tonalisa/lib/sndlib/noise.rb

# noise.rb -- CLM -> Snd/Ruby translation of noise.ins

# Translator/Author: Michael Scholz <mi-scholz@users.sourceforge.net>
# Created: Wed Mar 19 05:16:56 CET 2003
# Changed: Thu Oct 15 00:17:48 CEST 2009

# Comments beginning with ;; are taken from noise.ins!

# attack_point(dur, attack, decay, total_x = 100.0)
# fm_noise(...)

# ;;; The "noise" instrument (useful for Oceanic Music):

require "ws"
require "env"
include Env

def attack_point(dur, attack, decay, total_x = 100.0)
  x = if 0.0 == attack
        if 0.0 == decay
          dur / 4.0
        else
          (dur - decay) / 4.0
        end
      else
        attack.to_f
      end
  total_x * (x / dur)
end

def fm_noise(start, dur, freq0,
             amp, ampfun, ampat, ampdc,
             freq1, glissfun, freqat, freqdc,
             rfreq0, rfreq1, rfreqfun, rfreqat, rfreqdc,
             dev0, dev1, devfun, devat, devdc,
             *args)
  degree, distance, reverb = nil
  optkey(args, binding,
         [:degree, kernel_rand(90.0)],
         [:distance, 1.0],
         [:reverb, 0.005])

  # ;; ampat = amp envelope attack time, and so on -- this instrument
  # ;; assumes your envelopes go from 0 to 100 on the x-axis, and that
  # ;; the "attack" portion ends at 25, the "decay" portion starts at
  # ;; 75.  "rfreq" is the frequency of the random number generator --
  # ;; if below about 25 hz you get automatic composition, above that
  # ;; you start to get noise.  well, you get a different kind of
  # ;; noise.  "dev" is the bandwidth of the noise -- very narrow
  # ;; gives a whistle, very broad more of a whoosh.  this is
  # ;; basically "simple fm", but the modulating signal is white
  # ;; noise.
  
  car = make_oscil(:frequency, freq0)
  mod = make_rand(:frequency, rfreq0, :amplitude, 1.0)
  dev_0 = hz2radians(dev0)
  
  # ;; next fix-up troubles in attack and decay times (there are lots
  # ;; of ways to handle this -- the basic problem is that these
  # ;; durned instruments end up having way too many parameters.  rick
  # ;; taube's common music replacement for pla should help, but just
  # ;; for old time's sake, we'll do it the way the ancients did it.
  # ;; (we could also package up this stuff in our own function,
  # ;; somewhat like the allvln function in vln.clm, leaving the
  # ;; instrument code to apply envelopes and other data to some
  # ;; patch).
  
  amp_attack = attack_point(dur, ampat, ampdc)
  amp_decay = 100.0 - attack_point(dur, ampdc, ampat)
  freq_attack = attack_point(dur, freqat, freqdc)
  freq_decay = 100.0 - attack_point(dur, freqdc, freqat)
  dev_attack = attack_point(dur, devat, devdc)
  dev_decay = 100.0 - attack_point(dur, devdc, devat)
  rfreq_attack = attack_point(dur, rfreqat, rfreqdc)
  rfreq_decay = 100.0 - attack_point(dur, rfreqdc, rfreqat)
  
  # ;; now make the actual envelopes -- these all assume we are
  # ;; thinking in terms of the "value when the envelope is 1"
  # ;; (i.e. dev1 and friends), and the "value when the envelope is 0"
  # ;; (i.e. dev0 and friends) -- over the years this seemed to make
  # ;; beginners happier than various other ways of describing the
  # ;; y-axis behaviour of the envelope.  all this boiler-plate for
  # ;; envelopes might seem overly elaborate when our basic instrument
  # ;; is really simple, but in most cases, and this one in
  # ;; particular, nearly all the musical interest comes from the
  # ;; envelopes, not the somewhat dull spectrum generated by the
  # ;; basic patch.
  
  dev_f = make_env(stretch_envelope(devfun, 25, dev_attack, 75, dev_decay),
                   hz2radians(dev1 - dev0), dur)
  amp_f = make_env(stretch_envelope(ampfun, 25, amp_attack, 75, amp_decay), amp, dur)
  freq_f = make_env(stretch_envelope(glissfun, 25, freq_attack, 75, freq_decay),
                    hz2radians(freq1 - freq0), dur)
  rfreq_f = make_env(stretch_envelope(rfreqfun, 25, rfreq_attack, 75, rfreq_decay),
                     hz2radians(rfreq1 - rfreq0), dur)

  run_instrument(start, dur, :degree, degree, :distance, distance, :reverb_amount, reverb) do
    env(amp_f) * oscil(car, env(freq_f) + (dev_0 + env(dev_f)) * rand(mod, env(rfreq_f)))
  end
end

=begin
with_sound(:statistics, true, :play, 1) do
  fm_noise(0, 1.8, 500,
           0.25, [0, 0, 25, 1, 75, 1, 100, 0], 0.1, 0.1,
           1000, [0, 0, 100, 1], 0.1, 0.1,
           10, 1000, [0, 0, 100, 1], 0, 0,
           100, 500, [0, 0, 100, 1], 0, 0)
  fm_noise(2, 1.8, 200,
           0.25, [0, 0, 25, 1, 75, 1, 100, 0], 0.1, 0.1,
           1000, [0, 0, 100, 1], 0.1, 0.1,
           10, 1000, [0, 0, 100, 1], 0, 0,
           100, 500, [0, 0, 100, 1], 0, 0)
end
=end

# noise.rb ends here