Elixir, MIDI and LiveView

(Paris.Ex meetup)

Transcript

1. Elixir, MIDI
   & LiveView
   

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2. @thibaut_barrere
   Consultant
   Ruby / Elixir / Ansible
   Kiba ETL / Kiba Pro
   Remote 100% (Charente Maritime)
   

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3. Elixir =>
   Code-Centric Digital
   Audio Workstation?
   infiniwip (tm)
   

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4. Previous episode
   https://github.com/thbar/demo-elixir-reloading-music
   Code.eval_file("music.exs")
   

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5. MIDI
   

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6. Note On
   {0x90 + channel, note, velocity}
   Note Off
   {0x80 + channel, note, release_velocity}
   

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7. Keyboard / Piano / Synthetizers
   photo by Clavia
   

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8. MIDI controllers
   photo by Novation
   

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9. Virtual Instruments (on computer)
   

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10. Virtual Instruments (on iOS)
    photo by Korg
    

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11. Lightning = Inter-Device Audio & MIDI (IDAM)
    photo by Apple
    

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12. Elixir
    Code / DRY
    Refactoring Music
    Augmented Human (theory, scales)
    Soft realtime
    

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13. brew install portmidi
    

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15. # Start a process for MIDI event queue
    {:ok, pid} = PortMidi.open(:output, "Kontakt Virtual Input")
    note = 48 # C-4
    velocity = 127
    # Send "NOTE ON"
    PortMidi.write(pid, {0x90, note, velocity})
    # Send "NOTE OFF"
    PortMidi.write(pid, {0x80, note})
    

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17. Computer: Note 60
    Human: WTF????
    

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18. Translation
    def note_number_to_latin_name(midi_note, middle_c \\ @default_middle_c) do
    remap_note(midi_note, @latin_names, middle_c)
    end
    defp remap_note(midi_note, names, middle_c) do
    offset = get_base_offset(middle_c)
    octave = div(midi_note + offset, 12)
    octave_note = rem(midi_note + offset, 12)
    octave_note = names |> Enum.at(octave_note)
    "#{octave_note}#{octave}"
    end
    defp get_base_offset("C4"), do: -12
    

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19. DocTests ❤
    ## Examples
    iex> MusicRef.note_number_to_latin_name(60)
    "Do4"
    iex> MusicRef.note_number_to_latin_name(78)
    "Fa#5"
    

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20. Phoenix LiveView
    
    
    Time is
    
    
    HTML? ✔
    

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21. Phoenix LiveView
    
    
    
    
    
    SVG? ✔
    

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22. Phoenix LiveView
    
    
    # white notes
    
    
    # black notes
    
    
    

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25. def note_on({channel, note, velocity}, device, portmidi \\ PortMidi) do
    Phoenix.PubSub.broadcast(Widgets.PubSub, "notes", {:note_on, note})
    :ok = portmidi.write(device, {0x90 + channel, note, velocity})
    end
    

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27. Code & Demo
    

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