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(8.D.2.6) DelayInterp

Overview

Modulated time delay using linear or cubic interpolation

Discussion

This module implements a time-varying delay. The first input pin (mod) specifies the modulation factor; the second input pin is the multichannel audio signal. The module computes the instantaneous delay to apply on a sample-by-sample basis. The instantaneous delay is a floating-point value computed as:

delay[n] = M.currentDelay + mod[n] * M.modDepth

The modulation factor input is usually in the range [-1 +1], but this is not checked by the module.

The instantaneous delay time is a floating-point value and the module implements fractional sample interpolation using linear or cubic (third order) interpolation.

Type Definition

typedef struct _ModuleDelayInterp { ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure INT32 maxDelay; // Maximum delay that can be realized, in samples. The size of the delay buffer (maxDelay+1)*numChannels INT32 interpType; // Interpolation type. 0 - Linear, 1 - Cubic FLOAT32 currentDelay; // Current delay FLOAT32 modDepth; // Maximum depth, in samples, of the modulation signal 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 } ModuleDelayInterpClass;

Variables

Properties

Name

Type

Usage

isHidden

Default value

Range

Units

maxDelay

int

const

0

100

1:100000

samples

interpType

int

const

0

0

0:1

 

currentDelay

float

parameter

0

0

0:100

samples

modDepth

float

parameter

0

0

0:100

samples

stateIndex

int

state

1

0

Unrestricted

 

stateHeap

int

const

1

561

Unrestricted

 

state

float*

state

1

[1 x 101]

Unrestricted

 

Pins

Input Pins

Name: mod

Description: modulation input

Data type: float

Channel range: 1

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

 

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

MATLAB Usage

File Name: delay_interp_module.m

M=delay_interp_module(NAME, MAXDELAY, MEMHEAP, INTERP_TYPE) Creates a fractional sample time delay for use in the Audio Weaver. Arguments: 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. '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. INTERP_TYPE - Interpolation type. Linear or Cubic.

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