class AudioStream::Fx::PeakingFilter
Public Class Methods
create(soundinfo, freq:, bandwidth: 1.0, gain: 40.0)
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@param soundinfo [AudioStream::SoundInfo] @param freq [Float] Cutoff frequency @param bandwidth [Float] bandwidth (octave) @param gain [AudioStream::Decibel] Amplification level at cutoff frequency
# File lib/audio_stream/fx/peaking_filter.rb, line 31 def self.create(soundinfo, freq:, bandwidth: 1.0, gain: 40.0) filter = new(soundinfo) filter.update_coef(freq: freq, bandwidth: bandwidth, gain: gain) filter end
Public Instance Methods
update_coef(freq:, bandwidth:, gain:)
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# File lib/audio_stream/fx/peaking_filter.rb, line 5 def update_coef(freq:, bandwidth:, gain:) if Decibel===gain gain = gain.db end omega = 2.0 * Math::PI * freq / @samplerate alpha = Math.sin(omega) * Math.sinh(Math.log(2.0) / 2.0 * bandwidth * omega / Math.sin(omega)) a = 10.0 ** (gain / 40.0) a0 = 1.0 + alpha / a a1 = -2.0 * Math.cos(omega) a2 = 1.0 - alpha / a b0 = 1.0 + alpha * a b1 = -2.0 * Math.cos(omega) b2 = 1.0 - alpha * a @coef = Vdsp::Biquad::Coefficient.new(b0/a0, b1/a0, b2/a0, a1/a0, a2/a0) @biquads.each {|biquad| biquad.coefficients = @coef } end