Class: Webmidi::SMF::Track

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/webmidi/smf/track.rb

Defined Under Namespace

Classes: NoteSpan

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name: nil, channel: nil) ⇒ Track

Returns a new instance of Track.



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# File 'lib/webmidi/smf/track.rb', line 12

def initialize(name: nil, channel: nil)
  @name = name
  @channel = channel
  @events = []
end

Instance Attribute Details

#channel ⇒ Object

Returns the value of attribute channel.



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# File 'lib/webmidi/smf/track.rb', line 10

def channel
  @channel
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/webmidi/smf/track.rb', line 10

def name
  @name
end

Instance Method Details

#<<(event) ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 27

def <<(event)
  add_event(event)
end

#add_event(event) ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 22

def add_event(event)
  @events << event
  self
end

#control_changes ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 76

def control_changes
  @events.lazy.select { |e| e.is_a?(MIDIEvent) && e.message.is_a?(Message::Channel::ControlChange) }
end

#each(&block) ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 31

def each(&block)
  @events.each(&block)
end

#events ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 18

def events
  @events.dup
end

#note_spans ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 43

def note_spans
  active = Hash.new { |hash, key| hash[key] = [] }
  spans = []
  use_delta_time = @events.all? { |event| event.absolute_time.zero? }
  tick = 0

  @events.each do |event|
    tick += event.delta_time
    next unless event.is_a?(MIDIEvent) && note_event?(event.message)

    time = use_delta_time ? tick : event.absolute_time
    message = event.message
    key = [message.channel, message.note]

    if message.is_a?(Message::Channel::NoteOn) && message.velocity.positive?
      active[key] << [event, time]
    elsif (started = active[key].shift)
      start_event, start_time = started
      spans << NoteSpan.new(
        note: message.note,
        channel: message.channel,
        start_time: start_time,
        end_time: time,
        duration: time - start_time,
        note_on: start_event,
        note_off: event
      )
    end
  end

  spans
end

#notes ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 39

def notes
  @events.lazy.select { |e| e.is_a?(MIDIEvent) && note_event?(e.message) }
end

#quantize!(grid) ⇒ Object

Raises:



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# File 'lib/webmidi/smf/track.rb', line 114

def quantize!(grid)
  raise InvalidSMFError, "Quantize grid must be a positive integer, got #{grid.inspect}" unless grid.is_a?(Integer) && grid.positive?

  @events.each do |event|
    event.absolute_time = ((event.absolute_time.to_f / grid).round * grid).to_i
  end
  recalculate_delta_times!
end

#recalculate_delta_times! ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 104

def recalculate_delta_times!
  sort_by_absolute_time!
  previous = 0
  @events.each do |event|
    event.delta_time = event.absolute_time - previous
    previous = event.absolute_time
  end
  self
end

#size ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 35

def size
  @events.size
end

#sort_by_absolute_time! ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 99

def sort_by_absolute_time!
  @events.sort_by!(&:absolute_time)
  self
end

#tempo_changes ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 80

def tempo_changes
  @events.lazy.select { |e| e.is_a?(MetaEvent) && e.type == MetaEvent::META_TYPES[:tempo] }
end

#transpose(semitones) ⇒ Object 



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# File 'lib/webmidi/smf/track.rb', line 84

def transpose(semitones)
  new_track = Track.new(name: @name, channel: @channel)
  @events.each do |event|
    if event.is_a?(MIDIEvent) && note_event?(event.message)
      msg = event.message
      new_note = (msg.note + semitones).clamp(0, 127)
      new_msg = msg.with(note: new_note)
      new_track << MIDIEvent.new(message: new_msg, delta_time: event.delta_time, absolute_time: event.absolute_time)
    else
      new_track << event
    end
  end
  new_track
end