CAST Transforms: Vibrato

Introduction

Periodic frequency modulation. The classic LFO connected to frequency.

Parameters

Message	Argument(s)	Type(s)	Description
speed	Vibrato speed in Hertz	Float	Sets the speed of the LFO that scales the frequency of each partial.
depth	Vibrato depth	Float	Sets vibrato depth (see below for the units of this parameter).

The frequency of each partial is multiplied by

1 + (depth * sin(2*pi*speed*time))

Depth defines the percent frequency deviation, in linear space:

• A depth of 0 means no vibrato
• A depth of .5 means vary between an octave down (0.5 times the original frequency) and a fifth up (1.5 times the original frequency)
• A depth of 1 means vary between 0 Hertz (0 times the original frequency) and an octave up (2 times the original frequency).

Reasonable depth values are around 0.02.

Note that the timbral effects of this frequency scaling are the same as those from the transpose transform.

Examples

For the following examples execute: demosoftcast /usr/local/cast/lib/data/coleman/lick1.fmt.

No vibrato :

/voices/0/vibrato/speed 5.0
/voices/0/vibrato/depth 0.0
/voices/0/tm/goto 0.0

Small amount:

/voices/0/vibrato/speed 5.0
/voices/0/vibrato/depth 0.03
/voices/0/tm/goto 0.0

Large:

/voices/0/vibrato/speed 5.0
/voices/0/vibrato/depth 0.07
/voices/0/tm/goto 0.0

Slow:

/voices/0/vibrato/speed 1.0
/voices/0/vibrato/depth 0.04
/voices/0/tm/goto 0.0

Fast:

/voices/0/vibrato/speed 15.0
/voices/0/vibrato/depth 0.04
/voices/0/tm/goto 0.0