Class: SynthBlocks::Fx::Chorus

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

Overview

A simple chorus

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(sample_rate, phase: 0.0, rate: 0.5, delay_time: 7.0, mix: 0.5) ⇒ Chorus

Create new Chorus instance

phase allows you to shift the phase of the delayed signal additionally

rate is the LFO rate in Hz

delay_time is the maximum delay time in ms

mix is the ratio between original and delayed signal. 1.0 would mean only delayed signal (which wouldn’t make any sense)



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# File 'lib/synth_blocks/fx/chorus.rb', line 21

def initialize(sample_rate, phase: 0.0, rate: 0.5, delay_time: 7.0, mix: 0.5)
  @sample_rate = sample_rate
  @rate = rate
  @delay_time = delay_time
  @mix = mix

  @z1 = 0.0
  @sign = 0
  @lfo_phase = phase * 2.0 - 1.0
  @lfo_step_size = (4.0 * @rate / @sample_rate)
  @lfo_sign = 1.0

  # Compute required buffer size for desired delay and allocate it
  # Add extra point to aid in interpolation later
  @delay_line_length = ((@delay_time * @sample_rate * 0.001).floor * 2).to_i
  @delay_line = [0.0] * @delay_line_length
  @write_ptr = @delay_line_length - 1
  @lp = SynthBlocks::Core::OnePoleLP.new
  @output = 0.0
end

Instance Attribute Details

#delay_time=(value) ⇒ Object (writeonly)

:nodoc:



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# File 'lib/synth_blocks/fx/chorus.rb', line 9

def delay_time=(value)
  @delay_time = value
end

#mix=(value) ⇒ Object (writeonly)

:nodoc:



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# File 'lib/synth_blocks/fx/chorus.rb', line 9

def mix=(value)
  @mix = value
end

#phase=(value) ⇒ Object (writeonly)

:nodoc:



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# File 'lib/synth_blocks/fx/chorus.rb', line 9

def phase=(value)
  @phase = value
end

#rate=(value) ⇒ Object (writeonly)

:nodoc:



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# File 'lib/synth_blocks/fx/chorus.rb', line 9

def rate=(value)
  @rate = value
end

Instance Method Details

#run(input) ⇒ Object

run the chorus



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# File 'lib/synth_blocks/fx/chorus.rb', line 44

def run(input)
  # Get delay time
  offset = (next_lfo() * 0.3 + 0.4) * @delay_time * @sample_rate * 0.001

  # Compute the largest read pointer based on the offset.  If ptr
  # is before the first delayline location, wrap around end point
  ptr = @write_ptr - offset.floor;
  ptr += @delay_line_length - 1 if ptr < 0


  ptr2 = ptr - 1
  ptr2 += @delay_line_length - 1 if ptr2 < 0

  frac = offset - offset.floor.to_f
  @output = @delay_line[ptr2] + @delay_line[ptr] * (1.0 - frac) - (1.0 - frac) * @z1
  @z1 = @output

  # Low pass
  @lp.run(@output, 0.95)

  # Write the input sample and any feedback to delayline
  @delay_line[@write_ptr] = input

  # Increment buffer index and wrap if necesary
  @write_ptr += 1
  @write_ptr = 0 if @write_ptr >= @delay_line_length
  return (@output * @mix) + (input * (1.0-@mix))
end