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(8.D.1.2) GranularSynthesisDelay

Owned by Catherine Spain
Apr 10, 2023
7 min read

Overview

Synchronous Granular Synthesis Module Delay

Discussion

This module implements (synchronous) granular synthesis functionality. It uses a delay line to store samples from a real-time input stream. Each grain reads sound from the delay line with a potentially different delay time and playback rate. At instantiation time, you must specify the maximum delay time in milliseconds, max grain size in milliseconds. These values determine the sizes of each internal state buffers to hold audio samples and intermediate results.

The input pin fRatio is a floating-point number and specifies the step size between samples as they are played back. Internally, fRatio is smoothed on a block by block basis using the .smoothingTime variable.

If "playDir" parameter has been selected to "backward" or, if fRatio has a negative value [range 0..-1] and "playDir" parameter has been selected to "auto", the delayline buffer is played back in backward direction,

The module has input pin named delayPos that specifies the starting position of the grains at audio rate. Values in the input pin ranges between 0 and 1, and the actual offset in the file is determined be multiplying it with the delayline length. The starting offset of each grain is determined internally and the value at that offset is read from delayPos.

The module has input pin named panMod that specifies the panning coefficients of the grains at audio rate. Values in the input pin ranges between 0 and 1, the specified value is considered as panning coefficient for left channel. 1-coeff is considered as the panning for right channel.

Type Definition

typedef struct _ModuleGranularSynthesisDelay { ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure INT32 grainSize; // Sets the length of each grain, denoted in milliseconds INT32 grainDensity; // Sets the number of grain samples per second INT32 playDir; // Playback direction, 0=Forward, 1=Backward, 2=Auto (derived from fRatio input pin) FLOAT32 gain; // The peak level of the window INT32 smoothingTime; // Time constant of the pitch smoothing process INT32 maxDelayTime; // Maximum delay, in milliseconds. INT32 windowLength; // Number of coefficients for current window INT32 maxDelaySamples; // Maximum delay in samples. INT32 writeIndex; // Write offset in the delay buffer INT32 maxGrainSize; // Maximum grain size in ms INT32 maxDensity; // Max density in grains per sec FLOAT32 maxRate; // Highest allowed rate of playback that can be specified UINT32 pinID; // Specifies which control pins are available INT32 stateHeap; // Heap in which to allocate state buffer memory. INT32 maxOverlapGrains; // Number of max. overlapping grains per maxGrainSize INT32 grainSizeSamples; // Length of each grain in samples INT32 interonsetTime; // Time between temporally adjacent grain onsets FLOAT32 windowRatio; // Sample ratio of the window coefficients FLOAT32 smoothingCoeff; // Smoothing (pitch) coefficient INT32 grainIndex; // Current used vector index INT32 interonsetCnt; // Current interonset counter FLOAT32 smoothedFRatio; // Current (smoothed) rate at which audio is read from the input buffer FLOAT32* window; // Window coefficients FLOAT32* window_coeffs; // Window coefficients FLOAT32* delayBuffer; // State variable array. INT32* GrainDelayIndex; // Curr delayline index of the intermediate vector element FLOAT32* GrainDelayIndexF; // Curr delayline index fract of the intermediate vector element FLOAT32* GrainDelayFStep; // Curr delayline step size of the intermediate vector element INT32* GrainEnvIndex; // Curr envelope index of the intermediate vector element FLOAT32* GrainEnvIndexF; // Curr envelope index fract of the intermediate vector element FLOAT32* GrainEnvFStep; // Curr envelope step size of the intermediate vector element INT32* GrainOffset; // Curr grain offset of the intermediate vector element FLOAT32* GrainPanCoeff; // Curr panning coefficient of the intermediate vector element INT32* GrainStatus; // Curr status ("active"/"inactive") of the intermediate vector element } ModuleGranularSynthesisDelayClass;

Variables

Properties

Name

Type

Usage

isHidden

Default value

Range

Units

grainSize

int

parameter

0

100

1:100

msec

grainDensity

int

parameter

0

10

1:100

 

playDir

int

parameter

0

0

0:2

 

gain

float

parameter

0

1

0:1

 

smoothingTime

int

parameter

0

100

0:1000

msec

maxDelayTime

int

const

0

500

0:500

msec

windowLength

int

const

0

32

Unrestricted

 

maxDelaySamples

int

derived

0

24000

Unrestricted

samples

writeIndex

int

state

0

0

Unrestricted

 

maxGrainSize

int

const

1

100

0:100

msec

maxDensity

int

const

1

100

0:100

grains per sec

maxRate

float

const

1

5

Unrestricted

 

pinID

uint

const

1

1

Unrestricted

 

stateHeap

int

const

1

561

Unrestricted

 

maxOverlapGrains

int

const

1

10

Unrestricted

 

grainSizeSamples

int

derived

1

4800

Unrestricted

 

interonsetTime

int

derived

1

4800

Unrestricted

 

windowRatio

float

derived

1

1

Unrestricted

 

smoothingCoeff

float

derived

1

0.006644

Unrestricted

 

grainIndex

int

state

1

0

Unrestricted

 

interonsetCnt

int

state

1

0

Unrestricted

 

smoothedFRatio

float

state

1

1

Unrestricted

 

window

float*

parameter

1

[35 x 1]

Unrestricted

 

window_coeffs

float*

parameter

0

[32 x 1]

Unrestricted

 

delayBuffer

float*

state

1

[1 x 24003]

Unrestricted

 

GrainDelayIndex

int*

state

1

[1 x 10]

Unrestricted

 

GrainDelayIndexF

float*

state

1

[1 x 10]

Unrestricted

 

GrainDelayFStep

float*

state

1

[1 x 10]

Unrestricted

 

GrainEnvIndex

int*

state

1

[1 x 10]

Unrestricted

 

GrainEnvIndexF

float*

state

1

[1 x 10]

Unrestricted

 

GrainEnvFStep

float*

state

1

[1 x 10]

Unrestricted

 

GrainOffset

int*

state

1

[1 x 10]

Unrestricted

 

GrainPanCoeff

float*

state

1

[1 x 10]

Unrestricted

 

GrainStatus

int*

state

1

[1 x 10]

Unrestricted

 

Pins

Input Pins

Name: in

Description: Input audio

Data type: float

Channel range: 1

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

 

Name: fRatio

Description: Specifies playback ratio

Data type: float

Channel range: 1

Block size range: 1

Sample rate range: Unrestricted

Complex support: Real

 

Name: delayPos

Description: Start point of the grain, located relative within the delayline between 0..1(maxDelay)

Data type: float

Channel range: 1

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

 

Name: panMod

Description: Controls panning for each grain; relative distribution between 0(max left)..1(max right)

Data type: float

Channel range: 1

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: audio

Description: Output data

Data type: float

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

 

Channel count: 1

Block size: 32

Sample rate: 48000

 

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: granular_synthesis_delay_module.m