The Alternative Csound Reference Manual
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# vdelay

vdelay -- An interpolating variable time delay.

## Description

This is an interpolating variable time delay, it is not very different from the existing implementation (deltapi), it is only easier to use.

## Syntax

ar vdelay asig, adel, imaxdel [, iskip]

## Initialization

imaxdel -- Maximum value of delay in milliseconds. If adel gains a value greater than imaxdel it is folded around imaxdel. This should not happen.

iskip -- Skip initialization if present and nonzero

## Performance

With this unit generator it is possible to do Doppler effects or chorusing and flanging.

asig -- Input signal.

adel -- Current value of delay in milliseconds. Note that linear functions have no pitch change effects. Fast changing values of adel will cause discontinuities in the waveform resulting noise.

## Examples

      f1 0 8192 10 1
      ims     =          100             ; Maximum delay time in msec
      a1      oscil      10000, 1737, 1  ; Make a signal
      a2      oscil      ims/2, 1/p3, 1  ; Make an LFO
      a2      =          a2 + ims/2      ; Offset the LFO so that it is positive
      a3      vdelay     a1, a2, ims     ; Use the LFO to control delay time
              out        a3

Two important points here. First, the delay time must be always positive. And second, even though the delay time can be controlled in k-rate, it is not advised to do so, since sudden time changes will create clicks.

## See Also

vdelay3

## Credits

Author: Paris Smaragdis
MIT, Cambridge
1995

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