fract32 smoothingCoeff;                       // Smoothing coefficient
    INT32 postShift;                              // Number of bits to shift after the fractional multiply. This is based on gain.range.
    FLOAT32 twoPowMinusPostShift;                 // 2^(-postShift). Used by to streamline the operation of the set function
} ModuleSMixer2x1Fract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
gain1	float	parameter	0	1	-10:10
gain2	float	parameter	0	1	-10:10
smoothingTime	float	parameter	0	10	0:1000	msec
targetGain1	fract32	derived	1	0.0625	Unrestricted
currentGain1	fract32	state	1	0.0625	Unrestricted
targetGain2	fract32	derived	1	0.0625	Unrestricted
currentGain2	fract32	state	1	0.0625	Unrestricted
smoothingCoeff	fract32	derived	1	0.002081	Unrestricted
postShift	int	derived	1	4	Unrestricted
twoPowMinusPostShift	float	derived	1	0.0625	Unrestricted

Pins

Input Pins

Name: in1

Description: audio input

Data type: fract32

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Name: in2

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: smixer2x1_fract32_module.m

 M=smixer2x1_fract32_module(NAME)
 Creates a 2-input 1-output smoothly varying mixer for use in the
 Audio Weaver environment.  Arguments:
    NAME - name of the module.
 Copyright 2007.  DSP Concepts, Inc.  All Rights Reserved.
 Author:  Paul Beckmann
 AudioWeaverModule [This tag makes it appear under awe_help]
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 Create the high-level object with interface variables only.
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