hsboscil

  ar      hsboscil  kamp, ktone, kbrite, ibasfreq, iwfn, ioctfn[, ioctcnt[, iphs]]

Description

An oscillator which takes tonality and brightness as arguments, relative to a base frequency.

Initialization

ibasfreq - base frequency to which tonality and brighness are relative

iwfn - function table of the waveform, usually a sine

ioctfn - function table used for weighting the octaves, usually something like:

  f1 0  1024  -19  1  0.5  270  0.5

ioctcnt - number of octaves used for brightness blending. Must be in the range 2 to 10. Default is 3.

iphs - initial phase of the oscillator. If iphs = -1, initialization is skipped.

Performance

kamp - amplitude of note

ktone - cyclic tonality parameter relative to ibasfreq in logarithmic octave, range 0 to 1, values > 1 can be used, and are internally reduced to frac(ktone).

kbrite - brightness parameter relative to ibasfreq, achieved by weighting ioctcnt octaves. It is scaled in such a way, that a value of 0 corresponds to the orignal value of ibasfreq, 1 corresponds to one octave above ibasfreq, -2 corresponds to two octaves below ibasfreq, etc. kbrite may be fractional.

hsboscil takes tonality and brightness as arguments, relative to a base frequency (ibasfreq). Tonality is a cyclic parameter in the logarithmic octave, brightness is realized by mixing multiple weighted octaves. It is useful when tone space is understood in a concept of polar coordinates.

Making ktone a line, and kbrite a constant, produces Risset's glissando.

Oscillator table iwfn is always read interpolated. Performance time requires about ioctcnt * oscili.

Examples

  giwave    ftgen      1, 0, 1024, 10, 1, 1, 1, 1         ; synth wave
  giblend   ftgen      2, 0, 1024, -19, 1, 0.5, 270, 0.5  ; blending window
  
 instr 1                                                   ; endless glissando
  ktona     line       0,10,1
  asig      hsboscil   10000, ktona, 0, 200, giwave, giblend, 5
            out        asig
 endin
  
 instr 2                                                   ; MIDI instrument: all octaves sound alike,
  itona     octmidi                                       ; velocity is mapped to brightness
  ibrite    ampmidi    3
  ibase     =          cpsoct(6)
  kenv      expon      20000, 1, 100
  asig      hsboscil   kenv, itona, ibrite, ibase, giwave, giblend, 5
            out        asig
 endin

Author

Peter Neubäcker
Munich, Germany
August, 1999
New in Csound version 3.58