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

@title{(grain-fm nc tr dur carfreq modfreq index pan envbuf)}


Granular synthesis with frequency modulated sine tones

nc - the number of channels to output. If 1, mono is returned and
     pan is ignored.

tr - a kr or ar trigger to start a new grain. If ar, grains after
     the start of the synth are sample accurate.

The following args are polled at grain creation time

dur - size of the grain.

carfreq - the carrier freq of the grain generators internal
          oscillator

modfreq - the modulating freq of the grain generators internal
          oscillator

index - the index of modulation

pan - a value from -1 to 1. Determines where to pan the output in
      the same manner as pan-az.

envbuf - the buffer number containing a singal to use for the grain
         envelope. -1 uses a built-in Hanning envelope.


@racketblock[
(let* ((x (mouse-x kr -0.5 0.5 0 0.1))
       (y (mouse-y kr 0 400 0 0.1))
       (n (white-noise kr))
       (fd (add 440 (mul n y)))
       (t (impulse kr 10 0))
       (i (lin-lin (lf-noise1 kr 500) -1 1 1 10)))
  (audition (out 0 (mul (grain-fm 2 t 0.1 fd 200 i x -1) 0.1))))
]