Class: Aubio::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/aubio.rb

Instance Method Summary collapse

Constructor Details

#initialize(path, params) ⇒ Base

Returns a new instance of Base.

Raises:



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# File 'lib/aubio.rb', line 16

def initialize(path, params)
  raise FileNotFound unless File.file?(path)

  sample_rate = params[:sample_rate] || 44_100
  hop_size    = params[:hop_size]    || 512

  @is_closed = false
  @source = Api.new_aubio_source(path, sample_rate, hop_size)
  @params = params

  check_for_valid_audio_source(path)
end

Instance Method Details

#beats ⇒ Object 



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# File 'lib/aubio.rb', line 52

def beats
  check_for_closed

  beats = Beats.new(@source, @params).each.to_a

  # fill in the zero beat
  beats = beats.unshift(
    beats.first.merge({
                        confidence: 1,
                        s: 0.0,
                        ms: 0.0,
                        sample_no: 0,
                        rel_start: 0.0
                      })
  )

  # fetch the rel_end from the next beat
  # using 1.0 for the last beat
  beats = beats.each_cons(2).map do |a, b|
    a.merge({
              rel_end: (b[:rel_start] || 1.0)
            })
  end

  # set minimum inter-onset interval in seconds
  # allows for 4/4 at 400bpm (faster than most music)
  # filters beats detected too closely together
  minioi = @params[:minioi] || 0.15
  filtered_beats = [beats.first]
  beats.each do |b|
    filtered_beats << b if (b[:s] - filtered_beats.last[:s]) > minioi
  end

  # TODO: are there other smoothing methods that would be useful here?
  filtered_beats
end

#bpm ⇒ Object 



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# File 'lib/aubio.rb', line 89

def bpm
  check_for_closed

  beat_locations = beats
  beat_periods = beat_locations.each_cons(2).map { |a, b| b[:s] - a[:s] }

  return 60.0 if beat_locations.length == 1

  # use interquartile median to discourage outliers
  s = beat_periods.length
  qrt_lower_idx = (s / 4.0).floor
  qrt_upper_idx = qrt_lower_idx * 3
  interquartile_beat_periods = beat_periods[qrt_lower_idx..qrt_upper_idx]

  # Calculate median
  iqs = interquartile_beat_periods.length

  iq_median_beat_period = interquartile_beat_periods.sort[(iqs / 2.0).floor - 1]
  60.0 / iq_median_beat_period
end

#close ⇒ Object 



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# File 'lib/aubio.rb', line 29

def close
  Api.del_aubio_source(@source)
  @is_closed = true
end

#enum_beats ⇒ Object 



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# File 'lib/aubio.rb', line 46

def enum_beats
  check_for_closed

  Beats.new(@source, @params).each
end

#onsets ⇒ Object 



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# File 'lib/aubio.rb', line 34

def onsets
  check_for_closed

  Onsets.new(@source, @params).each
end

#pitches ⇒ Object 



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# File 'lib/aubio.rb', line 40

def pitches
  check_for_closed

  Pitches.new(@source, @params).each
end