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zamod

Modulates one a-rate signal by a second one.

Syntax

ares = zamod(asig, kzamod)

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 file zamod.csd.

Example of the zamod opcode.
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<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in    No messages
-odac           -iadc     -d     ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
; -o zamod.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

; 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


</CsInstruments>
<CsScore>

; 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


</CsScore>
</CsoundSynthesizer>

See also

Zak Patch System

Credits

Author: Robin Whittle
Australia
May 1997

New in version 3.45

Example written by Kevin Conder.