Delay

Overview

Time delay in which the delay is specified in samples

Discussion

A delay module, where the delay is specified as an integer number of samples. The delay is implemented such that delays as short as 0 samples can be realized. The module has one multichannel input and one multichannel output. The module can operate on multiple channels and applies the same delay to each channel.

At construction time, 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*numChannels. In addition, the instantaneous delay is specified through the interface variable, currentDelay. currentDelay is in the range of [0 maxDelay] and can be changed at run-time. Note that the module is not smoothly updating and you may get audible clicks when adjusting the currentDelay at run-time.

Type Definition

CODE

typedef struct _ModuleDelay
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 maxDelay;                               // Maximum delay, in samples. The size of the delay buffer is maxDelay*numChannels.
    INT32 currentDelay;                           // Current delay.
    INT32 stateIndex;                             // Index of the oldest state variable in the array of state variables.
    INT32 stateHeap;                              // Heap in which to allocate memory.
    FLOAT32* state;                               // State variable array.
} ModuleDelayClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
maxDelay	int	const	0	100	Unrestricted	samples
currentDelay	int	parameter	0	0	0:1:100	samples
stateIndex	int	state	1	0	Unrestricted
stateHeap	int	const	1	2	Unrestricted
state	float*	state	1	[1 x 101]	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: delay_module.m

CODE

 M=delay_module(NAME, MAXDELAY, MEMHEAP)
 Creates an integer time delay for use in the Audio Weaver environment.  
 
 Arguments:
    NAME - name of 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 (the default).
            'AWE_HEAP_FAST2SLOW' - use internal memory. If this fails
               then use external memory (the default).