Class: SynthBlocks::Fx::GVerb

Inherits:
Object
  • Object
show all
Defined in:
lib/synth_blocks/fx/g_verb.rb,
lib/synth_blocks/fx/g_verb.rb

Overview

GVerb is a relatively simple reverb implementation

Constant Summary collapse

FDNORDER =

:nodoc:

4

Instance Method Summary collapse

Constructor Details

#initialize(srate, max_room_size: 120.0, room_size: 50.0, rev_time: 2.0, damping: 0.3, spread: 15.0, input_bandwidth: 1.5, early_level: 0.8, tail_level: 0.5, mix: 0.2) ⇒ GVerb

Create new GVerb instance

max_room_size is the maximum room size you’ll use

room_size is the current room size



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# File 'lib/synth_blocks/fx/g_verb.rb', line 90

def initialize(srate, max_room_size: 120.0, room_size: 50.0, rev_time: 2.0, damping: 0.3, spread: 15.0, input_bandwidth: 1.5, early_level: 0.8, tail_level: 0.5, mix: 0.2)
  @rate = srate
  @damping = damping
  @max_room_size = max_room_size
  @room_size = room_size
  @rev_time = rev_time
  @early_level = early_level
  @tail_level = tail_level
  @mix = mix
  @max_delay = @rate * @max_room_size / 340.0
  @largest_delay = @rate * @room_size / 340.0
  @input_bandwidth = input_bandwidth;
  @input_damper = Damper.new(1.0 - @input_bandwidth)


  @fdndels = FDNORDER.times.map do |i|
    FixedDelay.new(@max_delay + 1000)
  end
  @fdngains = Array.new(FDNORDER)
  @fdnlens = Array.new(FDNORDER)

  @fdndamps = FDNORDER.times.map do |i|
    Damper.new(@damping)
  end

  ga = 60.0;
  gt = @rev_time;
  ga = 10.0 ** (-ga / 20.0)
  n = @rate * gt
  @alpha = ga ** (1.0 / n)
  gb = 0.0;
  FDNORDER.times do |i|
    gb = 1.000000*@largest_delay if (i == 0)
    gb = 0.816490*@largest_delay if (i == 1)
    gb = 0.707100*@largest_delay if (i == 2)
    gb = 0.632450*@largest_delay if (i == 3)

    @fdnlens[i] = nearest_prime(gb, 0.5);
    @fdnlens[i] = gb.round;
    @fdngains[i] = -(@alpha ** @fdnlens[i])
  end

  @d = Array.new(FDNORDER)
  @u = Array.new(FDNORDER)
  @f = Array.new(FDNORDER)

  # DIFFUSER SECTION

  diffscale = @fdnlens[3].to_f/(210+159+562+410);
  spread1 = spread.to_f
  spread2 = 3.0*spread

  b = 210
  r = 0.125541
  a = spread1*r
  c = 210+159+a
  cc = c-b
  r = 0.854046
  a = spread2*r
  d = 210+159+562+a
  dd = d-c
  e = 1341-d

  @ldifs = [
    Diffuser.new((diffscale*b),0.75),
    Diffuser.new((diffscale*cc),0.75),
    Diffuser.new((diffscale*dd),0.625),
    Diffuser.new((diffscale*e),0.625)
  ]

  b = 210
  r = -0.568366
  a = spread1*r
  c = 210+159+a
  cc = c-b
  r = -0.126815;
  a = spread2*r
  d = 210+159+562+a
  dd = d-c
  e = 1341-d

  @rdifs = [
    Diffuser.new((diffscale*b),0.75),
    Diffuser.new((diffscale*cc),0.75),
    Diffuser.new((diffscale*dd),0.625),
    Diffuser.new((diffscale*e),0.625)
  ]


  # Tapped delay section */

  @tapdelay = FixedDelay.new(44000)
  @taps = Array.new(FDNORDER)
  @tapgains = Array.new(FDNORDER)

  @taps[0] = 5+0.410*@largest_delay
  @taps[1] = 5+0.300*@largest_delay
  @taps[2] = 5+0.155*@largest_delay
  @taps[3] = 5+0.000*@largest_delay

  FDNORDER.times do |i|
    @tapgains[i] = @alpha ** @taps[i]
  end
end

Instance Method Details

#run(x) ⇒ Object

runs a value through the reverb, returns the reverberated signal mixed with the original.



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# File 'lib/synth_blocks/fx/g_verb.rb', line 199

def run(x)
  if x.nan? || x.abs > 100000.0
    x = 0.0
  end

  z = @input_damper.run(x)
  z = @ldifs[0].run(z)
  FDNORDER.times do |i|
    @u[i] = @tapgains[i] * @tapdelay.read(@taps[i])
  end

  @tapdelay.write(z)

  FDNORDER.times do |i|
    @d[i] = @fdndamps[i].run(@fdngains[i] * @fdndels[i].read(@fdnlens[i]))
  end

  sum = 0.0
  sign = 1.0
  FDNORDER.times do |i|
    sum += sign * (@tail_level * @d[i] + @early_level * @u[i])
    sign = -sign
  end

  sum += x* @early_level

  lsum = sum
  # rsum = sum

  @f = fdn_matrix(@d)

  FDNORDER.times do |i|
    @fdndels[i].write(@u[i] + @f[i])
  end

  lsum = @ldifs[1].run(lsum)
  lsum = @ldifs[2].run(lsum)
  lsum = @ldifs[3].run(lsum)

  # rsum = @rdifs[1].run(rsum)
  # rsum = @rdifs[2].run(rsum)
  # rsum = @rdifs[3].run(rsum)

  lsum = x * (1.0 - @mix) + lsum * @mix
  # rsum = x * (1.0 - mix) + rsum * mix
  return lsum
end