Midi_recorder - record and print midi notes played

Creations & Ideas
1

Hi,

I just started using Sonic Pi this week. It looks really interesting. One thing I wasn’t sure about was how to code a tune when you don’t know the note names or numbers. Sometimes it’s easier to pick out a tune on a keyboard. So I wrote this script midi_recorder.rb which records what you play, then 5 beats after you stop playing it prints out all the notes you played in start order. For each note it gives the note number, the midi velocity, the start time and duration held. It’s formatted as a ruby list of lists. I hope it might be useful.

Murray

# midi_recorder - records midi notes, then prints what was played
# Start the script, play your midi device, then 5 beats after
# you finish the note sequence will be printed as a list.
# Each list item is [note, velocity, start time, duration].

use_debug false
current_down = []
last_up = []
sequence = []
kbd = "/midi*/note_on"
resolution = 0.125
b = 0
last_event_time = 0
seq_start = -1

define :note_start do |note, amp|
  t = b - seq_start
  note_record = [note, amp, t]
  current_down += [note_record]
end

define :note_end do |note|
  t = b - seq_start
  ended = []
  current_down.each do |down|
    if down[0].equal?(note)
      ended += [down]
    end
  end
  ended.each do |up|
    info = up + [t-up[2]]
    last_up += [info]
  end
  current_down = current_down - ended
end

define :show_played do
  if !last_up.empty? and last_event_time+resolution < b
    sequence += last_up
    last_up = []
  end
  if !sequence.empty? and last_event_time+5 < b
    sequence.sort! { |a,b| a[2] <=> b[2] }
    print sequence
    sequence = []
    seq_start = -1
  end
end

live_loop :recorder do
  use_real_time
  note, amp = sync kbd
  last_event_time = b
  if seq_start==-1
    seq_start = b
  end
  if amp==0
    note_end(note)
  else
    note_start(note, amp)
  end
  
  play note, amp: amp/127.0
end

live_loop :metronome do
  use_real_time
  if factor?(b,1)
    sample :perc_snap, amp: 0.4
  end
  sleep resolution
  b = b + resolution
  show_played
end
2 Likes
2

Thanks for sharing. I am also noob here. I am considering using your code to get what was played from a random choice and then harmonize. I wonder if there is already a simpler way.

3

There will be a simpler way. The Sonic Pi tutorials give lots of ideas about what can be done, including section 4. Randomisation and 8.2 Chords which could be useful. Maybe take the MIDI In loop from the tutorials, and as well as playing the note, construct a chord from the note and also play one or more other notes from the chord.