Overview

Module with different time delay for each channel specified in samples

Discussion

This time delay module has multiple input and multiple output channels. The delay in samples of each output channel can be independently set by the currentDelay array. The initial number of channels is specified at construction time and this also equals the length of the currentDelay array. Actual size of the currentDelay is updated in the prebuild function. Delays are specified in samples 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 delay in samples per channel is specified by the currentDelay array. Delays can be adjusted at run-time. The module applies smooth cross fading when adjusting the currentDelay at run-time.

Type Definition

typedef struct _ModuleDelayNChanSmoothed
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 smoothingTime;                        // Time constant of the cross fading process
    FLOAT32 oldGain;                              // Gain parameter for cross fading.
    FLOAT32 newGain;                              // Gain parameter for cross fading.
    INT32 fadingDone;                             // State variable to implement cross fading.
    INT32 maxDelay;                               // Maximum delay, in samples.
    INT32 stateHeap;                              // Heap in which to allocate memory.
    FLOAT32 smoothingCoeff;                       // Smoothing coefficient for cross fading.
    INT32* currentDelay;                          // Current delay per channel, in samples.
    INT32* stateIndex;                            // Index of the oldest state variable in the array of state variables.
    FLOAT32* state;                               // State variable array.
    INT32* prevDelay;                             // State array to implement cross fading.
} ModuleDelayNChanSmoothedClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
smoothingTime	float	parameter	0	10	0:1000	msec
oldGain	float	derived	0	1	Unrestricted
newGain	float	derived	0	0	Unrestricted
fadingDone	int	derived	0	0	0:1
maxDelay	int	const	1	100	Unrestricted	samples
stateHeap	int	const	1	561	Unrestricted
smoothingCoeff	float	derived	1	0.002081	Unrestricted
currentDelay	int*	parameter	0	[1 x 1]	0:100	samples
stateIndex	int*	state	1	[1 x 1]	Unrestricted
state	float*	state	1	[1 x 134]	Unrestricted
prevDelay	int*	state	1	[1 x 1]	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

Output Pins

Name: out

Description: audio output

Data type: float

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: delaynchan_smoothed_module.m

 M=delaynchan_smoothed_module(NAME, NUMCHANNELS, MAXDELAY, MEMHEAP)
 Creates a multi-channel time delay. 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 
 per channel. The module applies smooth transition between delay time 
 changes.
 
 Arguments:
    NAME - name of the module.
    NUMCHANNELS - number of channels for the module.
    MAXDELAY - maximum delay, in samples.
    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.