vdelay, vdelay3

  ar      vdelay     asig, adel, imaxdel[, iskip]
  ar      vdelay3    asig, adel, imaxdel[, iskip]

Description

This is an interpolating variable time delay, it is not very different from the existing implementation (deltapi), it is only easier to use. vdelay3 is experimental, and is the same as vdelay, except that it uses cubic interpolation. (New in Vesrion 3.50.)

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.

Example

  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.

Author

Paris Smaragdis
MIT, Cambridge
1995