Class: StepSequencer::SoundPlayer

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(sources) ⇒ SoundPlayer

Returns a new instance of SoundPlayer.



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# File 'lib/step_sequencer/sound_player.rb', line 7

def initialize(sources)
  @sources = sources
  reset_state
end

Instance Attribute Details

#playing ⇒ Object (readonly)

Returns the value of attribute playing.



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# File 'lib/step_sequencer/sound_player.rb', line 5

def playing
  @playing
end

Instance Method Details

#build_matrix_from_string(string) ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 47

def build_matrix_from_string(string)
  string.tr(" ", '').gsub(/\#.+$/, '').split("\n").map(&:chars).map do |chars|
    chars.map do |char|
      if char == @hit_char then 1
      elsif char == @rest_char then nil
      else
        raise( StandardError,
          "
            Error playing from string. Found char #{char} which is not
            one of '#{@hit_char}' or '#{@rest_char}'.
          "
        )
      end
    end
  end
end

#calculate_rest_time(tempo) ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 107

def calculate_rest_time(tempo)
  # Tempo is seen as quarter notes, i.e. at 120 BPM there's 0.5 seconds
  # between steps
  60.0 / tempo.to_f
end

#init_matrix_state(matrix) ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 113

def init_matrix_state(matrix)
  @row_lengths = matrix.map(&:length)
  @active_steps = Array.new((matrix.length), 0)
end

#play(tempo: 120, string: nil, matrix: nil, limit: nil, hit_char: 'x', rest_char: '_') ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 12

def play(tempo: 120, string: nil, matrix: nil, limit: nil, hit_char: 'x', rest_char: '_')
  @limit = limit
  @hit_char, @rest_char = hit_char, rest_char
  if @playing
    raise( StandardError,
      "A sound player received #play when it was not in a stopped state.
       Use multiple instances instead"
    )
  end
  if matrix
    play_from_matrix(tempo: tempo, matrix: matrix)
  else
    play_from_string(tempo: tempo, string: string)
  end
  @playing = true
end

#play_from_matrix(tempo:, matrix:) ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 73

def play_from_matrix(tempo:, matrix:)
  init_matrix_state matrix
  rest_time = calculate_rest_time(tempo)
  @thread = Thread.new do
    loop do
      if @limit && (@steps_played >= @limit)
        stop # Thread kills itself, no need to break from the loop
      end
      matrix.each_with_index do |row, row_idx|
        play_next_step_in_row row, row_idx
      end
      @steps_played += 1
      sleep rest_time
    end
  end
end

#play_from_string(tempo:, string:) ⇒ Object

Raises:

  • (StandardError) 


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# File 'lib/step_sequencer/sound_player.rb', line 64

def play_from_string(tempo:, string:)
  raise(
    StandardError,
    "one of :string or :matrix must be provided for SoundPlayer#play"
  ) if !string
  matrix = build_matrix_from_string(string)
  play_from_matrix tempo: tempo, matrix: matrix
end

#play_next_step_in_row(row, row_idx) ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 90

def play_next_step_in_row row, row_idx
  Thread.new do
    row_length = @row_lengths[row_idx]
    active_step = @active_steps[row_idx]
    Thread.stop unless active_step
    step_content = row[active_step]
    if step_content
      path = @sources[row_idx]
      Thread.new { `mpg123 #{path} 2> /dev/null` }
    end
    @active_steps[row_idx] += 1
    if @active_steps[row_idx] >= row_length
      @active_steps[row_idx] = 0
    end
  end
end

#reset_state ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 34

def reset_state
  @thread = nil
  @playing = false # It can't be called multiple times at once.
                   # Use multiple instances instead.
                   # There's a check to precaution against this.
  @row_lengths = []
  @active_steps = []
  @steps_played = 0
  @limit = nil # an upper limit for steps_played, defaults to no limit
end

#stop ⇒ Object 



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# File 'lib/step_sequencer/sound_player.rb', line 29

def stop
  reset_state
  @thread&.kill
end