Overview

A smoothed mixer module with M outputs and N inputs

Discussion

This time delay module has multiple input and multiple output channels. Smoothed delay can be applied at each intersections of the input and output lines. The delays and gains to be applied at each intersection comes from the control pin. Delays are specified in milliseconds and are in the range of [0 MAXDELAY].

At construction time, you specify the maximum delay (maxDelay) of the module. The variable, maxDelay determines the size of the internal state buffer. The size of the internal state buffer equals (maxDelay+1)*numChannels samples. The module applies smooth cross fading when delay or gain values are changed at run-time.

Type Definition

typedef struct _ModuleMultichannelMixerSmoothed
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 maxDelayTime;                         // Maximum delay, in milliseconds.
    FLOAT32 smoothingTimeDelay;                   // Time constant of the cross fading process of delay
    FLOAT32 smoothingTimeGain;                    // Time constant of the cross fading process of gain
    FLOAT32 smoothingCoeff;                       // Smoothing coefficient for cross fading of delays.
    FLOAT32 smoothingCoeffGain;                   // Smoothing coefficient for cross fading of gains.
    INT32 stateHeap;                              // Heap in which to allocate memory.
    INT32 maxDelay;                               // Max delay in samples.
    INT32* prevDelay;                             // Array holding previous delay values.
    INT32* currentDelay;                          // Array holding current delay values.
    FLOAT32* prevGain;                            // Array holding previous gain values.
    FLOAT32* currentGain;                         // Array holding current gain values.
    FLOAT32* oldGain;                             // Gain parameter for cross fading of delay.
    FLOAT32* newGain;                             // Gain parameter for cross fading of delay.
    INT32* fadingDone;                            // State variable to implement cross fading of delay.
    INT32* stateIndex;                            // Index of the oldest state variable in the array of state variables.
    FLOAT32* state;                               // State variable array.
} ModuleMultichannelMixerSmoothedClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
maxDelayTime	float	const	0	10	0:10	msec
smoothingTimeDelay	float	parameter	0	10	0:1000	msec
smoothingTimeGain	float	parameter	0	10	0:1000	msec
smoothingCoeff	float	derived	1	0.002081	Unrestricted
smoothingCoeffGain	float	derived	1	0.002081	Unrestricted
stateHeap	int	const	1	561	Unrestricted
maxDelay	int	const	1	480	Unrestricted
prevDelay	int*	state	1	[1 x 1]	Unrestricted	samples
currentDelay	int*	state	1	[1 x 1]	Unrestricted	samples
prevGain	float*	state	1	[1 x 1]	Unrestricted	samples
currentGain	float*	state	1	[1 x 1]	Unrestricted	samples
oldGain	float*	state	1	[1 x 1]	Unrestricted
newGain	float*	state	1	[1 x 1]	Unrestricted
fadingDone	int*	state	1	[1 x 1]	0:1
stateIndex	int*	state	1	[1 x 1]	Unrestricted
state	float*	state	1	[1 x 514]	Unrestricted

Pins

Input Pins

Name: in

Description: audio input

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Name: cntrl

Description: Control pin for MxN gain and delays

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: Audio output

Data type: float

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: multichannel_mixer_smoothed_module.m

 M=multichannel_mixer_smoothed_module(NAME, NUMCHANNELS, MAXDELAY, MEMHEAP)
 Creates a multi-channel time delay in which the delay times are specified
 in milliseconds. The module has a multichannel input pin
 and an multichannel output pin. Each output channel is a delayed
 version of the corresponding input channel with different delay times 
 for each channel. The module applies smooth transition between delay time 
 changes.
 
 Arguments:
    NAME - name of the module.
    NUMCHANNELS - number of output channels for the module.
    MAXDELAY - maximum delay, in milliseconds.
    MEMHEAP - specifies the memory heap to use to allocate the main
         state buffer. This is a string and follows the memory allocation
         enumeration in Framework.h. Allowable values are:
            'AWE_HEAP_FAST' - always use internal DM memory.
            'AWE_HEAP_FASTB' - always use internal PM memory.
            'AWE_HEAP_SLOW' - always use external memory.
            'AWE_HEAP_FAST2SLOW' - use internal memory. If this fails
               then use external memory (the default).
            'AWE_HEAP_FASTB2SLOW' - use internal memory. If this fails
               then use external memory.