#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.


@racketblock[
(with-sc3
 (lambda (fd)
   (async fd (b-alloc 0 44100 1))))
]


@racketblock[
(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))))
]