zamod

zamod — Modulates one a-rate signal by a second one.

Description

Modulates one a-rate signal by a second one.

Syntax

ares zamod asig, kzamod

Performance

asig -- the input signal

kzamod -- controls which za variable is used for modulation. A positive value means additive modulation, a negative value means multiplicative modulation. A value of 0 means no change to asig.

zamod modulates one a-rate signal by a second one, which comes from a za variable. The location of the modulating variable is controlled by the i-rate or k-rate variable kzamod. This is the a-rate version of zkmod.

Examples

Here is an example of the zamod opcode. It uses the files zamod.orc and zamod.sco.

Example 444. Example of the zamod opcode.

/* zamod.orc */
; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1

; Initialize the ZAK space.
; Create 2 a-rate variables and 2 k-rate variables.
zakinit 2, 2

; Instrument #1 -- a simple waveform.
instr 1
  ; Vary an a-rate signal linearly from 20,000 to 0.
  asig line 20000, p3, 0

  ; Send the signal to za variable #1.
  zaw asig, 1
endin

; Instrument #2 -- generates audio output.
instr 2
  ; Generate a simple sine wave.
  asin oscil 1, 440, 1
  
  ; Modify the sine wave, multiply its amplitude by 
  ; za variable #1.
  a1 zamod asin, -1

  ; Generate the audio output.
  out a1

  ; Clear the za variables, prepare them for 
  ; another pass.
  zacl 0, 2
endin
/* zamod.orc */

        
/* zamod.sco */
; Table #1, a sine wave.
f 1 0 16384 10 1

; Play Instrument #1 for 2 seconds.
i 1 0 2
; Play Instrument #2 for 2 seconds.
i 2 0 2
e
/* zamod.sco */

        

See Also

zacl, ziw, ziwm

Credits

Author: Robin Whittle
Australia
May 1997

Example written by Kevin Conder.