Class: Aubio::Beats

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

Instance Method Summary collapse

Constructor Details

#initialize(aubio_source, params) ⇒ Beats

Returns a new instance of Beats.



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# File 'lib/aubio/beats.rb', line 5

def initialize(aubio_source, params)
  # TODO: cleanup param dups
  @sample_rate = params[:sample_rate] || 44_100
  @window_size = params[:window_size] || 1024
  @hop_size    = params[:hop_size]    || 512

  @source = aubio_source
  @tempo = Api.new_aubio_tempo('specdiff', @window_size, @hop_size, @sample_rate)

  # create output for source
  @sample_buffer = Api.new_fvec(@hop_size)
  # create output for beat
  @out_fvec = Api.new_fvec(1)
end

Instance Method Details

#each ⇒ Object 



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# File 'lib/aubio/beats.rb', line 20

def each
  return enum_for(:each) unless block_given?

  total_frames_counter = 0
  read_buffer = FFI::MemoryPointer.new(:int)
  total_samples = Api.aubio_source_get_duration(@source).to_f

  loop do
    # Perform tempo calculation
    Api.aubio_source_do(@source, @sample_buffer, read_buffer)
    Api.aubio_tempo_do(@tempo, @sample_buffer, @out_fvec)

    # Retrieve result
    is_beat = Api.fvec_get_sample(@out_fvec, 0)
    no_of_bytes_read = read_buffer.read_int
    total_frames_counter += no_of_bytes_read

    if is_beat > 0.0
      tempo_samples = Api.aubio_tempo_get_last(@tempo)
      tempo_seconds = Api.aubio_tempo_get_last_s(@tempo)
      tempo_milliseconds = Api.aubio_tempo_get_last_ms(@tempo)
      tempo_confidence = Api.aubio_tempo_get_confidence(@tempo)

      output = {
        confidence: tempo_confidence,
        s: tempo_seconds,
        ms: tempo_milliseconds,
        sample_no: tempo_samples,
        total_samples: total_samples,
        rel_start: tempo_samples / total_samples
      }
      yield output
    end

    next unless no_of_bytes_read != @hop_size

    # there's no more audio to look at

    # Let's output one last tempo to mark the end of the file
    total_time = total_frames_counter.to_f / @sample_rate.to_f
    output = {
      confidence: 1.0,
      s: total_time,
      ms: total_time / 1000.0,
      sample_no: total_samples,
      total_samples: total_samples
    }
    yield output

    # clean up
    Api.del_aubio_tempo(@tempo)
    Api.del_fvec(@sample_buffer)
    Api.del_fvec(@out_fvec)

    break
  end
end