Class: WaveToJson

Inherits:
Object
  • Object
show all
Defined in:
lib/wave_to_json.rb,
lib/wave_to_json/cli.rb,
lib/wave_to_json/audio.rb,
lib/wave_to_json/version.rb,
lib/wave_to_json/shell_command.rb

Defined Under Namespace

Classes: Audio, CLI, ShellCommand

Constant Summary collapse

DEFAULT_PIXEL_PER_SECOND = 
1000 / 30.0
VERSION = 
"0.1.0"

Instance Method Summary collapse

Constructor Details

#initialize(source, destination, options = {}) ⇒ WaveToJson

Returns a new instance of WaveToJson.



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# File 'lib/wave_to_json.rb', line 9

def initialize(source, destination, options = {})
  @filename = source
  @output_path = destination
  @pixel_per_second = options.fetch(:pixel_per_second, DEFAULT_PIXEL_PER_SECOND)
  @channel = options.fetch(:channel, :both)
  @audio = Audio.new(@filename)
end

Instance Method Details

#calculate_ratios(mins, maxs) ⇒ Object 



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# File 'lib/wave_to_json.rb', line 55

def calculate_ratios(mins, maxs)
  max = 0
  results = (0..mins.length-1).map do |i|
    height = maxs[i] - mins[i]
    max = height > max ? height : max
    height
  end

  results.map { |result| (result / max.to_f).round(6) }
end

#generate ⇒ Object 



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# File 'lib/wave_to_json.rb', line 66

def generate
  File.open(@output_path, 'w') do |file|
    values = raw_values
    converted_values = calculate_ratios(*values)
    file.write(Oj.dump(converted_values))
  end
end

#raw_values ⇒ Object 



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# File 'lib/wave_to_json.rb', line 17

def raw_values
  min_values = []
  max_values = []

  contents = @audio.raw_data(channel: @channel)
  segment_size = (contents.length.to_f / width).to_i
  current_index = 0
  min = Audio::MAX_VALUE
  max = Audio::MIN_VALUE

  contents.each do |value|
    if current_index == segment_size
      max_values.push(max)
      min_values.push(min)

      current_index = 0
      min = Audio::MAX_VALUE
      max = Audio::MIN_VALUE
    else
      min = value < min ? value : min
      max = value > max ? value : max
      current_index+=1
    end
  end

  if current_index != 0
    max_values.push(max)
    min_values.push(min)
  end

  [min_values, max_values]
end

#width ⇒ Object 



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# File 'lib/wave_to_json.rb', line 50

def width
  duration_in_millisecond = @audio.duration * 1000
  @width ||= ( duration_in_millisecond/ @pixel_per_second).round
end