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. However, the module is not smoothly updating and you may get audible clicks when adjusting the currentDelay at run-time.

Type Definition

typedef struct _ModuleDelayNChan
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 maxDelay;                               // Maximum delay, in samples.
    INT32 stateHeap;                              // Heap in which to allocate memory.
    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.
} ModuleDelayNChanClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
maxDelay	int	const	1	100	Unrestricted	samples
stateHeap	int	const	1	561	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 103]	Unrestricted

Pins

Input Pins

Name: in

Description: audio input

Data type: {float, int, fract32}

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: audio output

Data type: {float, int, fract32}

MATLAB Usage

File Name: delaynchan_module.m

 M=delaynchan_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.
 
 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.