Class: SynthBlocks::Fx::Compressor

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

Overview

simple compresor taken from www.musicdsp.org/en/latest/Effects/204-simple-compressor-class-c.html

Constant Summary collapse

DC_OFFSET =

:nodoc:

1.0E-25
LOG_2_DB =

:nodoc:

8.6858896380650365530225783783321
DB_2_LOG =

:nodoc:

0.11512925464970228420089957273422

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(srate, attack: 10.0, release: 100.0, ratio: 1.0, threshold: 0.0) ⇒ Compressor

Create compressor instance

attack is the attack time in ms

release is the release time in ms

ratio is the compresor ratio

threshold is the knee threshold



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# File 'lib/synth_blocks/fx/compressor.rb', line 68

def initialize(srate, attack: 10.0, release: 100.0, ratio: 1.0, threshold: 0.0)
  @sample_rate = srate
  @envelope = AttRelEnvelope.new(srate, attack: attack, release: release)
  @env_db = DC_OFFSET
  @ratio = ratio
  @threshold = threshold
end

Instance Attribute Details

#ratio=(value) ⇒ Object (writeonly)

:nodoc:



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# File 'lib/synth_blocks/fx/compressor.rb', line 57

def ratio=(value)
  @ratio = value
end

#threshold=(value) ⇒ Object (writeonly)

:nodoc:



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# File 'lib/synth_blocks/fx/compressor.rb', line 57

def threshold=(value)
  @threshold = value
end

#window=(value) ⇒ Object (writeonly)

:nodoc:



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# File 'lib/synth_blocks/fx/compressor.rb', line 57

def window=(value)
  @window = value
end

Instance Method Details

#attack=(attack) ⇒ Object

set attack



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# File 'lib/synth_blocks/fx/compressor.rb', line 78

def attack=(attack)
  @envelope.attack = attack
end

#release=(release) ⇒ Object

set release



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# File 'lib/synth_blocks/fx/compressor.rb', line 84

def release=(release)
  @envelope.release = release
end

#run(input) ⇒ Object

run compressor



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# File 'lib/synth_blocks/fx/compressor.rb', line 91

def run(input)
  rect = input.abs
  rect += DC_OFFSET
  key_db = lin2db(rect)

  over_db = key_db - @threshold
  over_db = 0.0 if over_db < 0.0

  # attack/release
  over_db += DC_OFFSET
  @env_db = @envelope.run(over_db, @env_db)
  over_db = @env_db - DC_OFFSET

  gr = over_db * @ratio - 1.0
  gr = db2lin(gr)
  input * gr
end