Class: Sidtool::MidiFileWriter

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

Defined Under Namespace

Classes: DeltaTime, EndOfTrack, KeySignature, NoteOff, NoteOn, ProgramChange, TimeSignature, TrackName

Instance Method Summary collapse

Constructor Details

#initialize(synths_for_voices) ⇒ MidiFileWriter 



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# File 'lib/sidtool/midi_file_writer.rb', line 93

def initialize(synths_for_voices)
  @synths_for_voices = synths_for_voices
end

Instance Method Details

#build_track(synths) ⇒ Object 



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# File 'lib/sidtool/midi_file_writer.rb', line 106

def build_track(synths)
  waveforms = [:tri, :saw, :pulse, :noise]

  track = []
  current_frame = 0
  synths.each do |synth|
    channel = waveforms.index(synth.waveform) || raise("Unknown waveform #{synth.waveform}")
    track << DeltaTime[synth.start_frame - current_frame]
    track << NoteOn[channel, synth.tone]
    current_frame = synth.start_frame

    current_tone = synth.tone
    synth.controls.each do |start_frame, tone|
      track << DeltaTime[start_frame - current_frame]
      track << NoteOff[channel, current_tone]
      track << DeltaTime[0]
      track << NoteOn[channel, tone]
      current_tone = tone
      current_frame = start_frame
    end

    end_frame = [current_frame, synth.start_frame + (FRAMES_PER_SECOND * (synth.attack + synth.decay + synth.sustain_length)).to_i].max
    track << DeltaTime[end_frame - current_frame]
    track << NoteOff[channel, current_tone]

    current_frame = end_frame
  end

  track
end

#write_to(path) ⇒ Object 



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# File 'lib/sidtool/midi_file_writer.rb', line 97

def write_to(path)
  tracks = @synths_for_voices.map { |synths| build_track(synths) }

  File.open(path, 'wb') do |file|
    write_header(file)
    tracks.each_with_index { |track, index| write_track(file, track, "Voice #{index + 1}") }
  end
end