class MusicTheory::Note

Attributes

distort[RW]
duration[RW]
frequency[RW]
output_file_name[RW]

Public Class Methods

new(options = {}) click to toggle source
# File lib/music_theory/note.rb, line 8
def initialize(options = {})
  @frequency        = options[:frequency] || 440.0          # Note frequency in Hz
  @frequency        = @frequency.to_f
  @duration         = options[:duration] ||  1.0            # Number of seconds per note
  @distort          = options[:distort] || false
  @output_file_name = options[:output_file_name] || 'note'  # File name to write (without extension)
end

Public Instance Methods

cycles_per_frame() click to toggle source
# File lib/music_theory/note.rb, line 21
def cycles_per_frame
  # each frame, we want this fraction of a cycle:
  frequency / sample_rate
end
distort!(samples) click to toggle source
# File lib/music_theory/note.rb, line 43
def distort!(samples)
  samples.map do |sample|
    negative = sample < 0
    sample *= 8.to_f
    if sample.abs > 5
      sample = 5
      sample *= -1 if negative
    end
    sample /= 8.to_f
  end
end
samples() click to toggle source
# File lib/music_theory/note.rb, line 31
def samples
  # So to create a note that's one second long, we need to write out all the samples in the sine waves
  phase = 0
  samples = total_frames.times.map do
    sample = (Math.sin phase).to_f
    phase += sine_wave_cycle
    sample
  end
  samples = distort!(samples) if distort
  samples
end
sine_wave_cycle() click to toggle source
# File lib/music_theory/note.rb, line 26
def sine_wave_cycle
  # A cycle is a full sine wave, which is 2π radians:
  2 * Math::PI * cycles_per_frame
end
total_frames() click to toggle source
# File lib/music_theory/note.rb, line 16
def total_frames
  # We want 1 second of the note, so we need 1 second's worth of frames
  (duration * sample_rate).to_i
end