Class: AudioStream::Fx::LowPassFilter

Inherits:
BiquadFilter show all
Defined in:
lib/audio_stream/fx/low_pass_filter.rb

Constant Summary

Constants inherited from BiquadFilter

BiquadFilter::DEFAULT_Q

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from BiquadFilter

#initialize, #plot, #plot_data, #process

Constructor Details

This class inherits a constructor from AudioStream::Fx::BiquadFilter

Class Method Details

.create(soundinfo, freq:, q: DEFAULT_Q) ⇒ Object

Parameters:



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# File 'lib/audio_stream/fx/low_pass_filter.rb', line 27

def self.create(soundinfo, freq:, q: DEFAULT_Q)
  filter = new(soundinfo)
  filter.update_coef(freq: freq, q: q)

  filter
end

Instance Method Details

#update_coef(freq:, q:) ⇒ Object 



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# File 'lib/audio_stream/fx/low_pass_filter.rb', line 5

def update_coef(freq:, q:)
  freq = Rate.freq(freq)

  omega = freq.sample_phase(@soundinfo)
  alpha = Math.sin(omega) / (2.0 * q)

  a0 = 1.0 + alpha
  a1 = -2.0 * Math.cos(omega)
  a2 = 1.0 - alpha
  b0 = (1.0 - Math.cos(omega)) / 2.0 
  b1 = 1.0 - Math.cos(omega)
  b2 = (1.0 - Math.cos(omega)) / 2.0 

  @coef = Vdsp::Biquad::Coefficient.new(b0/a0, b1/a0, b2/a0, a1/a0, a2/a0)
  @biquads.each {|biquad|
    biquad.coefficients = @coef
  }
end