MixerSmoothedFract32

Overview

M-input x N-output smoothly varying mixer

Discussion

This module implements a fixed point version of full M-input x N-output mixer with a total of MxN coefficients. The coefficients are contained in the coeffs matrix with the gain from the ith input to the jth output is found at coeffs(i, j). This mixer implements smoothing on a sample-by-sample basis. Standard 1st order exponential smoothing is used. Gain adjustments are made to the coeffs matrix. Internally, the module holds a second matrix of instantaneous gains, currentCoeff, which smoothly approaches coeffs. The rate of the smoothing operation is controlled by smoothingTime.

When the module is bypassed, it copies the ith input channel to the ith output channel. If the module has more output channels than input channels, the remaining output channels are set to 0.

Type Definition

CODE

typedef struct _ModuleMixerSmoothedFract32
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 smoothingTime;                        // Time constant of the smoothing process
    fract32 smoothingCoeff;                       // Smoothing coefficient
    INT32 postShift;                              // Number of bits to shift
    FLOAT32* gain;                                // Linear gain
    fract32* targetGain;                          // Linear gain
    fract32* currentGain;                         // Linear gain
} ModuleMixerSmoothedFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
smoothingTime	float	parameter	0	10	0:500	msec
smoothingCoeff	fract32	derived	1	0.002081	Unrestricted
postShift	int	derived	1	6	Unrestricted
gain	float*	parameter	0	[1 x 2]	-60:20
targetGain	fract32*	derived	1	[1 x 2]	Unrestricted
currentGain	fract32*	state	1	[1 x 2]	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: mixer_smoothed_fract32_module.m

CODE

 M=mixer_smoothed_fract32_module(NAME, NUMOUT)
 Creates a smoothly varying multichannel mixer module for use in 
 the PC Audio Weaver environment.  The mixer has one input and 
 one output pin.  Each of the pins can contain multiple interleaved 
 channels.  The number of input channels is determined by the upstream
 audio module.  You must specify the number of output channels.  
 Arguments:
   NAME - name of the module.
   NUMOUT - number of output channels.