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

Returns a new instance of MidiFileWriter.



93
94
95
 
# 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 



106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
 
# 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 



97
98
99
100
101
102
103
104
 
# 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