The Alternative Csound Reference Manual
Previous |  | Next

# zkmod

zkmod -- Facilitates the modulation of one signal by another.

## Description

Facilitates the modulation of one signal by another.

## Syntax

kr zkmod ksig, kzkmod

## Performance

ksig -- the input signal

kzkmod -- controls which zk 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 ksig. kzkmod can be i-rate or k-rate

zkmod facilitates the modulation of one signal by another, where the modulating signal comes from a zk variable. Either additive or mulitiplicative modulation can be specified.

## Examples

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

Example 1. Example of the zkmod opcode.

    /* zkmod.orc */
    ; Initialize the global variables.
    sr = 44100
    kr = 4410
    ksmps = 10
    nchnls = 2

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

    ; Instrument #1 -- a signal with jitter.
    instr 1
      ; Generate a k-rate signal goes from 30 to 2,000.
      kline line 30, p3, 2000

      ; Add the signal into zk variable #1.
      zkw kline, 1
    endin

    ; Instrument #2 -- generates audio output.
    instr 2
      ; Create a k-rate signal modulated the jitter opcode.
      kamp init 20
      kcpsmin init 40
      kcpsmax init 60
      kjtr jitter kamp, kcpsmin, kcpsmax

      ; Get the frequency values from zk variable #1.
      kfreq zkr 1
      ; Add the the frequency values in zk variable #1 to
      ; the jitter signal.
      kjfreq zkmod kjtr, 1

      ; Use a simple sine waveform for the left speaker.
      aleft oscil 20000, kfreq, 1
      ; Use a sine waveform with jitter for the right speaker.
      aright oscil 20000, kjfreq, 1

      ; Generate the audio output.
      outs aleft, aright

      ; Clear the zk variables, prepare them for
      ; another pass.
      zkcl 0, 2
    endin
    /* zkmod.orc */

    /* zkmod.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
    /* zkmod.sco */

## See Also

zamod, zkcl, zkr, zkwm, zkw

## Credits

Author: Robin Whittle
Australia
May 1997

Example written by Kevin Conder.

Previous | Home | Next
zkcl | Up | zkr