#lang scribble/manual
@(require (for-label racket))

@title{(buf-allpass-c buf in delaytime decaytime)}

Buffer based all pass delay line with cubic interpolation

All pass delay line with cubic interpolation which uses a buffer
for its internal memory. See also Bufallpass-n which uses no
interpolation, and Bufallpass-l which uses linear
interpolation. Cubic interpolation is more computationally
expensive than linear, but more accurate.

See also allpass-c.

buf - buffer number.

in - the input signal.

delaytime - delay time in seconds.

decaytime - time for the echoes to decay by 60 decibels. If this
            time is negative then the feedback coefficient will be
            negative, thus emphasizing only odd harmonics at an
            octave lower.

(with-sc3
 (lambda (fd)
   (async fd (b-alloc 0 44100 1))))

(let ((x (mul3 (decay (dust ar 1) 0.2) (white-noise ar) 0.5)))
  (audition (out 0 (buf-allpass-n 0 x 0.25 6))))